EEL 4914 - Final Paper by panniuniu

VIEWS: 65 PAGES: 131

									        Group #1


   Senior Design Paper



Smart-Green House


       Group Members:
         Kaltrin Gjini
      Richie Ramsahoye
        Rafael Abreu
       Danny Gonzales
                                              TABLE OF CONTENTS

Section 1 – EXECUTIVE SUMMARY ................................................................................. 1
Section 2 – DESIGN & RESEARCH RELATED TO GROWING SYSTEM ........................ 2
Subsection 2.1 – Methods related to growing plants ................................................................3
    Subsection 2.1.a – Comparisons of different plant growing methods ............................................ 3
    Subsection 2.1.b – Design decisions and parameters of growing system .................................... 13
Subsection 2.2 – Design and Research related to Light Source Implementation ..............14
    Subsection 2.2.a – Comparisons of different light source implementations ................................. 14
    Subsection 2.2.b – Circuit Design for Light Source .................................................................... 18
Subsection 2.3 – Research and Design Related to Nutrient Detection & Distribution .......26
    Subsection 2.3.a – Nutrient Detection Research and Design ..................................................... 26
    Subsection 2.3.b – Nutrients Distribution Research and Design ................................................. 28
Subsection 2.4 – Water Management Design..........................................................................30
Subsection 2.5 – Test Procedures for the Growing System ..................................................32
Subsection 2.4 – Conclusions reached in Designing the Growing System .........................34
Section 3 – DESIGN & RESEARCH RELATED TO SMART HOUSE CONTROLS ........ 35
Subsection 3.1 – Smart House Definitions and Ideology .......................................................35
Subsection 3.2 – Similar Technologies .....................................................................................36
    Subsection 3.3.a – Smart Power Strip ...................................................................................... 36
    Subsection 3.3.b – Timers........................................................................................................ 37
Subsection 3.3 – Smart House Security ..................................................................................38
    Subsection 3.3.a – Similar Smart House Security ...................................................................... 38
    Subsection 3.3.b – Smart House Health Devices....................................................................... 39
Subsection 3.4 – Design Features being incorporated in the Smart House Project .........40
Subsection 3.5 – Voice and Communication Research & Design .......................................41
    Subsection 3.5.a – X10 ............................................................................................................ 41
    Subsection 3.5.b – Universal Powerline Bus ............................................................................. 41
    Subsection 3.5.c – ONE-NET ................................................................................................... 42
    Subsection 3.5.d – Z-wave ....................................................................................................... 42
    Subsection 3.5.e – DASH7....................................................................................................... 43
Subsection 3.6 – Microcontroller ...............................................................................................44
    Subsection 3.6.a – Selection of Microcontroller ......................................................................... 44
    Subsection 3.6.b – Arduino Duemilanove ATMega 168 Microcontroller ...................................... 45
    Subsection 3.6.c – MSP430 Launchpad Value Line Development Kit ......................................... 45
    Subsection 3.6.d – rfPIC with Transmitter ................................................................................. 46
    Subsection 3.6.e – MSP430AFE42xx Microcontroller ................................................................ 47
    Subsection 3.6.f – CC430 RF Microcontroller ............................................................................ 48
Subsection 3.7 – Specifications for the Wall Unit ...................................................................49
    Subsection 3.7.a – Power Supply Design .................................................................................. 51
    Subsection 3.7.b – Load Control Parameters, Research, and Design ......................................... 52
    Subsection 3.7.c – Sensors Specifications and Control Parameters ........................................... 58
    Subsection 3.7.d – RF Communication ..................................................................................... 59
Subsection 3.8 – Testing Conditions and Procedures for the Wall unit ..............................60
Subsection 3.9 – Conclusions on Wall Unit Design ...............................................................63
Section 4 –DESIGN & RESEARCH RELATED TO CENTRAL CONTROL UNIT ............ 64
Subsection 4.1 – Hardware Research & Design For Central Control Unit ..........................64
    Subsection 4.1.a – Introduction ................................................................................................ 64
    Subsection 4.1.b – Button Interface .......................................................................................... 69
    Subsection 4.1.a – USB Translator ........................................................................................... 71
Subsection 4.2 – Central Control Core Specifications ............................................................73
    Subsection 4.2.a – Central Control Core ................................................................................... 73
       Subsection 4.2.b – Display properties and design ..................................................................... 75
       Subsection 4.2.c – Power Interfaces and conversions ............................................................... 79
       Subsection 4.2.d – Environment of Operation ........................................................................... 80
       Subsection 4.2.e – Similar Technologies ................................................................................... 84
       Subsection 4.2.f – Testing and Troubleshooting ........................................................................ 89
       Subsection 4.2.g – Conclusions on Central Control Unit Design ................................................. 93

Section 5 – COMMUNCATIONS DESIGN AND RESEARCH .......................................... 95
Subsection 5.1 – W IRELESS VS. W IRED COMMUNICATION .........................................................95
    Subsection 5.1.a – Wired ......................................................................................................... 95
    Subsection 5.1.b – Wireless ..................................................................................................... 96
Subsection 5.2 – Different Approaches to Wireless Interface .............................................100
    Subsection 5.2.a – Wi-Fi 802.11 ............................................................................................. 100
    Subsection 5.2.b – Zigbee...................................................................................................... 100
Subsection 5.3 – Cellular Phone Connection to Smart Green House ................................102
    Subsection 5.3.a – iPhone ..................................................................................................... 102
    Subsection 5.3.b – Android .................................................................................................... 102
Subsection 5.4 – Comparisons of Technologies ..................................................................103
Section 6 – SYSTEM SECURITY ................................................................................... 105
Subsection 6.1 – SECURITY ISSUES FOR LANS ........................................................................105
Subsection 6.2 – Security Issues for WANs ...........................................................................106
Subsection 6.3 – Encryption .....................................................................................................106
Section 7 – PROJECT MANAGEMENT RESEARCH AND DESIGN ............................. 106
Subsection 7.1 – CLASS DIAGRAMS ..........................................................................................108
Subsection 7.2 – Use Case Diagrams ....................................................................................110
Subsection 7.3 – Software Design ...........................................................................................113
Subsection 7.4 – Simulation and Implementation .................................................................113
    Subsection 7.4.a – Packages ................................................................................................. 113
    Subsection 7.4.b – Mediator Pattern Implementation ............................................................... 114
    Subsection 7.4.c – Sensors .................................................................................................... 115
    Subsection 7.4.b – Technical Specifications ............................................................................ 116

Section 8 – SYSTEM WALK-THROUGH........................................................................ 117
Section 9 – ADMINISTRATIVE INFORMATION ............................................................ 120
Subsection 9.1 – Time Allocation .............................................................................................120
Subsection 9.2 – Budget and Financing .................................................................................121
Section 10 – APPENDIX ................................................................................................. 123
Subsection 10.1 – References .................................................................................................123
Subsection 10.2 – Illustration Permissions .............................................................................125
Section 1 – Executive Summary
This project is a smart greenhouse project, which utilizes the properties of a
greenhouse and a smart house. This project contains a growing system as well
as a smart house system, which can be controlled through a central control unit
or through wireless capabilities. The goals of this project are to maintain an
efficient growing system while having an inexpensive setup of the smart house
controlled with an efficient control unit or intuitive software based controls. The
main purpose of this project is to produce plants in an efficient manner with
independence to sunlight and fertile soil. The reason this project is being pursued
is the dire need of sustainable plants within harsh climates such as third world
countries. With this project, plants within this system can be grown indoors and
will have all the necessities it requires to progress through the cycle of life thus
allowing for the possibility of this system being implemented in harsh climates.

This project will introduce the concept of fully automated growing system where
plants present in the system will be nourished, fed, and maintained automatically
through designed control circuits. These control circuits have the properties of
having low power consumption as possible while keeping the materials used in
the system inexpensive as the budget can maintain. The central control unit of
the project will also have the properties of using low power while keeping the
expenses low to enable the system to be commercially viable and affordable.

This project will explore the territories of Radio Frequency technology to enable
wireless communication between components and enable the use of power
conversion to use utility power lines to power the components existing in the
project. The project will also use modular design for the central control unit to
increase the scalability while maintaining the properties of efficiency among the
system. Different techniques for growing solutions will be explored where an
aeroponics system will be implemented into the project for full automation,
increase in expandability, greater efficient use of resources, and use of
inexpensive materials. The project will use software to control and give
information on data on the specific parameters of the project such as power
consumption, temperature, and water level within the growing system. All of
these requirements will be met with the many designs that reside within the
project’s goals.

Overall, this project will yield an efficiently designed smart greenhouse which will
be automated as well as have low maintenance while keeping the expenses and
power consumption at low levels such that it will produce thriving plants in an
eco-friendly manner in hopes to reaffirm the protection of the environment all
while exploring new technologies and gaining new knowledge. This project will
serve as an example of how to implement plant systems, which are independent
on sunlight while remaining efficient in plant growth and being fully automated at
the same time.


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Section 2 – Design & Research Related to
Growing System
The growing system of this project serves the purpose of growing plants in a self-
maintainable fashion where the different systems will control the process of
feeding nutrients to the plants, supplying water to the plants, and the lights to
trigger photosynthesis such that the plants can have energy. Figure 1 shows the
block diagram of the overall system as well as the connections to the Central
Control Unit.




               Figure 2.1: Block Diagram of the Overall Growing System

As can be seen by the block diagram of the growing system, many systems
controls and fulfills the needs of the plants within the system. The growing
system will use a certain method to grow the plants successfully and in an
inefficient manner. The nutrients detection system will help detect nutrients in the
plants or system, will output to the nutrients distribution system, and will enable
the system if insufficient amounts of nutrients are present in the growing system.
The water level detection system will detect the amount of water is present in the
growing system and if more water is needed or not. If water is needed, the level
detection system will enable the water pumps that will distribute more water into
the system. The light source system will output light such that the process of
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photosynthesis will trigger and give energy to the plant. All of these systems will
be powered by a power supply, which can be independent in nature. Overall, the
growing system will be designed to be a fully functional system that will be
efficient in power consumption and inexpensive in design.

Subsection 2.1 – Methods Related to Growing
Plants
For this section of the project, the main objective is to find the best growing
solution for nurturing the plants. The growing solutions must be able to maintain
the conservation of resources in hopes to keep the cost and the usage of
resources at the best efficiency as possible. The reliability of the solution is
important as well because the quality and the sustainability for each plant are
vital for the success of this project. The project must also be able to deliver the
nutrients for the plants in the most efficient and cost effective way as possible
best delivery so that the cost of nutrients is limited and the usage of the nutrients
can be efficient. Another concern about this project is the efficiency of the
amount of plants that can be grown within a given time. This concerns the
amount of useable yield from each plant root. The amount of yield is the fullness
of the plant and the amount of the plant that can be used. These plants are
namely vegetables or fruits and the amount of yield is important for the success
of a normal greenhouse. The growing solution must also be able to be
expandable and easily maintainable such that the project can be on a larger
scale and does not need much maintenance if implemented. Overall, this section
will examine a number of growing solutions and choose the best approach for the
design of the project.

Subsection 2.1.a – Comparisons of different plant
growing methods
The first growing approach that will be analyzed is the conventional soil method
in which soil is used as the growing medium for nurturing the plant. With this
growing method, the plants are grown in the soil where nutrients are absorbed at
the roots through the soil. In this case, the soil must be viable for plant nutrients
to provide as a good medium. As such, fertilizer is used to provide nutrients to
the plants if the soil is deemed unsuitable or generic. Water is distributed into the
soil such that the roots of the plants are able to get the water from the soil.

Plants absorb the vital nutrients through the soil to survive. For the plant to
sustain life, the plant absorbs water through the soil such that more water must
be supplied through the soil for the plant to have more access to water. Without
enough attention to the soil and water distributions, over-watering and under-
watering might occur such that the plant has too much supplied water or too low
amount of supplied due to the lack of access to oxygen in both cases,
respectively.

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The solution is the most conventional and convenient method for plant growing
as it is simple and easy to implement into this project. The distribution of water
and nutrients for the plants is also easy to implement into the project, as the
design would be simplistic in nature. This method is also, to some extent, cost
effective as the cost of soil and fertilizer would be inexpensive with respect to the
resource of the project. This approach seems like the most natural way that a
plant is grown, through soil, water, and fertilizer. Although all of these advantages
stand out for the design of this growing system, several disadvantages go
against the project specifications.

The disadvantages in using soil as the medium for growing the plants are that the
use of resources becomes strained when compared to the throughput of the
plant. With the usage of resources to maintain the plant, it is clear to see that the
usage of water and nutrients to be used is not to efficiency as the roots absorbed
the nutrients through the soil. The amount of water is dissipated into the soil
leaving the possibility that the roots might actually never attain the necessary
water it needs to live. The efficiency of the absorption of water is vital to the
plant’s quality and sustainability. The amount of time that the water takes to be
absorbed by the roots is also critical therefore leaving the soil solution of the
growing method at a disadvantage because it will take time for the roots to
absorb the moisture from the soil. It can be observed as well that the amount of
water and nutrients needed to maintain the plant is way too much for each plant
because of the rate of absorption is lowered due to the soil such that there would
need to be more compensation on the amount of water to be used to keep the
plants living. This makes part of the soil growing solution implementation quite
costly because the cost of water used outweighs the cost of soil and fertilizer.
The cost of the fertilizer, although cheap, would increase because of this
because more fertilizer would need to be used for the implementation and
maintaining process.

What can also be observed through this solution is that the amount of yield in
growing the plants will be limited as well. With the lack of efficiency on the rate of
absorption due the soil medium and the amount of resources to be used in the
implementation to be strained to capacity, the amount of plants grown in a given
time will be limited and dependent on the amount of resources that can be
consumed. Maintenance of the system must also be considered for the
evaluation of this growing solution. Because of the hazards of over-watering or
under-watering of plants, special care must be in place such that this possibility
never occurs. Even if the plants were separated in individual pods and water
were to be distributed uniformly across the system, the possibility of over-
watering and under-watering still exists because the soil medium has an
unreliable and inconsistent rate of absorption for the plants. Because of the
inconsistency of the rate of absorption among the plants, special attention must
be put in place such that the plants get enough oxygen for sustainability. With
respect to the type of soil used, it is unknown of any living pests present in the
soil. Due to this fact, the sustainability and reliability of the plant can be affected

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as pests and diseases feed off the plants leaving the plants in a poor state.
Because of this, the transmission of diseases among the plants in a shared soil
medium becomes a key issue with this growing implementation.

There are further concerns about the plants health is an issue with this
implementation such as plant-to-plant transmission of diseases. This plant-to-
plant transmission of diseases is because the soil is shared between each plant.
If there is one plant that is afflicted by disease, the neighboring plants will also be
rendered unhealthy even though it is healthy. This is due to the disease being
transmittable through the soil as with the case with plant nutrients through
fertilizer. Because of this, the possibility that one whole batch of crops can be
effected by disease from just one diseased plant. This would affect the
sustainability of the project and will cause many concerns for each individual
plant if this implementation were used. One solution can be to separate each
plant bud into separate pots such that each plant would not share the soil so that
the diseases can be transmitted. Although this is a presentable solution for this
implementation, it raises more issues. The complexity of the implementation is
increased as the distribution of plant nutrients and water needs to be
implemented for every single plant. This would be ideal for a small-scale project
but with a project that is larger, it would be arduous to make a distributor for each
plant. This would be even more difficult if the project is aiming to be expandable,
as the amount of distributors would increase at the rate of the expansion of the
project. This is deemed too inefficient for the project because of the outlying cost
would increase and the amount of workload to expand increases. Maintenance
for each plant and distributor would be increased as well as extra attention is
needed for every distributor.

One can certainly argue that the distribution system can be implemented on a
wide scale such that one distributor can water a few plants at a time but the
previous problems are still present but are alleviated to some extent where it
lessens the load of maintenance and opens up some expandability.
Nevertheless, control of resources is not uniform therefore this approach affects
plant health and reliability if some plants are over or under nurtured. Since the
project is focused on efficiency between the distribution of water and nutrients
into the plants, the water flow and nutrients distribution must be controlled such
that only necessary amounts of these resources are used. Therefore, this
solution is not viable for the project with all these disadvantages.

With the soil growing implementation being disadvantageous towards the project
goals, another growing method will be analyzed, namely hydroponics.
Hydroponics is a method of growing that uses water as the medium for the
growth of the plant. Instead of using soil, this method uses water for the support
of roots. This method sounds unconventional because of the absence of soil and
fertilizer but the nutrients are distributed among the water such that the roots
absorb the nutrients through the water.



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There are many advantages in having the hydroponics system implemented as
the growing system in this project. The advantages of using the hydroponic
growing solution are the less use of resources, higher reliability of grown plants,
is easily implementable into the project, and enables control of some plant
diseases among the plants such that the plants can stay healthy. With these
advantages, this approach appears to be a viable solution for the growing
apparatus of the greenhouse system. Figure 2.2 shows an example of how a
hydroponics system is implemented where the components necessary for the
system to function is also shown.




                   Figure 2.2: An example of a hydroponics system
            (Reprinted with permission from hydroponiki.pbworks.com [1])

As seen in the figure, the plants are held in a support mechanism for the roots
stability and the water is concentrated with nutrient solution. The support
mechanisms are usually soil substitutions that are inert. As seen in the figure, an
air stone is used to pump oxygen into the solution such that there will be more
oxygen amongst the water even after the plants absorb said oxygen present in
the solution. The distribution of oxygen among the nutrient solution solves the
previous issues with the conventional soil method where over-watering and
under-watering might occur such that the plants will not have access to enough
oxygen.

A hydroponic system can use less water in the system by reusing water used in
the system. With the medium being water in the system, this already saves on
the watering of the plants. Because this system can use recycled water, this
reduces the cost of water making it cost effective in terms of water. Nutrients for
the plants are distributed within the medium of water giving the system the ability
to control the amount of nutrients are present in the water. With this control, the
nutrients cost can be distributed in such a method such that the system will be
cost effective. Because the nutrients can be distributed through the water, the
roots of the plants can easily obtain the proper nutrients it needs such that the
rate of absorption is increased when compared to the soil growing system.
Because water is used as the medium, the roots already get the necessary water
it needs for sustainability. It makes sense that this solution can yield high
efficiency when it comes to the usage of water for the plants.

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Therefore, the implementation for the hydroponics system is simple to apply in
the project with respect to the water distribution system, as the water would act
as a placeholder for the roots of the plants. The design of the nutrients
distribution for the hydroponics system is easily implementable for the project
design as the water used in the system can be concentrated with the necessary
nutrients for the plants. This can be implemented through a drip system, which
uses concentrated volumes of the nutrients distributed into fluid. This makes the
implementation of the nutrients distribution system simple as all is needed is a
sensor to detect nutrients level in water. The handling of contamination of plants
is also a major concern as well.

Even though the hydroponics growing method can control the prevention and
further infection of plant disease transmission, there are still some possible
fallouts due to the nature of the system. Because of the use of water as the
growing medium, the levels of moisture among the plants in the system are
particularly high. Certain plant diseases can be spread through the plants like
Verticillium Wilt, Phytium, Root Rot, or Damp Off. These moisture conditions can
cause major problems with the sustainability of the plants’ life. Moreover,
because there is minimal plant uniqueness due to the nature of the hydroponic
method being for selective with which plants can be grown hydroponically, the
chances for disease transmission through the water medium are increased.
Some plants cannot be grown hydroponically as the plants cannot withstand the
amount of saturation of water is present, or are too weak for implementation of
the system, or cannot withstand the natural conditions in a normal hydroponic
which are less than high temperatures and high moisture levels. Because of
these conditions, salmonella infestation is even a possibility, which is a very high-
risk scenario as salmonella detection among the crops would be expensive within
the scope of the project as the detection is usually done through filtering the
water and finding the production of hydrogen sulfide.

Another concern about this project is the expandability of the growing system
such that it can be implemented on a much larger scale with multiple productions
of plants. With this growing method, it does not seem like any possible variations
of this method would be easily expandable as there are major limitations with
respect to the types of plants that can be grown. Each different plant has different
nutrient needs where a tomato might need different nutrients from a potato for
example. Because of the way that the hydroponics system works, this would not
be possible with the system because the nutrient solution would need to be
limited to that specific plant. If more plants were to be grown, different
hydroponics systems would need to be implemented. Similar plants that require
the similar kinds of nutrients can indeed thrive successfully on the same
hydroponic system but different kinds of plants would affects the systems overall
sustainability. If the plant that required different nutrients were to be grown in the
same system with thriving plants, the possibility that the different plant would die
is very probable. Even more so, the plant might develop one of the common
diseases of the implementation of the hydroponics unit. This will affect all of the

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other plants in the system, as the possibility that the disease will spread to the
other roots is increasingly high.

Another factor that affects the expandability of this growing method is the size
constraints to implement such a process. Because of the size implementation of
the hydroponic system for one unit of plants, the rate of expandability is
diminished. Moreover, expansion of the project might not even be possible on a
wide scale due to size of facilities. If more than one type of plants were
implemented in a hydroponic system, it would require more hydroponic systems
if there exists some plants that require a different nutrient solution. Therefore, it
stands to reason that the size of the implementation of multiple hydroponic
systems would result in massive use of size constraints. Due to the size
constraints of the implementation of this growing method, the projects budget
becomes an issue as well. If more than one type of plants were to be grown, the
expense of using multiple hydroponics system would be detrimental to the rest of
the project’s budget. The materials used to support the hydroponics structure and
the elements used to hold the system together are manageable on a small scale.
However, once the project expands, the budget would be in jeopardy of creating
a deficit as oppose to any income. Over time, the project will yield some sort of
income but regular maintenance of the system will still be a hindrance with
multiple systems. Special care is necessary for the water control system as if the
watering control system were to fail; the plants would quickly die out.

As can be seen by the specifications of the project, hydroponics does have some
useful characteristics that can prove useful but issues such as expandability of
the growing method are a major concern for the implementation of the system in
the project. With the project specifications in mind, the hydroponics method of
growing seems to be a perfect candidate if the project designs can overcome the
faults. As such, aeroponics is the next growing solution to be analyzed.
Aeroponics is a growing solution that seems like it was derived from hydroponics.
Aeroponics does have some of the same properties as hydroponics where
nutrient solution is distributed through water. The key difference between a
hydroponics system and an aeroponics system is the medium at which the root
resides. For a typical hydroponics system, roots are supported by inert material
where water acts as the medium that helps to distribute nutrients and water to
the plants. In aeroponics however, the roots are supported at the base of the
actual plant. This solution becomes more interesting as it is observed that the
roots of the plants are suspended in the air by this conjecture.

The water and nutrients are treated in the same manner in that a nutrient solution
is generated through the using concentrations of nutrients and mixing it with
water. The distribution of the nutrient solution is approached differently however
by way of a spray mechanism with the sole intention of spraying the solution onto
the roots of the plants. Therefore, the use of the solution is controlled in a timely
fashion and excess water is dripped back into the container, which resembles the
recycling properties of the hydroponics unit. The distribution of oxygen into the

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roots for the hydroponics system was introduced by using an air stone and air
pump to create movement in the water such that it captures oxygen at the
surface at the tank. Because the aeroponics unit requires that the roots of the
plants must be floating in the air, there is no need to introduce an oxygen source.
One can certainly introduce oxygen into the system by way of using an oxygen
tank but according to the project specifications, the cost of an oxygen tank would
exceed the limits of the budget. For the purposes of this project, this
implementation would exclude the inclusion of an oxygen tank. Figure 2.3
displays the implementation of a typical aeroponics system.

As can be seen by the Figure 2.3, the aeroponics system has the similar
structure as the hydroponics system where the roots are enclosed. The roots of
the plants are suspended in the air where the top layer supports the stability of
the plant. The chamber in where the roots reside has a spray that acts as the
distributor of water and nutrients to the roots of the plants. By inference, the
water and nutrients that drip from the roots can be used again in the system
resembling the properties of hydroponics. With no support mechanism and the
roots residing in air as oppose to water, it is clear to see that the support of more
plants being able to grow increases with the implementation of an aeroponics
system. As can be seen in the diagram, a light source is used to provide energy
to the plants through the absorption of sunlight that is a biological process called
photosynthesis. For the cases of this project and for all implementations of the
growing system, a light source that will best simulate sunlight will be used to
provide the plants energy. More of the design implementations and decisions will
be discussed later on in the section.

What is also worthy to mention is that the nutrients and water spray can be
implemented as a mist system where the mixture of water and nutrients are
distributed by a plentiful series of small droplets, which are suspended in air. As
opposed to using a spray that would normally output water in a liquid form, the
advantages of implementing a mist distribution structure in the aeroponics
system leads to the system increasing the amount of nutrients that can be
absorbed with respect to the rate of absorption of the plants. The mist distribution
system will allow the plants to absorb the nutrients as the nutrients are given in
small quantities. However, problems such as over-watering that might become
an issue if the mist distribution is not controlled in a timely fashion. In addition,
because of the fact that the water and nutrients can be recycled through the
system, there would be no waste yielded from using a mist distribution system.
As such, a mist distribution system can be readily used in the aeroponics design
if needed. A spray mechanism can be found to be yielded cheaper as
components to control the mist distribution system can become complex.

There are many advantages to the implementation of the aeroponics system
such as little to no transmissions of plant diseases, low use of resources,
increased amounts of plants that can be grown as opposed to hydroponics, and



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                           Figure 2.3: An Aeroponics System
                     (Reprinted with permission from Aerofarms [2])

cheap implementation. Compared to hydroponics, the faults of hydroponics
where plant-to-plant transmission of diseases is increased and lackluster
expandability are not present in the aeroponics solution. Because the plants are
suspended in air in an aeroponics, there is essentially no medium present where
diseases can travel. In fact, most diseases will never occur because of the
conditions pertaining in the aeroponics solution cannot hold disease unless the
distributor is not sterile. With the necessary sterilization of the distributor, most of
the plants in an aeroponics system will not be afflicted with disease. If a plant in
the aeroponics system were to be afflicted with a disease, the plant can be
isolated from other plants in the system such that the amount of loss of plant life
is minimal as opposed to the shared medium systems like soil cultivation and
hydroponics. When compared to the other solutions analyzed for the project,
aeroponics stands to be the most plant sustainable solution because of this
unique attribute of being nearly disease free.

One of the many advantages of the aeroponics solution is the low usage of
resources among the system. As can be observed through hydroponics, the
characteristic of recycling water and nutrients through the use of a reservoir will
help to keep the usage of resources low. One main aspect of aeroponics that
cannot be achieved through hydroponics is the maintaining of low water usage.
In the hydroponics system, low water usage is achieved through recycling water
through the system but a substantial amount of water still needs to be used on
the basis of providing the medium for the system. Aeroponics does not have the
reliance of such amounts of water as there is no medium and the only water
being used is from the spray distributing system. Even if the water distribution
system is being used in the aeroponics system, aeroponics still has the useful
characteristic of recycling these resources for later use making it very efficient in
usage of resources. Even if water were to be used in the system, the aeroponics
system can be optimized such that the amount of water used is minimal
depending on the plants being grown. Compared to soil cultivation, aeroponics is
immensely efficient with respect to usage of water and nutrients.



                                                                                     10
It is also worth noting that the amount of electricity to manage a hydroponics
water flow control system would be immense when compared to the amount of
electricity it would take to manage an aeroponics system because the
hydroponics system is reliant on water as the base medium for the system. The
water flow must be constant for most hydroponic systems that use a net reservoir
with a central water control. With some hydroponic systems being reliant on an
air stone and air pump to provide oxygen to the plants in the system,
consumption of electricity only traverses higher. Aeroponics system does not
consume as much electricity as the hydroponics system given that the
aeroponics system is built with a mist distributor or a timed spray distribution
system. Most of the energy consumption for the implementation of this project
will be from the light source as there needs to be a steady source of light so that
the plants can absorb energy and nutrients at an optimal speed such that the
plants can thrive successfully. This is why it is best to minimalize the amount of
electricity consumed for the actual implementation of the solution. As one of the
projects goals is to have an efficient usage of resources with respect to the plants
yield, electricity consumption is a key issue. When compared with the soil
cultivation solution, even more water is necessary to provide nutrients therefore
even more electricity stands to be used in the system. With the comparison of the
following systems with respect to the management of resources, the aeroponics
system appears to be the most attractive solution for the implementation of this
project.

Another advantage of the aeroponics system is the amount of yield of usable
plants per unit time. The aeroponics unit and the hydroponics share the same
unique characteristic of producing more plants in a given time when compared
with soil cultivation. This attribute is very useful and pertains to the project
specifications in which the efficiency in which plants thrive must be high. The
reason why the aeroponics and hydroponics system share the same unique
capability of producing more plants is mainly because of the amount of nutrients
and water that can be distributed as oppose to soil cultivation where the roots
must gather the nutrients through the soil. Hydroponics holds the plants roots
through inert elements and water concentrated with nutrients such that the roots
will always have access to the nutrients it needs. Aeroponics does not have such
a medium however; the nutrients are applied directly at the root such that the rate
of absorption is increased. Because of this characteristic in the aeroponics
system, aeroponics will be able to produce an efficient demand of plants that can
be used or sold. The aeroponics solution also allows the roots of the plants to
have more access to oxygen mainly due to the lack of a medium if compared to
hydroponics where the roots are immersed constantly in water diluted in
nutrients. This means that the oxygenation of the roots is increased in the
aeroponics system therefore giving the plants in the system more sustainability.
This also explains why more plants can be grown in an aeroponics system
because some plants require more oxygen to survive.




                                                                                 11
The expandability of the aeroponics system is not as lackluster as the
hydroponics system mainly because of the fact that more plants can be
implemented in the aeroponics system as oppose to the hydroponics system.
This is mainly due to the fact that the plants in the aeroponics system have their
roots reside in the air whereas the hydroponics system has the roots reside in
water. Some plants are not able to thrive while the roots are placed in constant
contact with water because the plants need oxygen. This is not a problem with
the aeroponics system as the roots are suspended in air such that the plants are
not in constant contact with water but with the air. This means that the
aeroponics solution can accommodate for more plants due to this characteristic
such that the expandability of the solution is increase. There is however, a
limitation to this as some plants requires different nutrient levels. Because of this
and the definition of the system implementing a spray or mist system to distribute
the nutrients, a separate reservoir system will need to be implemented similar to
the hydroponics system. Nevertheless, since the size of the aeroponics system
can be smaller, having multiple systems for different plants will not be deemed as
a problem as compared to hydroponics. Therefore, the expandability factor when
compared to the hydroponics solution is increased. The cost effectiveness of the
system also affects the expandability factor. The materials and use of resources
expended on the aeroponics system can be implemented with respect to cost
effectiveness. The amount of resources such as water concentrated with
nutrients are used less in the aeroponics system whereas in the hydroponics
system, much more resources are used. Therefore, aeroponics is far more
expandable than the hydroponics system. Compared to the soil cultivation, the
expandability of the system is also lackluster due the fact that the amount of
resources are distributed inefficiently, the size of the soil cultivation is also large
due to the increase of the operations size with larger numbers of plants, and the
soil cultivation is not as cost effective as aeroponics since more resources are
wasted and are not used to efficiency. Therefore, the aeroponics system is
deemed to be the solution with the most expandability capabilities.

Despite all of the advantages for the aeroponics system as detailed above, there
are present disadvantages to the solution. One of the disadvantages is the
amount of complexity to the system for maintenance or implementation
purposes. When building the system, many components must be used and
maintained such that it requires technical skill. The aeroponics system is specific
in structure and has certain specifications for the system to be successful in
thriving plants. The functionality of the aeroponics system is not complex but
rather putting together the working components and maintaining components
given that there is failure among the system. The complexity does not escape
this level of the field but on a consumer level, it would be difficult to deal with the
system. With respect to then other solutions explored in this project, aeroponics
is the one solution that requires technical skill to implement. The technical
complexity of the aeroponics unit might be high such that the learning curve of
the system is steep but if implemented at this level, this will be a minor issue.
Maintenance of the system can also be often due to the fact that a spray

                                                                                    12
mechanism is used to distribute the water concentrated with nutrient solutions.
Because nutrients are present in the water, there is a possibility of that salts will
build up on the nozzles of the sprays. If the nozzles are blocked after a period of
time, the roots will not be able to receive nutrients such that the plants can easily
die. Just like hydroponics, if the distribution system fails, plants can fail in the
environment due to lack of nutrients and water being distributed to the plants.

Even with these downfalls for aeroponics solution, it feels more beneficial to the
project if such a system were to be implemented. Therefore, with the
specifications of the project in mind, the aeroponics solution is chosen for the
implementation of the growing system within this project. This is mainly due to
the many advantages that help the sustainability of the plant, the efficiency of
resource handling and cheap implementation of the solution. Although the
solution has its problems in maintenance, the advantages of the solution
outweigh the disadvantages such that it is within the scope of this project’s
specifications.

Subsection 2.1.b – Design Decisions and Parameters of
Growing System
With the choice of the aeroponics system as the growing system, certain
specifications and goals of this system must be defined. The goals of this
growing system are that the system must produce thriving plants in the most
efficient manner such that the sustainability of each plant is high, the system
must be efficient with the use of resources being distributed to the plants, and the
system must be inexpensive. For the aeroponics system, the resource
distribution to the roots of the plants will be in the form of a mist system
implemented by the use of nozzles that will result in the creation of high
pressures in the water. The bottom of the tank will be used as a reservoir for the
water such that excess water from the roots will be reused within the system that
increases efficiency in using resources. With water already being at the bottom of
the tank, the distributor will reside in this water and use it for distribution while a
concentrated batch of nutrients will reside at the top level of the tank to distribute
nutrients into the water.

The roots must be protected from light therefore; the tank will mostly be painted
black to prevent the transmission of light within the tank. Since there will be no
inclusion of an oxygen tank to save for expensive, a pipe will be used to
introduce outside air into the tank such that the roots can have access to oxygen.
This pipe will however be introduced at the top level of the tank and be
positioned downward in a right angle such that no light will be able to get in.
Additionally, a source of water will be introduced into the system through a pipe
in which a water level sensor will be needed to check the current level of the
water and a mechanism will be needed to control the flow of water. The nutrients
distributor that holds the nutrients concentration will be control by an electro-
conductivity meter which will measure the amount of elements are present within

                                                                                    13
the reservoir of water by way of measuring the resistance to electricity. If the
meter detects that the levels are too low, the nutrient distributor mechanism will
trigger and will initiate the drip of nutrients solution into the water. This process
will continue until the electro-conductivity meter reads acceptable values of
elements present in the water. The lighting system of the unit will need to use
optimal levels of power and be efficient in producing photosynthesis in the plants.
The light source can be an independent part of the tank system but will probably
be attached to increase the stability of the structure and will make for easy
transportation of the system.

The tank of each growing subsection will be drilled with holes wide enough to
hold net pots that will serve the purpose of supporting the plants at the base and
the roots will be suspended from the net pot.

Subsection 2.2 – Design & Research Related to
Light Source Implementation
This section of the project will analyze different light source implementations for
the growing system. Light is a very important source as plants absorb light into
their tissue through chlorophyll and produces energy within the plant through the
process of photosynthesis. Therefore, the best design implementation of a light
source must be used with the constraints of efficiency of absorption to engage
photosynthesis, power consumption, and flexibility of design. This section will
also cover the designing of the circuit to produce this light source with the best
possible power consumption.

Subsection 2.2.a – Comparisons of different light source
implementations
With the design considerations of the growing system, the light source is most
essential due to the fact that the plants being grown need light to supply energy
through the process of photosynthesis. This section will consider many design
considerations in the goal of achieving the most efficient light source to produce
optimal results for the thriving of the plants. Photosynthesis is the process that
supplies energy to the plants through the conversion of light, carbon dioxide, and
water into sugars and oxygen. This process is achieved by the plants taking the
light into the tissues of the plants where chlorophylls reside where chlorophylls
are molecules that reside in the tissue of the plant that allow the absorption of
light. Therefore, it stands to reason that the plants will thrive successfully with the
most optimal light source used that helps the process of photosynthesis. The
peaks as which chlorophyll can absorb the best amounts of light is in the
spectrum of blue (470 nm) and red (660 nm). Figure 2.4 shows the peaks of the
rate of absorption of light with respect to the wavelength of light. The plants to be
grown in this experiment have mostly chlorophyll A and chlorophyll B elements
whereas there might be come amounts of carotenoids. According to the peaks

                                                                                    14
displayed in the figure shows that all of these elements absorb blue and red light
significantly rather than the other colors among light. With the light sources in
mind, the most sought out light source for the purposes of this project will be
efficient use of energy, efficiency in aiding photosynthesis, and low cost of
material.




   Figure 2.4: The Rate of Absorption of Light with Respect to the Wavelength of Light
                                (Permission Pending [3])

It is also worthy to mention that there are four stages that a plant traverses when
growing. The four stages of growth are germination, vegetation, reproductive,
and senescence. Germination is the stage where the plant spouts from the seed
or clippings. It is basically the infancy stages of the plants growth. After this stage
of spouting, the vegetation stage is enabled where the plant starts growing
leaves and stems. The reproductive stage, also known as the flowering stage,
starts with the plants focus on producing seeds for reproduction. In this stage, the
plant has produced tangible vegetables that can be used. After this stage, the
plant has been matured and the growing process after maturity occurs. This
process is senescence where the plant is in its final stages of life. Knowing the
plant stages of growth is important with respect to the light source as a different
spectrum of light might affect the stage of growth significantly. For the focus of
the light source of the project, the main stages that will be taken into
consideration for design purposes are the vegetation stage and the reproduction
stage. This is mainly due to the fact that darkness is needed for the germination
stage and senescence does not aims of this project. For the light conditions in
the vegetative stage of the plants, blue spectrum light enables a better growth
cycle such that the plants will grow faster and be healthier. In the reproductive
stage of the plants’ life, red spectrum light yields better response such that
flowering is quicker. Therefore, the light sources that must be implemented into
the project must be able to produce red and blue spectrum light for faster
production of the plants. The lights do not have to produce red exclusively and
blue spectrum light as the production of light has many underlying elements of
light transmission contains a variety of different spectrums. As such, one of the
light sources that will be analyzed is the conventional incandescent bulbs.



                                                                                         15
Incandescent light bulbs are greatly known, as it was the original design for a
conventional light source produced from electricity. The light source produces
light with the use of incandescence, an emission of light from the heating of an
object. The light bulbs use a metal filament wire where the filament is heated
from inputted electric current. These light bulbs are very popular as they are used
in almost every light source application. Since the light bulbs are popular in
varied applications, they are readily available for use and can come in a wide
variety of sizes with different specifications, such as voltage usage and light
output, which can easily adhere to the project design. With respect to chlorophyll
absorption spectrum, incandescent light can produces a yellowish color that can
contain some of the wavelengths of red therefore can be used as a grow light.
However, since chlorophyll mainly absorbs blue, the absence of the blue
spectrums of light is a major flaw to using incandescent light as a light source for
the plants. Because incandescent light bulbs use a plenty amount of energy,
using these light bulbs in the project would yield wasted use of resources since
some of the light produced will not help the photosynthesis process as greatly.
There is also a greater generation of heat when using incandescent light bulbs as
a light source such that the lights will need to be placed higher to prevent any
adverse effects from the heat, Because of this increase of height, this diminishes
the efficiency of the light source further as the distance in which the light is
displayed is greater such that some of the light will not reach the plant as
efficiently. As there are no present blue light in the incandescent light bulb, there
will not be efficient absorption of light since most chlorophyll absorbs blue
spectrum light more optimally. The life span of the incandescent light bulbs of an
average 750 hours can also be limiting such that constant replacement must be
needed such that the ongoing cost of the project will increase. Although
incandescent lighting has been popular in many applications, fluorescent lighting
has been steadily replacing incandescent bulbs as of lately.

Fluorescent lighting is a form of lighting where as opposed to a filament is used
such as in incandescent lighting, mercury vapor is used to create light. The
inputted electricity creates an excitation on the mercury such that it fluoresces.
This is a departure from conventional incandescent light bulbs because of the
use of vapor to produce light. This method of lighting has been getting popular
and has been steadily replacing incandescent lighting due to lower electricity
usage and longer life. However, fluorescent lighting is costly for each
implemented bulb but this cost is usually equalized by the low energy costs.
Although incandescent lights are restricted to a certainly color production range,
fluorescent lights can produce a greater amount of color temperature such that
the light production will cover the spectrum for photosynthesis efficiency. The
fluorescent lights can have a significantly greater amount of life (averaging
around 20000 hours) when compared to incandescent bulbs (averaging around
750 hours). Fluorescent lights also do not produce as much heat as an
incandescent light source because of the lack of dependency on heat therefore
fluorescent lighting is not limited to the amount of distance that it needs to be
applied. This means that the light source can be fixated closer to the plants such

                                                                                  16
that the light produced will be absorbed to efficiency. Since there are more
selections in which spectrums of light and what color temperatures can be
produced by the light sources, fluorescent lighting can produce a great selection
of light such that the photosynthesis process is more than efficient when
compared with incandescent lighting. One of the drawbacks to using fluorescent
lighting is the high cost with respect to the selectivity of the light. Since this
project is aiming for optimal photosynthesis among the plants, the selection of
fluorescent lamps can be expensive even though there are greater
conveniences. In addition, since fluorescent lighting produces specific color
temperatures, two separate bulbs must be used for every sector of plant
implementations because of the need to produce red and blue spectrum light.

Another light source implementation that will be analyzed for the use in this
project is gas discharge lamps. There are many types of gas discharge lamps
such as high-intensity discharge (HID) lamps that come in the form of sulfur or
metal halide lights and sodium-vapor lamp that are available in high pressures or
low pressures. These lights all have an increased or equivalent efficiency when
compared to fluorescent lights and are much brighter with the correct
specifications. Metal halide lights are brighter and can produce light in the
domain of blue spectrum light. Because of its wide color temperature abilities, it
can produce a broader range of the light spectrum. However, red light cannot be
readily produced as the metal halide lights produce weak red spectrum light.
Therefore, an additional source must be used in combination with this light to
create an optimal lighting solution. With the use of high-pressure sodium light,
this method of lighting would adhere to the specifications of the project. Sodium
vapor lights are lamps that use sodium in excitation along with other elements
such as mercury to produce light emissions. Sodium vapor lights are known for
their low color temperature, which means that it will compensate for the
differences in the metal halide lamp settings where the color temperature was too
high. With the combination of both these lights, the specifications of the light
source can be achieved but there are disadvantages to using this setup.
Although the combination of both lights will yield a greater overall performance
over fluorescent light, the amount of heat produced from these lamps can be
overwhelming such that the lamps will need to be placed at a greater distance
limiting the project’s size constraints. Even with its superior performance, the cost
of this setup will be detrimental to the project and the power consumption of the
setup is not efficient. Therefore, the combination of metal halide and high sodium
lamps is not practical for the scope of this project. The use of low pressure
sodium lights is a possibility as it can yield lower power consumption but the cost
of the lamps can get expensive when expanding and there is still the problem
with heat production. Across all of the HID lamps, there is a low life span and in
some cases, when HIDs fail, they can produce damage if the ballast does not
catch it the lamp being empty.

The next implementation to be analyzed for the light source of the greenhouse
system is the Light Emitting Diode (LED). LEDs are semiconductor light sources

                                                                                  17
that used the property of electroluminescence with respect to the moving
electrons recombining with the holes at the junction. The color of each LED is
decided by the band gap of the semiconductor material. LEDs are known to be
very efficient with power consumption and very cheap with respect to the cost of
each LED. LEDs are small and portable because of the ties to PN diodes in
semiconductors. There is also no heat production from the operation of typical
LEDs meaning that the amount of distance between the plants and the lights can
be decreased such that the size of the project becomes desirably smaller. LEDs
are also very reliable in operation and have longer lifetimes when compared to
other light source implementations. Thus, it would seem that the use of LEDs for
the project would be ideal. However, there is a slight disadvantage that requires
more design considerations for LEDs to be implemented successfully into the
project. The issue being drawn here is that the LEDs will not output as much light
emissions as the other conventional light implementations. Because LEDs can
have different colors with respect to the material, the emissions of light with
respect to the most efficient spectrums that trigger photosynthesis can be directly
used therefore leading to the suggestion that the LEDs can trigger
photosynthesis more efficiently than other methods. However, because of the
power output of a single LED with a maximum amount of power such that the
LED will not trigger breakdown voltages, the amount of light produced can be
limiting. This can be solved by using multiple LEDs on the system but will
effectively raise the amount of power consumed within the implementation. If the
circuit was designed with the basis of efficiency, then the set of LEDs will
produce less power consumed. Therefore, LEDs will be used for the light source
for the growing system with a designed circuit that allows for less power used.

Section 2.2.b – Circuit Design for Light Source
The most important property of this circuit is to be efficient in power consumption
but the circuit must also be easily maintainable. For a simple circuit of LEDs, the
choice of a conventional series or parallel circuit seems logical but there are
problems with both implementations. In a parallel circuit, the LEDs are connected
in parallel with a power supply that will supply DC current. The best advantage of
this is that if one of the LEDs is defective, the circuit will still run, as the
connections to the power source are basically independent of each other. This
means that the circuit will be easily maintainable as the results of a defective
LED would be clear to see. Parallel circuits also has the useful properties of have
a uniform voltage in each branch with the total current being equivalent to the
summation of all the currents in each branch. This effectively means that if all of
the resistances in each branch are equal, the circuit will have an equal current for
each branch meaning that power is distributed evenly throughout the circuit. One
main disadvantage exists that goes against the specifications of the light source
implementation. This disadvantage is that the circuit will inherently use more
power if not optimized properly. More power would be utilized at each branch
because of the equal distribution of voltage in parallel circuits. Although each
LED will be at the most brightest emission of light, the overall reliability of the

                                                                                 18
LEDs life span will shorten if the proper current is not accounted for. Although
performance for each LED needs to be high, the reliability is also an important
factor as it increases and protects the sustainability of the growing system. LEDs
are sensitive to the amount of current that is supplied and if the wrong amount of
current were supplied, the LED would potentially burn up.

In a series circuit design, reliability problems would not be an issue as the current
along a series circuit is distributed even throughout each element in the circuit.
This means that the circuit can be designed with the most optimal levels of
current such that the LEDs’ lifespan will not be affected. Current can be
controlled easily with a series circuit as oppose to a parallel circuit because in a
parallel circuit, the impedances of each independent branch determine the
current within that branch. Therefore, the overall current distributed within the
circuit is addition of all currents in each branch. If the impedances are not
controlled in equality, current between two branches would be different and
therefore the overall current would not be as controlled. Series circuits can have
easier control over the amount of current is distributed within each component of
the circuit. However, there are disadvantages to using a series circuit for the
implementation of this light source. One of the disadvantages of using the series
circuit is that the distribution of voltage within the circuit is not uniform such that
the performance of each LED would be halved for each sequential LED after the
original. Because of this, the voltage in the series circuit must be high enough
such that it can supply enough voltage for good light emission. The other
disadvantage to using a series circuit is that the circuit will eventually fail due to
each component being dependent on the connection of the last component. If
one component were to fail in the circuit, there would be no clear indication to
which element is the reason for operational failure. This would go against the
specifications for the project being easily maintainable. The circuit must also use
a DC power source to improve the reliability of the active circuit elements in the
circuit. If an AC source is used, the circuit would need to be able to
accommodate the LED in such a way such that they can operated safely. This is
mainly due the fact that the current in an AC circuit would not be constant and
could potentially go over the threshold of safe operation current. Therefore, the
power supply of the light source must also be a DC power source because the
LEDs can correctly operate.

With the aspect of the specifications for this project, simply implementing a
parallel circuit or series circuit would not be a wise design decision therefore a
circuit should be designed using the properties of both circuits such that the
project goals can be met. This can be achieved by using the properties of both
circuits and implementing the same perspective on each element. The key goal
for this circuit is to be easily maintainable and to utilize less power consumption.
The circuit must also observe the safe parameters in running the LEDs, as their
reliability is crucial to the sustainability of this project. For safe operation of LEDs,
the current must be controlled and be smaller than the maximum forward diode
current. Resistances must be chosen to control the current and voltage as well

                                                                                      19
as prevent a short circuit to the power supply of the circuit. One idea is to create
a fusion of both circuits such that current can be controlled throughout the circuit,
the performance of the LEDs are optimal, and for the circuit to have low power
consumption.




                    Figure 2.5: Circuit Diagram of Proposed Circuit

Figure 2.5 shows a designed circuit with this idea in mind. As can be seen by the
figure, a resistor is connected in series with the DC source and a load is
connected in series with resistor R. he purpose of adding this resistor is because
it will control the amount of current travels with respect to the equivalent
impedance of the circuit. This load will consist of a network of LEDs where the
supplied voltage to that network is a voltage divider of the source voltage and the
impedances of the networks. Using the circuit in figure 2.5, the current can be
controlled across the network such that the only concern is the network of LEDs
and its impedance. The impedance of the load network must be low so that the
network does not have control over the impedance of the circuit. This however
has the effect of consuming some power, as resistance R must be able to
produce enough resistance such that the circuit does not short. This network is
simple in design as it would only require 50 resistors and 50 LEDs for each
branch but the complexity of the circuit is too high due to the fact that the size
constraints of the circuit become overwhelming. In addition, with this circuit, it is
deemed that too much power will be wasted on each connecting resistor, which
is necessary for each branch to control the amount of current that will be used in
the load network. It is also observed that the voltage consumed by the first series
resistor. This can be solved by switching the positions of the network of LEDs
with the series resistor but the circuit’s complexity is still too high with the high
multiples of LEDs. Below in figure 2.6 shows another proposed design using a
fusion of series and parallel concepts. This will be the decisive design of the LED


                                                                                  20
light source circuit in which the resistances value R and the voltage V will be
designed according to the circuit specifications.




                    Figure 2.6 – Light source schematic diagram


                                                                            21
As seen in the circuit displayed in figure 2.6, the circuit uses parallel branches to
distribute voltage while each branch consists of a series network of LEDs with a
resistor attached at the end. This circuit uses the distribution of voltage as the
same in each branch for the LEDs to function properly while the series network
within the branch will help control the current flow between each element. As with
the previous circuit in figure 2.5, each branch required one resistor and one LED
leading to the amount of materials summing up to 51 resistors and 50 LEDs. With
this series circuit implementation in each branch for the circuit displayed in figure
2.6, only one resistor is used in each branch with 50 LEDs being implemented
across each branch evenly. This means that the new designed circuit uses fewer
materials and is therefore cheaper. This means the newly designed circuit
adheres to the specifications of project in that low cost is a goal. It is also worthy
to note that the circuit displayed in figure 2.5 has less voltage control and
therefore uses more power than the circuit in figure 2.6 due to the fact that only 5
parallel branches are used in the present circuit whereas the previous circuit had
50 branches. Although the maintenance of the previous circuit was easier due to
the fact that the branches are independent of each other, the maintenance of the
new circuit is clear to see as if one LED is defective in one of the branches, only
one of the branches will be disabled. This does mean that the circuit would
require the testing of at least 10 diodes per defective branch as a worst-case
scenario however. The series resistor in each branch will control the current
flowing between the LEDs such that resistance value can be chosen such that
the LEDs can operate at safe levels of current. This circuit has a better spread in
voltage distribution while keeping the voltage ratings at a stable level. If a
network of 50 LEDs cascaded in series with one resistor would require potentially
200 volts, which would be unstable for the scope of this project.

The resistance values chosen for both perspective LED light sources can be
chosen to control the current all the while keeping the current flow at low levels.
For the chosen red LEDs that will be used in the experiment, the forward current
ratings for the LEDs are 30 mA where the operational voltage ranges from 1.7
volts to 2.6 volts. For the network of LEDs, this will mean that the approximate
value to be used for the voltage source will be 22 volts where each element in
the series network will consume an average of 2 volts. For the LEDs to be
supplied with safe levels of current, the resistor chosen must be more than 680 Ω
so that the voltage in the branch does not except the forward current. This new
designed circuit can operate in a stable mode of operation without hazard to the
components used within the system. However, blue LEDs will require much more
power due to their operational voltage ranges being much higher than the red
LEDs. The operational voltage ranges for the chosen blue LEDs are 4.5 volts to 5
volts which means that if the current circuit were used, the voltage source would
have to be 55 volts which is a huge increase with respect to red LED circuit’s
voltage source. Building a higher voltage DC power supply would require
different requirements and components such that the cost of materials will
increase. This means that a modified version of the circuit will be required for the
voltage source to remain stable for a light source circuit implementing blue LEDs.

                                                                                   22
Below in figure 2.7 is the new designed circuit that will serve the purpose of
running blue LEDs.




                 Figure 2.7: Schematic Diagram of Blue LED circuit


                                                                           23
The circuit displayed in figure 2.7 still uses the same properties as the previously
designed circuit that will be used to power the red LEDs. As can be seen, this
circuit has more branches, higher rated resistors, and only 40 LEDs as opposed
to 50. The types of blue LEDs that will be used are known for their high
performance with respect to the luminous intensity, which explains the reason
why a larger amount of voltage is consumed for these LEDs. With this circuit,
only 5 volts will be consumed by each element in the branch that will provide for
safe operation for each LED present in the circuit. The equivalent resistance
value for each branch must be higher because the chosen LEDs have a forward
current maximum of 20mA therefore the current must be lower for more stability
in each branch while the current must be enough for the LEDs to be active. For
this circuit with the currently selected resistors, the amount of current that will be
flowing in the branches will be around 18 to 19 milliamps which is close to the
maximum forward current to ensure that the performance of the diodes are high.

The power consumption of the circuit would approximately average out to be
4.75 watts with the assumption that the amount of current flowing through the
branches is 19 milliamps and the voltage source is producing constant 25 volts to
the branches. Despite the higher voltage requirements with comparison to
average LEDs, the amount of power consumed by this circuit is much smaller
than a fluorescent or incandescent light source showing that the implementation
of this circuit is indeed the correct approach with respect to the project’s
specifications. If the red LEDs power consumption ratings were observed, it
would average to be 3.3 watts if the current flowing through each branch is
assumed to be 30 milliamps and the voltage were to supply a constant 22 volts to
each branch uniformly. This leads to the amount of power consumed for the
entire light source implementation to be 8.05 watts, which is departure from other
light source considerations. The power consumption of the LED networks can be
greatly reduced if necessary by raising the resistance value thereby decreasing
the amount of current that will flow through the branch but this would increase the
amount of voltage that will be applied to the resistor, which would cause
unnecessary heat present in the circuit. Heat generation in the circuit is also a
considerable issue when using LEDs as heat can decrease the amount of life
span by degrading the junction of the diode therefore the amount of heat used in
the circuit must be controlled.

With the current setup of the project, there will be two prospective circuits that will
be implemented for the light source design. However, the components involved
in creating two separate DC power supplies will be costly to the experiment and
will create conflicts with the project specifications. This can be solved by merging
the two circuits into one by using only one DC power supply such that the cost of
materials would be manageable. Because of the different amounts of voltage
needed to power both blue and red LEDs, there is a need to finding the amount
of voltage that will enable both circuits to work successfully. Because of the
forward voltage ranges of the red LEDs, the chosen 25-volt source can be used
to power the circuit but will require the need of increasing the resistances used in

                                                                                    24
the circuit because of the increase of current resulting from the new voltage
source. In figure 2.8, the final schematic is displayed with the chosen resistance
values, positioning of LEDs with respect to the color, and the voltage source
supplied. The total power consumption of the final circuit is 7.93 Watts, which is
lower than having two separate LED networks. This circuit saves costs for the
budget because of the use of only one power source and the minimal use of
resistors. The amount of stability within the circuit is high because the current is
controlled with respect to the resistors making this circuit run in safe operation
with minimal maintenance to be worried about because of the properties of
parallel networking.




            Figure 2.8: Final LED schematic for Light Source Implementation


                                                                                 25
Subsection 2.3 – Research and Design related to
Nutrients Detection and the Distribution
This section will discuss about the nutrients distribution and detection techniques
to be implemented into the growing system. The nutrients detection system is an
electrical network that will aid in detecting the presence of nutrients present in the
water reservoir. When the system detects the lack of nutrients in the reservoir,
the nutrients distribution system is enabled thus releasing nutrients into the
reservoir such that the water will be diluted with a concentration of nutrients. The
detection system will still be enabled such that the nutrients distribution system
will remain on until the detection system will send a signal to deactivate the
distribution unit. Thus, the systems will be designed with the same principles of
the project such that the design will adhere to the specifications of the project.

Subsection 2.3.a – Nutrients Detection Research and
Design
The nutrients detection system can be built around the principle of electro-
conductivity where the resistivity of the water will determine the amount of
conductive elements is present in the water. With this property, it is easy to apply
this into the form of an electric circuit, as there are many circuits with the sole
purpose of detecting resistance. With conventional electro-conductivity meters,
they measure the resistivity of the water with an inputted current at the probe.
Some electro-conductivity meters measure the electro-conductivity of the
medium with respect to other parameters such as pH level and temperature.
While temperature and the many other factors measured by these meters will be
useful information that can lead to the optimization of the growing system, the
cost to build such a circuit would be too complex. To keep the circuit as simple as
possible and with the goal of low cost, the designed electro-conductivity meter
will be measured with respect to the resistivity of the water supply such that the
circuit will only be dependent on one parameter with respect to the reservoir of
water.

Figure 2.9 displays the schematic of the proposed design for the electro-
conductivity meter. The circuit in figure 2.9 uses a feedback gain amplifier where
the first resistor is replaced with a probe. This probe will reside in the water of the
reservoir where it will return back into the operational amplifier. This is essentially
passing the current through the water where the water is acting like a resistor.
The amplifier will amplify the signal with respect to the resistance of the feedback
loop over the resistance of the water obtained by the probe. The input signal can
be an AC source set to unity gain, which can be implemented into the circuit
through a DC to AC converter using the current DC power supply. What will
come out of the feedback gain amplifier is the signal amplified which will indicate
the level of nutrients within the water. If there are more nutrients present in the

                                                                                    26
reservoir, the amount of resistance in the water will be decreased because of the
presence of more metallic elements, which would be the nutrients therefore
leading to the conclusion that there are more concentrations of nutrients. If the
resistance of the water is higher, then the concentration of nutrients present in
the water will be less. Therefore, this premise leads to the relationship of there
being a much more amplified signal coming out of the feedback gain amplifier
with a smaller resistance in the input resistance and there being a much smaller
amplified signal with a larger resistance. This is reasoned by the properties of the
output gain of the feedback gain amplifier that results in the amplification of the
signal with respect to the feedback resistance divided by the input resistance
plus one. Since this schematic uses the positive setup of the feedback gain
amplifier, the returning signal will be positive.




           Figure 2.9: Schematic Diagram of the Nutrients Detection System

The next stage of the circuit is an AC to DC converter that will serve the basis of
converting the AC signal given from the feedback gain amplifier and converting it
into a DC signal. This will stage of the circuit will create a nominal value for the
gain differences and allow for the results to be differentiable with respect to the
resistance of the water. With this conversion, a relationship can be formed to
determine the amount of concentration of the nutrients will be present in the
water through approximation. The goal of this nutrients detection system is not to
be as precise but have some accuracy within a certain margin for the
coordination of the system when dealing with nutrients distribution. The lack of
focus and emphasis given to precision can be justified by stating that the water
will not be over-concentrated with nutrients by small deviations. The dilution of
the water with the nutrients system happens over time and over dilution is less
than likely, as the nutrients distribution system will only provide small amounts of
nutrients in a given time. Therefore, close precision is not the main focus of the
nutrients detection system but accuracy is needed within a certain margin. This
margin can be defined with respect to the needs of the plants. Because different
plants are grown in the system, different nutrients levels are needed for optimal
results.



                                                                                 27
Therefore, the level of nutrients needed in a given reservoir of water is
dependent on the plant being grown. Because of the possibility of all these
plants, separate blocks of growing units will be needed for plants with differing
needs. With a whole section of plants that require the same amount of nutrients
and water, the nutrients distribution system will need to be customized to fulfill
those requirements. All of this customization of the set by a circuit that will be
interfaced with the nutrients distribution unit. This circuit will need to reside right
after the AC to DC conversion stage and will be connected right into the nutrients
distribution system thus enabling the distribution process. This circuit will have to
take in the voltage and compare the voltage to another chosen voltage using the
relationship gathered from the resistivity of the water. In this case, a voltage
comparator can be implemented within this design as the behavior of a voltage
comparator models this behavior. A voltage comparator will take the difference of
two input voltages and outputs the difference in voltage. For this implementation,
a preset voltage is set as the cutoff point for the nutrients distribution system and
if the voltage from the AC to DC converter is smaller than this preset voltage, a
negative voltage will be outputted from the voltage comparator. Since the voltage
is smaller than the preset voltage, the nutrients distribution system will be turned
on to increase the output voltage. Once the outputted voltage reaches the level
of the preset voltage, the nutrients distribution system should be turned off at this
point. To optimize and simplify the operation of the nutrients distribution circuit,
the voltages will be flipped such that the preset voltage will be set to the positive
terminal and the output of the AC to DC converter will be set to the negative
terminal such that the result for turning on the nutrients distributor would yield a
positive voltage. Another voltage comparator can be used for the modeling of the
behavior of making the nutrients distribution system active or fully off by using the
same property. Thus, the connection to the nutrients distributor can be
implemented as a voltage comparator, which compares the preset voltage with
the voltage outputted from the AC to DC converter. Therefore, the nutrients
detection system will return the difference between the voltages and output it into
the nutrients distribution system.

Subsection 2.3.b – Nutrients Distribution Research and
Design
The design of the nutrients distribution system is dependent on the design of the
nutrients detection system. With the designed nutrients detection system
returning a voltage difference between the preset voltage and the voltage with
respect to the resistivity of the circuit, the nutrients distribution system will need
to use this voltage to turn active or fully off. Using the same properties to find the
difference of the between the preset voltage and the outputted voltage with
respect to the resistivity of the water, another voltage comparator can be used
which would be connected right after the nutrients detection system. Because the
voltage difference is outputted, a defined voltage can be used to reference the
state of turning the circuit inactive or active. However, it can be observed that the
only time the nutrients distribution system will turn on is when the outputted

                                                                                    28
voltage is positive such that this amount of voltage can be used to power the
nutrients distribution switch. This will however leave the possibility that the circuit
might have too much voltage such that severe damage to the overall circuit is a
possibility. Therefore, a voltage regulator will be used to control the voltage within
the system with the outputted voltage from the voltage comparator unit. The
desired functionality of this circuit is that it will essentially turn on when the
threshold voltage is passed and turn off if the voltage is too low. The voltage
regulator can be constructed by using series resistors and diodes to control the
flow of voltage going through the system.

Having the input voltage higher will just mean that the circuit does need to be on.
This circuit will regulate the amount of voltage is distributed into the circuit to
prevent damage from occurring. The regulator will be connected to a circuit that
will control mechanisms for the control of the nutrient drip system. When the drip
system is activated, the nutrient concentration will be distributed into the water by
small drips. The system will keep on dripping nutrients concentration into the
reservoir until the nutrients detection system supplies a voltage that is lower than
the threshold of the voltage regulator indicating that the resistivity of the water is
in acceptable ranges, which is significant because that means the accepted level
of concentration of nutrients is present in the water. This part of the circuit, where
the nutrients distribution resides, will be controlled by an electronic valve, which
will slowly distribute the water into the system. This electronic valve is called a
solenoid valve where the current applied to the valve will create a magnetic pull
towards the magnet and enable the flow of the media. Figure 2.10 illustrates the
functionality of a generic solenoid valve, which will be implemented into the
project.




                 Figure 2.10: Functionality of a Generic Solenoid Valve
             (Reprinted under Public Domain from Wikimedia Commons [4])

As can be seen by the diagram, the current applied by the solenoid controls the
flow of water by the pressure relief conduit where the conduit will depress such

                                                                                    29
that water flow is no longer restricted. If the applied current is no longer present,
the conduit is depressed back to its original state due to the lack of magnetic
force on the solenoid. This component is perfect for the implementation of the
nutrients distribution system, as only two components will control the system, the
voltage regulator and the solenoid valve. As can be seen in the block diagram of
the nutrient distribution system located in figure 2.11, there a few components
such that the basic circuit structure is simplified.




                   Figure 2.11: Nutrients Distribution Block Diagram

The nutrients distribution system adheres to the project’s goals of keeping low
power consumption design while keeping the use of materials lowered to keep
cost low. Although the solenoid valve might be steep in price with respect to
other components located throughout the project, the cost is manageable due to
other components in the circuit. With both the nutrients detection and distribution
system designed, the growing system can maintain being fully automated with
respects to feeding and watering the plants in the system leading to the premise
that the system will have minimal maintenance, which adheres to the
specifications of the project.

Subsection 2.4 – Water Management Design
This section will discuss the water management design of the growing system
where a single circuit will be tasked to detect the amount of water is present
within the reservoir and the water will be refilled if necessary by pumps. The
water level detection circuit will use a low voltage dc power source that will be
connected to a probe. This probe will be located on the wall of the reservoir and
will be placed at an acceptable level that will be deemed the maximum height of
water in the reservoir. The probe will be covered so that measurements on the
water’s level will not affected by the water outputted from the mist system. The
designed circuit will consist of a low voltage DC source into an open circuit. The
probe will complete the circuit when the water level reaches high enough. At this
point, the circuit will stop the water pump from filling up the reservoir. The water
pump will pump water into the reservoir until the maximum height is reached
thereby supplying a constant supply of water if the reservoir goes low.

                                                                                  30
This will mean that the water pumps will need to operate with a second solenoid
valve to control the flow of water with respect to the amount of current and when
the circuit for the water detection system is closed, indicating that the height of
the water has reached an acceptable height, the detection system will signal the
solenoid valve to turn off. This can be implemented through the use of a voltage
comparator between the immediate water pump system and the water level
detector. Because of the use of a low voltage source to enable the water to be
safe among materials in the system, an operational amplifier will be needed to
amplifier the signal such that the voltage comparator will receive the correct level
of voltage to enable a shutdown of the water pumps. There might be some
problems with overfilling past the maximum height line as some of the water will
be suspended in air for the most part therefore a delay might be added to help
compensate for the issues in accuracy. The implementation of the delay unit is
not necessary if overfilling becomes an issue therefore more testing must be
conducted to verify if that is the case. The negative terminal of the comparator is
connected to a DC source that will supply the solenoid valve enough voltage to
enable the flow of water. Figure 2.12 shows the schematic diagram of the water
management circuit as explained in this section.




            Figure 2.12: Schematic Diagram of the Water Management Unit

When the water reaches the maximum height, the probes will complete the circuit
with the water in between and produce a voltage into the feedback gain amplifier.
This amplifier will increase the gain of the low voltage to the specified voltage
needed to run the solenoid valve. Because the feedback gain amplifier is set up
in the negative position, the voltage returned will be the negative voltage of the
power source to the solenoid. Thus, the difference between these two voltages
becomes zero therefore the solenoid valve will be shut off, which will cut off the
flow of water to the reservoir. This circuit will handle most of the water
management in the growing system automatically without the need for user

                                                                                 31
interaction. The only maintenance required for the watering system would be the
refilling the external water supply although this can be implemented with using
utility based water because of the control of the solenoid valve. This would
however require more intricate piping to ensure water pressures are at a stable
level and the water pressure does not affect the solenoid valve.

Subsection 2.5 – Test Procedures for the Growing
System
The testing of the growing system will require a much more intensive testing of
the components of the system as there are many active components present in
the circuit. For the testing procedures, each type of component will be tested for
safe operation and stability. The light source circuits, which are implemented by
LEDs, will be tested and verified for the functionality. The most important factor
about testing this circuit is to keep the stability of the LEDs high by controlling the
current. Therefore, the LEDs will be observed quite carefully during the testing
process. The testing procedures for these circuits will eliminate the need for
observing the current problems during operation thereby reassuring the stability
of the circuit. The test for the LED circuits will be conducted by first using a 1 kΩ
resistor and testing it in series with the LED and a power source. This will first
ensure that the LED is working and the performance of the LED is stable. The
resistor value will drop close to the point where the forward diode current
maximum will occur within this test circuit. If the LED survives the test, the
specifications of the LEDs are correct and therefore can work in the circuit. If the
LED does indeed burn up, the circuit will require resistance changes as well as
voltage source changes to control the current. When the LEDs pass this test, the
series configurations used in the light source design will be used as a test circuit.
The circuit will be observed for the amount of light each LED illuminates to verify
that the correct amount of voltage is applied and the current is once again
observed to verify that the amount of resistance used in the branch is correct.
Once this test is finished and corrections are made if necessary, the light source
circuit is verified for functionality and the test is finished. This test procedure
serves the purpose of checking the functionality of the circuit and the stability of
the components. If any necessary changes are needed for any of the circuits
present in this project, the test procedure must verify that the changes work such
that the changed of the project can be implemented into the final stages without
any conflicts.

For the nutrients detection system, the system will be built on the premise that
the preset voltage is chosen by an arbitrary but attainable value. With the circuit
built, the circuit’s components will be test for functionality and the outputs will be
verified. The probes will then reside in water and the output relationship of the
circuit will be observed with respect to the addition of nutrients to the water. The
test nutrients used can be table salt since it is a compound made out of metals.
With the output relationship developed, the circuit can now be used in the

                                                                                    32
growing system with realistic concentration values. This circuit will be fully
realized and tested again using the same method and another test will be
conducted on the actual growing system with nutrients solution being used
instead of salt. Another electro-conductivity meter will be used to verify the
results of the circuit.

With respect to the nutrients distribution system, the nutrients detection system
will not be involved in the first stage of testing. The functionality of the circuit will
be verified and tested by testing the built circuit and ensuring the stability of the
active components. With this test successful and corrections made if necessary,
the circuit will be fully integrated with the nutrients detection system where water
and table salt will be used as the medium. If this test is successful, full circuit will
be placed in the growing system and will be tested with actual nutrients solution.
With the functionality and the connectivity between both circuits verified, the test
can be deemed successful.

The next system tested is the water management unit which is going to require
some safety equipment because of the fact that a short circuit in the probe with
water is used as an element. Because the dc power supply is directly connected
in series with this open circuit, great care must be put into place such that no
injuries can occur. Although the power source will be tested at low amounts of
voltages, the current can possibly still be high enough to do damage. The active
components of the circuit are first tested separately and are verified for their
functionality. The outputs of the overall circuit are observed and are verified with
the theoretical behaviors of the circuit. The solenoid valve is tested with the
circuit to observe whether the correct amount of voltage and current is being
applied to the valve so that the flow can occur. After all the verification of this
circuit is finished, the circuit is applied with probe to verify the functionality of the
circuit and safe operation of the short circuit with water. With the test verifying the
safe operation of the circuit, the circuit can be deemed successfully built.

The next test will be conducted on the actual growing unit where the components
of the system will be tested in a traditional manner. The components such as the
mist system are verified to be functional in the present growing container with the
water reservoir. The container will then be tested for any leaks or holes to ensure
that there will be minimal resource loss. To test the actual operation of the
growing system, the growing system will be tested with only the mist system and
a conventional light source. An easily grown plant such as dollar weed or basil
will be used to verify that the system can be able to grow and sustain plants in
the environment. Since this test actually takes longer, the growing system will
need to be tested first so that the time constraints of the project are not affected
by the testing procedures. If the plants are able to sustain life in the growing
system, the growing system will be cleaned thoroughly and will be used as a
medium of testing other components that are in that testing stage. If the growing
medium is able to function with all the systems implemented, the growing system
is verified to be working and the project can progress.

                                                                                      33
The ordering of the testing of these components within the growing system is
crucial due to time constraints as some components are dependent on the other
and some tests inherently take longer than most. The first test to occur will be the
testing of the growing medium since it takes longer than most other components
test. While this first test is being conducted, the LED light source test will occur
as it takes longer than others and is not dependent on the growing system. All of
the other systems such as the nutrients distributor, nutrients detector, and the
water management system will be tested up to the stage until the use of the
growing medium is necessary to carry out the test. With the testing of the
growing medium completed, the other systems are tested within the medium
separately and are verified working with the growth system. After all the systems
are tested separately, the system is connected together and is tested. With this
test completed, the project can be continued and constructed to the final stages
with the specific changes if necessary.

Tests must also be conducted on the interfacing between the systems in the
growing systems and the systems that reside in the other parts of the projects
such as the power supply units and the central control unit. The power supply
units will produce enough energy to run most of the systems within the growing
system such that the power supply’s functionality is crucial to the operation of the
growing system. With the power supply tested, the interfacing between the
system and the power supply needs to be tested for any differences in voltage
and current supplied within the circuit. The power supplies need to be in the
mode of operation of providing DC power to the circuit because most of the
circuits designed in the growing system requires DC power. Testing the
connections between the central control unit and the growing system is crucial
due to the fact that the central control unit only takes in inputs of ones and zeros.
Therefore, if the wrong amounts of voltage get sent to the central control unit,
there will be grave issue with the materials used in the central control unit due to
the excess load. Therefore, the outputs must be tested and verified.

Subsection 2.6 – Conclusions reached in
Designing the Growing System
With this system growing system being implemented under the basis of low
power consumption, inexpensive use of materials, and low maintenance among
the system, the current design of the system adheres to these specifications.
Although some materials within this part of the project can be costly, the cost is
manageable because of the low cost of the other components. It is observed that
more expensive aeroponics systems exist in the consumer market that will
definitely work but this project implements the same system in a much cheaper
fashion. Although there were more efficient ways for things to be built within this
design, most of those approaches went against the specifications of this project
with most of the approaches being too expensive. Overall, this growing system
will be able to thrive plants within the system.

                                                                                  34
Section 3 – Design and Research Related to
Smart House Controls
Subsection 3.1 – Smart House Definitions and
Ideology
Have you ever experience the feeling of forgetting to turn off the lights, air-
conditioner or even an appliance as important as stove. These are some of the
things that the general population thinks about when they are on their way to
work, vacation or school. So why do these thoughts come into mind when the
focus of attention should rest on other more important aspect of life. The answer
of course varies with each individual; it could be for financial reasons such as
saving money on the electric bill, to something as serious as preventing the
house from catching fire due the stove being left on. Smart house provide the
answer to these problem and they provided much more benefits which would
help simplify everyday life. Since the basis on building or upgrading to a smart
house is to make the life of people less stressful, efficient and enjoyable it’s
appropriate to mention how the smart house ties all of this together. The smart
house uses home automation in other to connect all of your electronic devices
together. All of the devices connected to this home network could be control in
such a way to be automatic and useful for the person or family. The smart house
could be set up so that a light or TV turn on or off depending if the person walks
into or out of a room; to automatically set the night lights and check door looks
when it gets dark and at a certain time of day. All of the devices could be check
and control from the comfort of a central control unit that’s close by or even
through the internet. Of course checking the smart house would depend on how
complicated the smart house system is set up to be. Besides just being able to
control the lights of the smart house there are also additional device which could
be set to turn/off automatically. Some of these appliances are hot water heater,
stove, microwave, computer screens and home entertainment systems. The
benefit of turning off these devices when not being use is to safe energy which
also lowers Carbon Monoxide emissions and thus makes the world a better place
to live.

So why is it so important to turn off (unplug) devices when they are not in use?
The answer lies on devices which are in a state called standby mode. According
to The Lawrence Berkeley National 5% to 10% of a house electric bill is due to
electrical devices being in standby mode. So what is standby mode? And how
can it be prevented? Mainly standby mode transpires for two separate reasons.
The first is that when a device is turn off or not performing their primary function
the device still draws power due to the power supply still losing energy when it’s
converting alternating current to direct current. The second reason why devices
consume power is that they are not truly off due to their design. An example
could be a television; a television set is always drawing power due to the Infrared

                                                                                 35
sensor. The Infrared sensor and the microchip are always on since they are
waiting for the signal in order to turn the television completely on. Figure 3.1
shows the average power consumed on standby mode in different devices found
around the office. All of these appliances seemed to use low wattage
consumption, but they still add up to be around 5% to 10% of the electric bill.




          Figure 3.1: Measurements of Electronic Devices on Standby Power
      (Reprinted with permission from Lawrence Berkeley National Laboratory [5])


Subsection 3.2 – Similar Technologies
Subsection 3.2.a – Smart Power Strip
There are several simple technologies that are being used in the market in order
to lower the energy being wasted on idle power (standby). The most common
found is the called a smart power strip. Smart power strips work by measuring
the current that is drawn when the device is fully on and when the device goes

                                                                                   36
idle. After a predetermine amount of time, of the system being in on standby the
power strip completely cuts off power to all of the outlets expect for the control
outlet. The control outlet is not cut off from power since the measurement of
current passing through that outlet is needed in order to turn the other outlets on
when the main electronic device is turn on. One draw-back about power strip is
that each individual outlet cannot be control on or off when desire but instead all
of the outlets turn off simultaneously. Smart power strips provide three functions,
which are protection against voltage spikes, power saving feature and adding
power outlets. An example of a power strip is called the Energy Saving Smart
Power Strip which cost around $30.

Subsection 3.2.b – Timers
Another stand-alone Smart Home device is the outlet timer. This device works by
selecting the time in which you want to allow electricity to pass to the electronic
appliance. Figure 2 shows the Programmable Heavy-Duty Timer which cost
$19.99. Its main features included: Heavy duty switching - 15 amp maximum
load, fourteen 14 programmable on/off events, LCD display and a random on/off
mode for vacation purposes. A down side to this device is that it will execute its
on/off functions even if the customer is using the device. An example could be
when the customer is watching a movie late at night where the device had been
program to turn off at that moment in time. This could very frustrating experience
and a big inconvenience to the customer which would make the smart house
seem not as smart. A way to fix this problem would be to somehow sense when
the person is using the electronic device and avoid turning it off until the user has
finish using the appliance and a certain amount of time has pass. Then the timer
could go ahead and turn the device off.




          4" x 2 3/8" x 1
          ¾" (2 ½"
          including plug)




                             Figure 3.2: Example of Timer
                               (Permission Pending [6])

The Digital Thermostat is one of the main features that are incorporated in Smart
Houses. The objective of the Digital thermostat is to measure the temperature
inside the house and maintain a range defined by the user. Since the thermostat

                                                                                  37
controls the air conditioning which consumes a lot of power, it is defined as being
very important control in order to reduced energy being wasted. The price for
Digital Thermostat Range from $25-$200 depending in the complexity and
manufacture selling the unit. Most digital thermostat controlling the Air
conditioning Unit by turning it on or off at different times. The time is control by
the customer setting times and temperature desire for the week. The downside in
just controlling the AC unit this way is that the systems fails in the compartment
of saving energy. By not being able to detect the presence of a human begins in
the house and changing the setting in order to operate under the best energy
saving conditions the unit waste a lot of energy that could have been saved.

Section 3.3 – Smart House Security
One featured that many smart houses incorporate are security system. The
Security feature of the Smart House is sometimes seen as one of the most
important aspect of a Smart house since many people benefit from the ability to
relax knowing that their house is safe and secure. There are several different
methods in which smart house security systems are implemented. These
methods range from professional level, where a company is paid to monitor your
house and alert the correct authority; to a basic alarm system in which you are
able to see a camera placed somewhere else on the house. There are also
systems which detect the presence of smoke or gas and notify the Firemen and
the people inside the house so that appropriate steps can be taken. The benefit
of combining the security aspects with a smart house is that it enables a regular
security system to be more beneficial to the customer. A simple illustration could
be seen as follow, imagine that a customer buys a low level alarm system which
would go off in case an intruder enters. This system will work by settings sirens
off inside the house. But the basic system would fail to notify the customer of an
intruder in the house and therefor would not be as efficient. In contrast the smart
house would be able to communicate with the home owner in which the owner
could then decide to call the Police or to turn the alarm system off due to it being
a family member accidentally setting it off. To recap, the smart house would
make the security system more efficient by communicating its status to the home
owner, this would provide the home owner the ability to know that his house is
secure weather the owner is working or taking a long vacation trip.

Subsection 3.3.a – Similar Smart House Security
The Sensaphone Web600 Web-Based Monitoring and Alarm Notification System
priced at $355.50 is a really good example of Smart Security System. This device
allows the user to view live status images and recorder images all accessible
from anywhere in the world though the internet. This smart house device is able
to send text messages and email if one of the sensor value goes off range. What
this means is that any sensor that goes past a certain value will trigger the
system. An example could be if the smoke sensor is set off, this would cause the
system to notify the owner that the sensor has been set off. The system uses an

                                                                                 38
Ethernet connection in order to allow user to connect to its built in web-server.
The sensors that the system could include are temperature, smoke, doors,
windows and motion. All of the sensor would have to be bought separate from
the main unit which would drive up the cost of the system significantly. An
example would be the Sensaphone WSR-0105 Wireless Motion Sensor which
cost $175.49.

An interesting Smart Home security system is the Logitech Alert™ 750i Master
System. The system provides one HD camera which can be view through a
smartphone or via a computer using the internet. The way that the system sends
the live feed over the internet is what makes this system distinct. Instead of
sending the images wirelessly or through a long cable, it actually uses the power
lines to transmit the data. The technology that’s being used is called HomePlug
which offers very high-bit rate over the power line. The system works by
receiving the images from the power line where a special Internet Hub converts
those signal and sends them over Ethernet so that it can connect online. The
system also features motion detection and a microphone to record. The Logitech
Alert™ 750i Master System cost $299.99.

One of the most expensive smart security systems can be found under ADT
Family Package. The professional installation cost $549.00 but the buyer has to
pay $46.99 a month for the system to be monitor by ADT. The system includes a
Touchpad Control panel, two windows/door sensors, a temperature or carbon
monoxide sensor, a PIR motion detector, siren, smoke/heat detector, a yard sign
and a Safewatch CellGuard Primary Unit which is used in case a phone land-line
is not available. The ADT Family System works by sending a signal to a person
working at ADT Customer Monitoring Center. The signal could be related to a fire
or due to an unauthorized entry. In case of a break in the ADT representative
would call the house to check if it was a false alarm. The representative would
ask for a password and if the incorrect password or phrase was given then they
preceded to call the fire or police department. Since the set-up of the system is
done professionally and very little knowledge on computer or maintenance is
needed this was once the most popular way to have a secure home. But due to
the exploding technologically incline people this system is not as popular as it
used to be. Another problem that this system experience is that the buyer will
have to continually pay monthly bills to keep the system running. Once the
customer stops paying the monthly bill, ADT un-install all of their equipment and
takes them back.

Subsection 3.3.b – Smart House Health Devices
Beside Home security Smart Houses are also being seen as an alternative way
to make the life of the elderly better. Many senior citizens are put into retirement
homes even though all they need is a little support. An example of a reason of
why a person would be put in a retirement home could be due to memory loss or
having Alzheimer. The degree of Alzheimer or memory loss varies from person to

                                                                                 39
person but if the memory loss is minimal then there could be simple solutions to
help the elderly life out their life as convenient as possible out. One example in
which were elderly suffer is when they forget to take their medication on time. By
forgetting to take their medication, the elderly person or their family are required
to take the action of going to a retirement home or to hire someone to take care
of them. Both of these solutions come at a very expensive price which is not
good for the elderly or his family. A simple solution would be to have the smart
house announced a reminder that they must take their medicine. A device that
has been made to remind people of when to perform a certain task is called The
Wellness Wizard which cost $149.00. The device works by playing recorded
messages from family members on when to do a certain task, such as take their
pills. If the person on the house does not push a button confirming that he/she
received the message, then the machine would call the phone contacts informing
them of this. One of the cons that this system has is that only users with mild
memory loss can learn how to use it.

Section 3.4 – Design Features being incorporated in the
Smart House Project
For the project the group had to pick which features to implement these features
were based on security, energy-efficiency or convenience. Since this is a Smart
Green House the group decided that energy efficiency was one of the main goals
needed to be implemented in the Smart Green House. Implementing the energy-
efficiency into the smart house means that different energy-efficient techniques
need to be applied into the project. A simple example would be the ability to turn
a device off when it’s not being used. The smart house could also use methods
such as automatic timers or measuring when the device is on standby mode to
cut off the power that is being wasted. Instead of just choosing to select one
method over the other the best solution would be to combine both of the methods
mention before. Combining both methods would allow for the best way to save
energy and be more flexible for the user. The next part of the project would be to
make the smart house easily accessible. By being able to easily access the
control of the smart house the user’s life would be much simpler since the user
would not have to struggle in order to alter the desire commands. There are
several ways in which the customer could be able to control the smart house.
The first would be to have a central control unit, there the user could input the
desire setting of the house such as how long until the lights turn off after he
leaves the room or the brightness of the light. Another way in which the user
could be able to control the house would be via the internet. The user could log in
from anywhere around the world and be able to control or check up on his house.
Incorporating these two features would make the experience of having a Smart
Green House a lot more convenient and will also allow the customer to monitor
the house and the power usage more effectively as well as other information
present within in the growing system of the project such as the water level in the
reservoir.


                                                                                 40
Section 3.5 – System Standard for communication
between devices
Subsection 3.5.a – X10
The X10 protocol was developed in 1978 by Pico Electronics, the protocol and
products were develop in order to control lights, or any other electrical product
which used the power line as its source for electricity. The X10 protocol works by
sending short Radio Frequency (RF) signal through the power line. The X10
sends a burst of 120 KHz at the zero crossing point of the AC power line. The
120 KHz signal must be sent three different times in order to coincide with the
three different phases of the power line. Since the transmitting speed depends on
the zero crossing point the maximum data that the X10 can accomplish is 60 bps
or 50 bps, depending on the country the device is being used in. The X10
represents the binary number 1 as a one-millisecond burst of the 120 KHz signal,
while the binary number 0 is the absence of the 120 KHz signal. The transmitted
code consists of eleven cycles which represent three different parts. They are the
Start code (2 cycles), House code (4 Cycles) and key code (5 cycle). The start
code is always sent as 1110. The House and Key code are sent complimentary
to the bit sent. So if a 1 is sent then a 0 should follow, this is a form of simple
error detection and allows the system to identify when an error occurs.

The X10 seem to be a pretty good choice for home automation but there are
many problems that can and do occur when using this protocol. The first problem
is encryption; this protocol offers no encryption at all so the devices running the
protocol could turn off/off accidentally. If a nearby neighbor uses the same
technology then some of the signals could get picked up and accidently perform
that task on the neighbor’s side. This would make the home owners have a great
deal of inconvenience since they are accidently or even purposefully turning
devices on/off. Another way that the system fails is that the signal from the X10
transmitter would never reach the receiver due to the home wiring absorbing the
signal. The farther the transmitter is set from the receiver then the weaker the
signal would get. This is also worsen by the fact that if the transmitter is not
connected to the same phase as the receiver, then the signal would have to go to
the breaker box and back to the receiver which means a much weaker signal.
There are also devices which absorb the signal; these include televisions,
computers and even other x10 transmitter which report their status back.

Subsection 3.5.b – Universal Powerline Bus
The Universal Powerline Bus (UPB) was developed in 1999 by Powerline Control
Systems (PCS). The UPB system also uses existing power lines to send a signal
which controls connected devices. The UPB system works by charging and
quickly discharging a capacitor. This causes a large spike across the power line
which is then picked up by receivers. The pulses are strong enough to travel the

                                                                                41
home wiring distances and even farther. The pulses are generated on specified
time of the power line since and are therefore classified as Pulse Position
Modulation (PPM). The values which the pulses can take are from 0 to 3 and the
pulses are generated every half cycle on an AC power line. The speed at which
the device can send data is 240 bps. There UPB incorporates many features
such as two way communication which allows the devices to report their status.
Another feature is that they can be program with the help of a computer and thus
set a secure link between controls by using a password. The USB also claimed
that the reliability of their product was 99% which is an essential feature of smart
houses. The drawback to this technology is that you need the device to be
connected to the power line so that it can receive the signal.

Subsection 3.5.c – ONE-NET
A new communication method that has come up is called One-Net it was
developed by a company called Threshold. The reason that this new protocol
was developer was for it to control wireless networking devices for home
automation. The goal of the protocol was to be secure, low cost, and to optimize
devices which used battery. A very good feature about the ONE-NET protocol is
that as it was being developed it became free and open source for anyone that
wanted to implement it. An advantage of this new protocol is that it can use many
different wireless transceivers and microcontrollers which allows for a bigger
range in design and is small in size. ONE-Net also claims that the wireless range
for the protocol has measure around 500 meter outdoor and 60-100 meters
indoor which is exceptionally good compare to other wireless protocol. The
different types of configuration witch ONE-NET supports are Peer-to-Peer (P2P),
Star or Mesh. The ONE-NET also uses default encryption of XTEA2. Having an
encryption is critical in having a wireless home automation since it is so easy to
tap into the system and change different settings which would cause headaches
for the house owner. Another good feature of the One-Net is its data rate which
ranges from 38.4 to 230 Kbps this is significantly more than power line data
transmissions which raw data range from 50 to 240 bps.

Subsection 3.5.d – Z-wave
The Z-Wave is another form of home automation standard that was developed by
Zensys. The Z-Wave operates in the 850 to 950 MHz radio frequency range. The
developers choose to operate the Z-Wave in those frequencies instead of the
conventional 2.4 GHz band for two main reasons. The first is that operating at the
900 MHz range allows lower power usage since the physical propagation range
is around 2.5 times the equivalent of the 2.4 GHz signal. The second reason why
the 900 MHz range was chosen instead of the 2.4 GHz band is that there is a lot
of interferences in that band due to Wi-Fi and wireless phones. The Z-Wave
protocol is a mesh network and the data transfer speed is 9600 bps. To install
devices over the network the device being install must first be program in closed
proximity to the control unit. The control unit will assign a specific home code to

                                                                                 42
the device which then can be control via the control unit. This feature is included
in the Z-wave protocol so that the system would be secure and other Z-Wave
control units do not accidentally control other Z-wave products which are not
meant to be on the network. The Z-wave is only sold as a system in a single chip.
This system includes a microcontroller with the Z-wave protocol and the
transmitter. The Z-wave claims the following in their microchip system:

Z-Wave Features for their microchips:

• Z-WaveAV single chips are fast & easy to integrate into advanced AV products
  – Rich set of peripherals specialized for AV control enables true single chip
      remotes
   – Easy AV device integration thanks to full speed USB 2.0 and multiple serial
      ports
   – Configurable Z-WaveAV reference applications for rapid product integration
      Eliminate need for costly firmware development projects for most devices
• Efficient protocol design
   – Over 100x better WLAN interferer blocking than competing RF chip sets
   – Multi-channel support with concurrent listening eliminates packet loss
• Excellent in-door range even in challenging environments
    – Typically 20-30m indoor in non-line-of-sight setup
    – Over 10m non line-of-sight range even with strong WLAN interferers active
• Efficient protocol design
    – 100 and 200 kbit/s operation with minimal overhead
    – Full compatibility to Z-Wave mesh networking in home control
• Lowest power consumption
    – Multi-year battery life on only 2 AAA batteries

Subsection 3.5.e – DASH7
Another new technology that has emerged is the DASH7; this technology uses
the ISO/IEC 18000-7 which is needed for active Radio Frequency identification
(RFID) devices. The frequency that the DASH7 technology operates is at 433
MHz the benefits of using these frequency is that is not as high power as the 2.4
GHz frequency which lowers power usage, this frequency is not as crowed and is
able to travel and penetrated concrete which other higher frequency can’t do
without data loss. DASH7 offers a free open source code written in C in order to
implement the protocol on microchips, the software is called OpenTag. The
protocol already has major chip companies such as Texas Instrument,
STMicroelectronics and Semtech which offer microcontrollers and development
kits that are compatible with DASH7 protocol. The only downfall in this
technology is that since it’s so new there is very little documentation on the
internet about how to incorporate the protocol into the project. Other-wise this
protocol would have been excellent to use since it has many good qualities.
Below are the specifications which the DASH7 features:


                                                                                43
DASH7 Features:

      Range: Dynamically adjustable from 10 meters to 10 kilometers
      Power: <1 milliwatt power draw
      Data Rate: dynamically adjustable from 28kbps to 200kbps.
      Frequency: 433.92 MHz (available worldwide)
      Signal Propagation: Penetrates Walls, Concrete, Water
      Real-Time Locating Precision: within 4 meters
      Latency: Configurable, but worst case is less than two seconds
      P2P Messaging: Yes
      IPv6 Support: Yes
      Security: 128-bit AES, public key
      Application Profiles: None

Section 3.6 – Microcontroller
Subsection 3.6.a – Selection of Microcontroller
The selection of the microcontroller is a very important part of designing the
project since it will determine several part of the project such as the power
supply and the language in which it can be program. The first requirement that
the microcontroller needs to have is that it needs to be inexpensive to buy and to
program. The microcontroller needs to be low-priced in order to keep the Smart
Green House project affordable. The microcontroller also needs to be simple to
program since every device that is going to be develop will be interface with the
microcontroller in order to perform its task, which could range from turning a
relay switch on/off to measuring the amount of current and storing the data for
later use.

The second requirement that the microcontroller needs to have is that it needs to
be as power efficient as possible, without sacrificing reliability. Since one of the
Smart Green House objectives is to reduce the amount of wasted power, it
makes sense that the microcontroller and other components need to be able to
work using low amount of power. By choosing a low power microcontroller and
related components the team is also able to have the flexibility of designing
devices that operate with batteries and those devices would have the benefit of
having a longer battery life. The next feature that the microcontroller needs is
based on the development kit which bring all the require software and hardware
in order to program. The development kit also needs to be economical since
there are development kits which cost hundreds of dollars and that amount is not
acceptable in building the smart house components. The last requirement that
the microcontroller must have is to be compatible with the required transmission
protocol because there is a need to have enough space and be fast enough in
order to incorporate the wireless protocol into the smart greenhouse system.



                                                                                 44
Subsection 3.6.b – Arduino Duemilanove ATMega 168
Microcontroller
The Arduino is a prototyping platform which allows to program microcontroller
easily via the use of a computer through its USB port. The microcontroller in the
Arduino is program with an IDE that incorporates Wiring/Processing language
which uses simple commands to read/write to its I/O ports. The Arduino
Duemilanove consists of the Microcontroller, LED’s, USB connection and cost
around $30.00. The microcontroller is a 16KB AVR 8-Bit Microcontroller with a lot
of features that are required for the project such as having A/C converters,
Oscillators and power saving modes.

Peripheral Features

   One 16-bit Timer/Counter with Separate Prescaler, Compare Mode, and
    Capture Mode
   Real Time Counter with Separate Oscillator
   Six PWM Channels
   8-channel 10-bit ADC in TQFP and QFN/MLF package
   6-channel 10-bit ADC in PDIP Package
   On-chip Analog Comparator
   Power-on Reset and Programmable Brown-out Detection
   Internal Calibrated Oscillator
   Five Sleep Modes: Idle, ADC Noise Reduction, Power-save, Power-down,
    and Standby
     I/O and Packages
   23 Programmable I/O Lines
   28-pin PDIP, 32-lead TQFP, 28-pad QFN/MLF and 32-pad QFN/MLF
    Operating Voltage:
   2.7V - 5.5V for ATmega48/88/168
    Low Power Consumption
   Active Mode: (250 µA at 1 MHz, 1.8V) (15 µA at 32 kHz, 1.8V (including
    Oscillator))
   Power-down Mode: 0.1 µA at 1.8V

Subsection 3.6.c – MSP430 Launchpad Value Line
Development Kit
This is another development platform which has all of the necessary equipment
to program and debug microchips which are develop by Texas Instruments and
start with MSP430. The development kit which brings two MSP430
microcontroller and cost $4.30 is pretty inexpensive and would be a great kit to
use for the project. The MSP430 microcontroller is a 16-Bit microcontroller which
is design to operate using low power.

                                                                              45
Features that the microcontroller includes are:

    Low Supply-Voltage Range: 1.8 V to 3.6 V
    Ultra-Low Power Consumption
     – Active Mode: 220 µA at 1 MHz, 2.2 V
     – Standby Mode: 0.5 µA
     – Off Mode (RAM Retention): 0.1 µA
    Five Power-Saving Modes
    Ultra-Fast Wake-Up From Standby Mode in Less Than 1 µs
    16-Bit RISC Architecture, 62.5-ns Instruction Cycle Time
    Basic Clock Module Configurations
     – Internal Frequencies up to 16 MHz With One Calibrated Frequency
     – Internal Very Low Power Low-Frequency (LF) Oscillator
     – 32-kHz Crystal
    External Digital Clock Source
    16-Bit Timer_A With Two Capture/Compare Registers
    Universal Serial Interface (USI) Supporting SPI and I2C
    Brownout Detector
    10-Bit 200-ksps A/D Converter With Internal Reference, Sample-and-Hold,
     and Autoscan
    Serial Onboard Programming, No External Programming Voltage Needed,
     Programmable Code Protection by Security Fuse
    Available in 14-Pin Plastic Small-Outline Thin Package (TSSOP), 14-Pin
     Plastic Dual Inline Package (PDIP), and 16-Pin QFN

Subsection 3.6.d – rfPIC with Transmitter
The rfPIC12f675K is a microcontroller which also incorporates a transmitter in
the same packaging. The Radio Frequency transmitter works under the 290 MHz
- 350 MHz frequency and the voltage levels needed to operates range from 2V-
5.5V. There are many benefits of having a transmitter in the same packaging as
the microcontroller. The first example is that it would eliminate the space require
to implement the design on the PCB since it’s already take care of. Another
benefit is that it would lower the cost of the design since the transmitter is not
needed to be bought separately. The last benefit that comes from incorporating
the transmitter is that it minimizes the potential of errors due to incompatible
designs for specific Microcontrollers. The cost of the unit is $2.11. Some of the
features that the PIC includes are:

rfPIC Transmitter Features:

   128 bytes of EEPROM Data Memory
   Programmable pull-up resistors
   ICD support
   4 oscillator selections including 4 MHz RC oscillator with

                                                                                46
   programmable calibration and Power-on Reset
 up to 10dBm transmit output power
 Up to 40kbps data rate.

The benefits of microchips which incorporate transmitter, ADC or sensors that
monitor current and voltages are ideal to this project. The reason that a
transmitter incorporated with the microchip is good is because it helps the design
part of the project by making sure that the microchip is compatible with the
transmitter. The incorporation of the transmitter also helps the design part of the
project because the company that produce the part will also provide code which
will help program the microchip in junction with the transmitter. Besides having
transmitter there are also other microchips which are specifically design to
measure voltages and currents. Since measurement of current and voltages is a
main part of the project it is wise to see what the advantages of a microchip
focuses on measurement of current and voltages.

Subsection 3.6.e – MSP430AFE42xx Microcontroller
The MSP430AFE42XX is a microchip Made by Texas Instruments focusing on
single-phase metrology. The microchip allows application such as, home
automation, electric meters, sub-metering and energy saving systems. The
microchip series is based on a 16-bit architecture running at a frequency of
12MHz. The measurements of the microcontroller reach less than .1 percent
error which is a good feature for the project since it is above the desire
percentage error for the specs. The microcontroller also has many different
communication lines which is also a requirement for the project. Figure 3.3 show
that by integrating the components on the microchip it reduces the system
components of a ratio of four to one.




      Figure 3.3: Microcontroller Integrated Components Before and After Diagram
                          (Courtesy of Texas Instruments [7])



                                                                                   47
The features that the microchip has are:

   Low Supply-Voltage Range, 2.7 V to 3.6 V
   Ultra-Low-Power Consumption:
   Active Mode: 400 µA at 1 MHz, 3.0 V
   Standby Mode: 1.6 µA
   Off Mode (RAM Retention): 0.1 µA
   Five Power-Saving Modes
   Wake-Up From Standby Mode in Less Than 6 µs
   Frequency-Locked Loop, FLL+
   16-Bit RISC Architecture, 125-ns Instruction Cycle Time
   Embedded Signal Processing for Single-Phase Energy Metering With
    Integrated Analog Front-End and Temperature Sensor (ESP430CE1B)
   16-Bit Timer_A With Three Capture/Compare Registers
   Integrated LCD Driver for 128 Segments
   Serial Communication Interface (USART), Asynchronous UART, or
    Synchronous SPI Selectable by Software
   Brownout Detector
   Supply Voltage Supervisor/Monitor With Programmable Level Detection
   Serial Onboard Programming, No External Programming Voltage Needed,
    Programmable Code Protection by Security Fuse
   Bootstrap Loader in Flash Devices

Subsection 3.6.f – CC430 RF Microcontroller
The CC430 RF Microcontroller is similar to the Texas Instrument
MSP430AFE2xx. The main difference is that the CC430 was design to facilitate
communication using Radio Frequency in the sub 1 GHZ rate. The microchip is
also 16 bit and it can operate with a voltage range from 1.8V to 3.6V. The chip
brings in a built in transceiver which allows it to send and receive data. The
benefit of this microcontroller is that it will lower the parts needed to build
communication between the different devices that are going to be added.

Features for the CC430 RF Microcontroller:

   True System-on-Chip (SoC) for Low-Power Wireless Communication
    Applications
   Wide Supply Voltage Range: 1.8 V to 3.6 V
   Ultra-Low Power Consumption:
   CPU Active Mode (AM): 160 µA/MHz
   Standby Mode (LPM3 RTC Mode):2.0 µA
   Off Mode (LPM4 RAM Retention): 1.0 µA
   Radio in RX: 15 mA, 250 kbps, 915 MHz
   MSP430™ System and Peripherals
   16-Bit RISC Architecture, Extended Memory, up to 20-MHz System Clock

                                                                            48
   Wake-Up From Standby Mode in Less Than 6 µs
   Flexible Power Management System with SVS and Brownout
   Unified Clock System with FLL
   16-Bit Timer TA0, Timer_A with Five Capture/Compare Registers
   16-Bit Timer TA1, Timer_A with Three Capture/Compare Registers
   Hardware Real-Time Clock
   Two Universal Serial Communication Interfaces
   USCI_A0 supporting UART, IrDA, SPI
   USCI_B0 supporting I2C, SPI

Selecting the microcontroller is a pretty hard choice since there are so many
different types which can be chosen. The selection of the microcontroller
primarily came down to Texas Instruments MSP430AFE2xx and the CC430 RF.
Since both of the microcontrollers are from the MSP430 series, they pretty much
have the same features such as voltage range, current drawn, communication
interfaces methods and memory sizes. The reason that those two
microcontrollers were chosen as the final two microcontrollers is because they
each provide a feature which is necessary for the project. The MSP430AFE2xx
main benefit is that it focuses on measuring power, while the CC430 RF primary
focus is being able to communicate with other devices using radio frequencies.
Since the smart house project has two goals, one which is to measure power of
an appliance and the other one is to simply turn lights on and off. It is best to
select both microcontrollers and test which one would be more appropriated for
the design of the project. The last reason why they were chosen was because
their development kit to program and test the microcontroller only cost $4.30.

Section 3.7 – Specifications for the Wall Unit
The use of a wall unit which would allow control of other electronic device was
decided in the project because it can be used as a timer or a current sensor to
detect devices which go onto standby mode. Since the device that will be
incorporated is going to be in between the electrical outlet and the load needed
for the device to be able to connect to the socket and be able to maintain its
weight without falling off. For the unit to work a male AC plug to connect directly
to the electrical outlet is needed. Two sockets will be included in the unit one will
be connected directly to the electrical outlet and always be on while the other one
will be control by different elements.

The second outlet will be control using a microcontroller which enables a relay
switch or a Triac. By using a relay switch or Triac the current can easily be
control to on, off or even just lowered, this will allow the person using the wall unit
the flexibility of adjusting the brightness settings on a light if so desired. The relay
switch will be included to completely open up the circuit when required. While the
Triac will be included to control the amount of current that passes through the
load.

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Another important feature of the device is the dimension that is going to occupy.
The dimension of an AC outlet cover found in homes has a length of 4.5 inches
and a width of 2.5 inches. For the device to be easy of the eyes the dimension of
it will need to be as close as possible as a standard AC outlet. Another
specification that is extremely important is the amount of power that the device
will be able to safely handle. The maximum amount of power that the instrument
needs to measure does not have to exceed 1800 watts since by then the fuse
install in the house will have been set off. The wall unit will also need to be able
to measure the voltage and the current on both sockets and store the data on its
memory until the main unit requests the data. The unit will also need to be able to
communicate to the main unit located ninety feet away wirelessly.

Specs and components for the wall unit:

   Weight less than 1lb
   Dimension less then: L- 6" W- 3" D-2.5 "
   Max Current 15A
   Max Power 1800W
   Communication Range at least 90ft
   Power Measurement accuracy of +- 2%
   1 AC Male Plug to derive power
   2 AC Female Sockets in order to connect 2 loads
   1 Reset button to erase all measurements and configuration
   1 Microcontroller for control of unit
   1 transceiver in order to send/receive data
   1 Potential sensor for voltage measurement
   1 Current sensor for current measurement
   Operate temperature range from -25 c to 85 c
   Wall unit should be enclosed in plastic frame

The Block Diagram for the wall Unit will consist of 5 different blocks. They are the
power supply, control unit, sensors, load control and communication. In the
power supply there is going to incorporate the step down transformer and the
voltage regulator. The control unit will be a microcontroller which will retain the
measurements and execute commands. The next block is the sensors, included
in this block will be a potential and current transformer which will measure their
values and send them to the microcontroller. The load control block will have a
relay switch and a thyristor to control the amount of current that the load can
receive. The last block is the communication one; this block will have a
transceiver capable of transmitting and receiving RF signals. Figure 3.4 shows
the block diagram for the wall unit:




                                                                                 50
             AC


                                                                          AC
         Power Supply


                                                                      Load Control




                                     MCU                    Sensors


        Communication
                                                                          Load




                        Figure 3.4: Block Diagram of Wall Unit


Subsection 3.7.a – Power Supply Design

The power supply is necessary to turn the 120V RMS into a manageable DC
Voltage which the microcontroller and other components can operate. The power
supply should be as small as possible in order to fit into the casing but still be
able safely handle the current supply for the components but it does not have to
provide any current to the load since the load is going to be operating of the
outlet voltage. The power supply should have these features:

Power Supply Features:

   Safely handle at least 300mA
   Output Voltage 2.5V
   Ripple Voltage less than 100mV
   Current Loss less than 30mA
   Efficiency of transformer greater than 80%

In order to bring down the voltage to a level where the voltage regulator can
operate, a transformer with the appropriate turn ratio is needed. The turn ratio
that the transformer needs to be is 12:1 this turn ratio will lower the 120V RMS to

                                                                                     51
12VRMS. The transformer must also have a voltage rating that is higher than
125VRMS so that arcing across the insulators won’t occur. Another parameter
needed for the selection of the step down transformer is the current rating. The
current rating is important in order to maintain the temperatures in the
transformer cold enough. If the current rating is exceeded there is a risk in which
the insulator around the winding could melt and create a short.

Once the voltage passes through the transformer, it will then pass through a full
wave rectifier which will change the alternating voltage into direct voltage. Due to
voltage drop from the diode there is a voltage drop of around 1.5V, this places
the voltage at around 10.5VRMS. In order to filter out the ripple a VLO is place
next. The voltage regulator will further step down the voltage to the desired 2.5V
and maintain it at that level. The LM317 was selected from Texas instrument in
as the voltage regulator. The reason that this voltage regulator was chosen is
because is very few extra part are required in setting the voltage.

Features of the LM317 Linear Voltage Regulator:

   Output Range 1.25V- 37V
   Output Current up to 1.5A
   Internal Short-Circuit Current Limiting
   Thermal Overload Protection
   Output Safe-Area Compensation

In order to calculate the desired voltage the following equation was use:




Since IADJ is usually in the range of 50UA it can be ignored for the calculating the
desired voltage. VREF is set at 1.25V with a ±4% error. Setting R2 and R1 equal
to each other will provide the desired Voltage of 2.5V for the output. To fine tune
this voltage a variable resistor connected in series with R2 will be added. The
power supply will be tested with different loads for a set amount of time in order
to make sure that it does not overheat and that it’s capable of providing steady
voltage at different loads. The LM317 is said to produce an output noise of .003%
of the output voltage. Since the output voltage is going to be 2.5V the output
noise will have a ripple of 7.4mV. Since that is without a load capacitors will be
placed on the input and output to further lower the ripple on the output of the
power supply.

Subsection 3.7.b – Load Control Parameters, Research,
and Design
The purpose of the load control is for it to control the amount of current that goes
through the load. This would mean that the load control must be able to handle at

                                                                                 52
least 20A and 120VAC. The original idea was to use a combination of a switch
relay and a Triac both of with would be capable those currents and voltage
ratings. The relay switch would have been a Single-Pole-Double-Throw switch
witch would have connected the load directly to the power line. The other side
would have a Triac connected in series with the load. Either side of the load
could have been selected by applying current to its field winding. Researching
the different relay switch the minimum voltage required to energize the winding
was 5V. This would make the design more complicated and expensive since
another voltage regulator would be need in order to acquire that specific voltage
level. Removing the relay switch will have many benefits and remove redundancy
in which the Triac element can perform. A benefit of not implementing the relay
switch is lower amount of components lowering the weight of the unit and a lower
cost for parts and PCB layout. The last benefit of removing the relay switch is
less power loss from powering the winding which typically range 100mA to
200mA.

Selection of the Triac to have all the necessary ratings proved to be difficult and
a long process. The first rating that the Triac need to have at least 20A current
that could go through it. The second rating the Triac needed to have is the
voltage rating of at least 125VRMS. The gate current and gate voltage for the Triac
to turn on also need to be as low as possible so that the power supply could
provide enough power to turn the Triac on/off. By having the microcontroller send
the pulse signal to be Triac would allow the controlling state of the load the, since
the Triac and the load will be connected in series with each other. There are two
different ways in which to control the amount of current that the passes to the
load. The first way is to control the duty cycle of load. This is done by turning the
Triac on for a certain amount of time and then turning it off for the remainder of
the time. The second way which current can be control via the Triac is by
controlling the firing angle in for every half cycle. By sending a trigger pulse to the
gate at a later angle would decrease the amount of voltage that goes through
since the Triac would not start conducting until the signal to the gate is receive
this would also result in lower current for the load. Figure 3.5 shows how the
Triac would control the voltage due to an offset in the trigger angle.




                Figure 3.5: Triac Output Waveform base on Firing Angle
                                (Permission Pending [8])

                                                                                    53
The percentage output power can be calculated from the firing angle using the
formula below:




Where:

I is the rms load current in amperes
Ip is the peak current in amperes
   is the firing angle in degrees
By using the above formula the firing angle can be calculated necessary in order
to acquire the desired output power to the load. Figure 3.6 shows the relationship
between the firing angles for the Triac gate versus percentage power deliver to
the load.


                          Firing Angle         Percentage Power
                               0                      100%

                              66                       75%
                              90                       50%
                              114                      25%
                              180                      0%

                   Figure 3.6: Firing Angle Verses Percentage Power

Connecting the power Triac would be the ideal case but due to certain problems
which arise from switching the load off or on at different times it cannot be done.
An example which could damage the microcontroller could occur when the Triac
is driving inductive load and the firing angle is set along mid wave. This would
cause a generation of high voltages on the gate which in turn would damage the
microcontroller since it can’t safely handle those high voltages. In order to isolate
the microcontroller from the load an Opto-triac in combination with a transistor
will be implemented.

The Opto-triac works by sending an infrared signal to the gate of the Triac inside
the chip which will then turn on the gate for the power Triac. Using the Opto-triac
will separate the load from the microchip since they are not electrically connected
together. Figure 3.7 shows the circuit which will send the trigger signal from the
microcontroller to the power Triac through the Opto-triac.
                                                                                  54
                             Figure 3.7: Triggering Circuit

The last component that will be needed in order to control the firing angle and
thus the power output to the load is a zero-crossing point sensor. This sensor will
measure every time when the line value of reaches 0V and send a signal to the
microcontroller where it will set the angle of the line at 0 The zero-crossing point
will allow the microcontroller to know the right amount of time needed in order to
send the firing signal to the Triac gate. In selecting the zero-crossing point circuit
to implement in the unit, there were two important factors to consider. The first
aspect that was looked in circuits that detect the zero-cross point was if the
circuit could work with a supply voltage off 2.5V.

Many of the circuits which included voltage comparators failed in meeting this
condition since they operate at around 5V. The next feature that was look at in
the selection was the complexity of the circuit. The less part required for the
circuit the better since it would be more cost effective in building the unit. The
circuit seen in Figure 3.8 is the circuit which seems to match all of the
requirements in order to implement the zero-crossing point sensor.




                                                                                   55
                    Figure 3.8: Original Zero-Crossing Point Circuit


The way that the zero-crossing circuit works is by taking the output of the rectifier
and passing that signal through a diode. The diode is connected in series with
two resistors which then goes to the base of the transistor. The transistor is set
up so that when it’s saturate the output will be grounded and the transistor turns
off the output would go high. The output would be connected to the
microcontroller which would receive a high signal whenever the voltage the zero-
crossing point. The purpose of the diode is to cut off the current to the transistor
when the voltage of the rectified signal reaches less than .7V. Instead of using
this circuit, the idea of this circuit will be taken in order to design a similar zero-
crossing point circuit.

A p-channel Depletion MOS Field-Effect transistor will be used instead of the BJT
transistor and diode in order to detect when the zero point is reach. The P-
channel depletion will only conduct when the applied voltage is 0V. In order to
protect the diode from voltage spikes a back to back diode will be placed
between the gate and the source of the transistor. If the potential difference on
the gate compare to the source is high enough around +-10V or static electricity
is encounter, the top diode will work in the forward direction while the bottom
diode will break down and work in the reverse direction so that the diodes can
provide a shunt path for the excessive charges. This protection for the gate is
called “Integral gate protection” and can come included in some MOSFET’s.


                                                                                    56
Figure 3.9 shows how the zero-crossing point detector is going to be
implemented in the wall unit. Figure 3.10 shows the simulation for the circuit.




                       Figure 3.9: Zero-Crossing Point Circuit




              Figure 3.10: Simulation for the Zero-Crossing Point Circuit

                                                                            57
Subsection 3.7.c – Sensors Specifications and Control
Parameters
The sensors for the wall unit must be able to measure voltage and current with a
percentage error of +-2%. The current sensor must be able to measure
alternating current ranging from 0A to 20A and send the information back to the
microcontroller as a voltage. There are many different methods in which to
measure current. For the wall unit the best possible match would be to use the
smallest and most cost effective equipment as possible. The first type of current
sensor that was research was a current transformer. The Current transformer
works by using induction to lower the current levels to levels that A/D converters
can safely handle. Since the current transformer use induction in order to bring
down the current to safe levels the wired carrying the current must be enclosed
by the current transformer. Current transformers can also send the current
measurements as voltages. The current transformer output would be rated in
volts per primary ampere this way would allow the designer to calculate the
amount of current base on measuring small voltages. The disadvantage of using
Current Transformers witch output voltage as measurement is that the signals
that are produce are low in energy, interference and signal degradation could
change the results of the measurements.

The next type of sensor to measure current that was look at was the shunt
resistor current sensor. The way that this current sensor works is by putting a
resistor in series across the load and measuring the voltage drop across that
resistor. There are two different techniques in which to use a shunt resistor to
measure the current, they are low side current sensing and high side current
sensing. Low side current sensing works by placing the current sensor between
the load and the ground. The benefit of using this method is that it’s simple,
inexpensive and accurate. It also only needs an op-amp in order to work. The
high side current sensing is placed between the power supply and the load.
Using this approach would require differential amplifier and make the circuit more
complicate. The advantage to using a high side current sensor is that it’s
connected directly to the power source. The disadvantage in using this is that it
required pretty accurate resistor matching since common-mode rejection ration
(CMMR) is greatly affected by the resistors.

The next technology that was look at to measure current was the Hall-effect.
Hall-effect equipment operates by measuring the intensity of the magnetic field
that’s in the wire cause by the current flow through the load. The higher the
current will create a higher magnetic field and the same logic applies to a lower
current through the wire. The strength of the magnetic field produce an induce
voltage on the equipment which can be directly related to the current. The
voltage that is induced in the equipment can be interface directly to an A/D
converter of to the microcontroller. One of benefit of using the hall-effect is that it
can measure the current without having to have an electrical connection between
the current and the sensor. Hall-effect current sensors are also able to measure

                                                                                    58
direct currents and alternation currents. Unlike the current transformer which
cannot measure DC current. Another benefit in using the hall-effect sensor is that
it is pretty small and light weight compare to a current transformer. The benefits
of implanting the Hall-effect sensor over the other type of sensor seem to be the
best possible solution for measuring current that passes though the load.

The Hall-effect current sensor selected to measure the one of the load is the
ACS756, this hall-effect is capable of handling 3kVRMS Isolation which is sufficient
greater than the 120VRMS required. The ACS756 hall-effect has many more
benefits as seen below.

Features and Benefits of the ACS756 Hall-Effect Current Sensors:

   Industry-leading noise performance through proprietary amplifier and filter
    design techniques
   Total output error 0.8% at TA= 25°C
   Small package size, with easy mounting capability
   Monolithic Hall IC for high reliability
   Ultra-low power loss: 130 µΩ internal conductor resistance
   3 kVRMS minimum isolation voltage from pins 1-3 to pins 4-5
   3.0 to 5.0 V, single supply operation
   3 μs output rise time in response to step input current
   20 or 40 mV/A output sensitivity
   Output voltage proportional to AC or DC currents
   Factory-trimmed for accuracy
   Extremely stable output offset voltage
   Nearly zero magnetic hysteresis

Since the microcontroller that was chosen for the wall unit focus on measuring
the current and the voltage, a diagram and a list must naming the Input-Output
(I/O) pins must be used in order to be able to implement the different
components required to measure the voltage and current.

Subsection 3.7.c – RF Communication
In order to communicate with other devices wirelessly a transceiver had to be
chosen. The transceiver had to meet several conditions in order to be included in
the wall unit. The first requirement that the transceiver need to pass was that it
could work with a 3V power supply voltage. This is essential since that is the
voltage that is going to be used for all of the components. The next condition that
the transceiver needs to have is to be compatible with the microcontroller; this
would allow the software and hardware to work without conflict. The last feature
that the transmitter required is that it could operate in sub-gigahertz frequencies.
Working in the Sub-GHz frequency would allow the signal to penetrate concrete
walls much easier than higher frequencies. The transceiver that was chosen for


                                                                                  59
the project is Texas Instruments CC1101 low power Sub-1GHz RF Transceiver,
the Features for this transceiver are seen below.

Feature for the C1101 Low power RF Transceiver:

   High sensitivity
   116 dBm at 0.6 kBaud, 433 MHz, 1% packet error rate
   112 dBm at 1.2 kBaud, 868 MHz, 1% packet error rate
   Low current consumption (14.7 mA in RX, 1.2 kBaud, 868 MHz)
   Programmable output power up to +12 dBm for all supported frequencies
   Excellent receiver selectivity and blocking performance
   Programmable data rate from 0.6 to 600 kbps
   Frequency bands: 300-348 MHz, 387-464 MHz and 779-928 MHz
   Analog Features
   2-FSK, 4-FSK, GFSK, and MSK supported as well as OOK
    and flexible ASK shaping
   Suitable for frequency hopping systems due to a fast
    settling frequency synthesizer; 75 µs settling time
   Automatic Frequency Compensation (AFC) can be used to align the
    frequency
    synthesizer to the received signal centre frequency
   Integrated analog temperature sensor
   Digital Features
   Flexible support for packet oriented systems; On-chip support for sync word
    detection, address check, flexible packet length, and automatic CRC handling
   Efficient SPI interface; All registers can be programmed with one "burst"
    transfer
   Digital RSSI output
   Programmable channel filter bandwidth
   Programmable Carrier Sense (CS) indicator

Section 3.8 – Testing Conditions and Procedures
for the Wall Unit
In order to confirm that wall unit as a whole will perform correctly, each individual
component will be tested separately. The test for each component will be
different since the components being tested have different operations. Most of
the test will required an oscilloscope and a wave generator in order to
accomplish the tests. While other test will use simple elements such as an LED
to demonstrate that the part is working correctly.

The first part that is going to be tested for the wall unit is the transformer. The
transformer will be tested on various conditions to ensure that it works properly.
The transformer will be tested on the amount of power that it can provide for the

                                                                                  60
load. Different loads will be placed and the temperature of the transformer will be
measure after an hour of operation. The temperature does not have to be
measure with a temperature device, it can simply be sensed by touch and
reported as cold, warm, hot and extremely hot. Since the transformer is
connected to the power line it must first be disconnected before performing the
test. Figure 3.11 shows the Transformer table to be filled in while testing.

        Transformer Test           Current            Temperature

                                   100mA
                                   300mA

                                   400mA
                                   500mA

                          Figure 3.11: Transformer Test Table

The second test that is going to be done is similar to the transformer but will be
perform on the voltage regulator. The test will measure the temperature of the
linear voltage regulator while is supplying different loads. The loads will once
again be change after an hour and the voltage on the output will be measure by
the oscilloscope. Then voltage on the regulator should always be constant at 3V
since that is the value that it was design to be. The ripple of the voltage regulator
will also be measure and documented during the test. Figure 3.12 shows the
voltage regulator test table to be filled in while testing.

     Voltage            Current        Temperature        Voltage    Voltage Ripple
  Regulator Test
                        100mA

                        300mA

                        400mA

                        500mA



                       Figure 3.12: Voltage Regulator Test Table

The next part that is going to be tested is the zero-crossing point detector. The
setup for this test will consist of hocking the gate to a signal generator. The signal
generator will have an output of 3V sinusoidal waveform running at 60Hz. The

                                                                                   61
voltage output of the transistor will be measure by the oscilloscope which will
show if the zero-crossing circuit is firing when the voltage level reaches close to
zero volts. The sinusoidal input and the transistor output will be overlap in the
oscilloscope and the time difference between the zero-crossing point circuit and
the actual 0V will be recorded and use for the load control circuit. Figure 3.13
shows the Zero-Crossing Point circuit table to be filled in while testing.

                       Zero-Crossing          Time Difference
                      Point Circuit Test           (ms)




                      Figure 3.13: Zero-Crossing Point Test Table

To test the Triac a sinusoidal signal of magnitude 12V will pass through the load
and the Triac. The Triac will be set to turn on at different firing angles and the
output voltage will be measure with the oscilloscope. The Triac should turn on at
the desire firing angle if it does not then it means that the test did not work. The
microcontroller will be the system that determines the firing signal and is going to
be mixed in with the zero-cross point circuit. If the Triac turns on close enough to
the firing angle then the error measurement will be calculate and recorded. If the
percent error is less than 2 percent then the Triac can be set to pass otherwise
the Triac will be set as fail. Figure 3.14 shows the Triac Test table to be filled in
while testing.

                Triac Test    Firing Angle       Error %       Pass/Fail
                                  Set at
                                   0

                                   30

                                   90

                                  120

                                  145

                                  160


                             Figure 3.14: Triac Test Table



                                                                                  62
The last part to be tested is going to be the communication transceiver. To test
the RF transceiver, two different microcontrollers will be set up to communicate
with each other. One microcontroller will transmit a code in order to turn on a
certain LED. The other microcontroller will receive this information and perform
the requested operation. After every successful test the two microcontrollers and
transceivers will be separate by 15 feet until the test reaches the 90 feet
requirement. The receive signal strength will also be recorded in the table in unit
of dBm (dB-miliwatt). As long as the receiving microcontroller is able to perform
the requested action the result will be label as pass or fail. Figure 3.15 shows the
Communication Test table to be filled in while testing.

        Communication       Distance       Signal       Pass/Fail
           Test                           Strength
                              15ft

                              30ft

                              45ft

                              60ft

                              75ft

                              90ft


                       Figure 3.15: Communication Test Table


Subsection 3.9 – Conclusion on Wall Unit
Design
In summary, the design of the control unit involved many different characteristics
in order to accomplish the final design. The characteristics involved in designing
the wall unit were research, previous knowledge and skill. Previous knowledge in
electrical engineering allowed the understanding of the different parts that were
required to successfully design the wall unit. Researching the different devices
that are used in smart house was the most time consuming aspect of the project,
but it showed the different routes that the group could have taken. While
performing research many ideas where taken and used for the wall unit. Another
part of research was during the selecting of parts. Many features were looked at
and the best possible match was selected based on price, performance and
compatibility. The last part in the design of the wall unit was the skill needed in
order to put all the different parts together to get the unit working as a whole.



                                                                                 63
Section 4 – Design & Research Related To
Central Control Unit
Section 4.1 – Hardware Research & Design For
Central Control Unit

Subsection 4.1.a – Introduction

The purpose of the interface design is to integrate the sensors from the
aeroponics system and sensors for the smart house. In addition, the integration
of the sensors to be smoothly connected to a computer that takes the data and
displays them on a website.

To begin with, the data from sensors is taken on a single input line where the
data sent over the wire is whether the device is on or not. Then the information is
routed via a mux to a dual signal splitter/copier that will send it to a LED display
and the other to a mux that will connect to a USB connecting to a computer. In
addition, the mux that connects to the USB is wired to buttons that allow for the
mux to switch direction of the wires taking information from the computer to the
initial mux connecting the sensors that will send data back to the sensors to turn
them on or off depending on the needs. A picture of the above depicted
schematic is given below.




                      Figure 4.1: Diagram of main circuit layout


                                                                                 64
Since the power supply is still required for all components to work properly, but
has different spec for the digital components; such as, the LEDs, computer and
muxes, its description will be included in the design and not in the summary. In
addition, the translator as depicted in the above picture is to convert from the
layout of the buttons to the 2n available connections of the mux.

The design of the 16 by 1 multiplexer was not involving since the part was
available in the market. The multiplexer has 4 bits for selecting between the 16
inputs and outputting on one line. The inputs of the multiplexer came from the
Read/Write selector switch that makes the decision between reading and writing
to the sensors coming from the smart house or aeroponics system. The purpose
of this multiplexer is to check where the sensor are on or off in. Thus keeping
accurate information about the system performance and creating an easy
method of troubleshooting if required. In addition, keeping track of this
information will prove to be useful when using a LED display to make correct
choices when using the button interface that will be discussed later in another
section. The part for this design operates at about 5V with a tolerance from 0V to
15V.

As mentioned the 16 bits of input come from the sensors where each sensor will
have exactly one line of input represented by the 16 bit line on the mux. The
sensors will be turned on or off by sending a high to the sensor to turn it on and
then sending another high to turn it off. Furthermore, the 4 bits of input into the
multiplexer that select between the 16 lines of input come from the control core,
that takes decisions from buttons chose by the user of from the computer chosen
by the user utilizing the program to make the choices.

Also, the same applies for the single bit output line coming from the multiplexer.
The single bit output line goes to the control core where the input from the
sensors is sent to the appropriate location. The specifics of the control core
design will be discussed in later parts of the report in greater detail.




                        Figure 4.2: Output from selector input


                                                                                65
                 Figure 4.2: Continuation of Output from selector input

The above table shows the 4 bit selector and which of the 16 input lines will be
available when the input on the selector is a certain value. Each individual input
line might not be utilized; however, it might be skipped or kept as a reserve for
later to for increasing the scale of the project to suit higher demand in managing
sensors. The part number for this specific design is MM74C150N-ND from the
Digi-Key website.

Moreover, the decoder that will be utilized for the project has 16 bits or wires of
output and in input wire with 4 bits/wires of selector which will traverse the 16 bits
of output. The purpose of the decoder is to write to the sensors. To clarify, the
decoder will receive a high from the control core and it will turn on a sensor by
sending a high to the sensor. On the other hand, to turn the sensor back off, the
multiplexer will communicate a high again to the sensor. This method requires
that the sensor has a switch that responds to this kind of input. Therefore, a
digital toggle switch is used to fulfill this design requirement. Below is the design
of the decoder that will serve the aforementioned purpose.

The 16 bit wires/ bus that goes to the sensors first passes through the
Read/Write selector that will make the decision to read or to write from the
control core. Furthermore, the 1 bit input line comes from the control core
similarly to the multiplexer. The four bit input selector to the decoder comes from
the control core that will make the decision of which sensor to read or write to.
The binary table showing how each selector corresponds to the output on the 16
bit line is very similar to the multiplexers except the direction of dataflow in this
case is opposite. Thus, it would be redundant to show the table again when the
similarities are so great.

The operation of the part required for this project is 0V to 15V tolerance with a
working medium of 5V. Since this is a digital design operation, the working
voltage is 5V. Powering the system will be discussed in later parts of the paper.
However, a single input to the wall socket will supply the power needed to the
design board for the entire central control unit connecting the various sensors to
the computer. The power supply will divide the voltage as required with the
current at the accepted levels for each component.

                                                                                   66
Next what follows is the description of the read/write selector switch. The
purpose of the switch is to go back and forth when chosen, between the decoder
and the multiplexer. Without this switching mechanism, the sensors would be
confused as to when they are to be turned on or off. Leading to a toggling
between on and off; as well as, creating difficulty in communication between the
decoder that takes information about the switches condition and passes it to the
control core. Therefore, the switching mechanism is very important to regulate
the read and write signal to the central control unit. The design of the switching
mechanism is very simple. There is a 16 bit output going to the sensors which
also serves as the input from the sensors. Two 16 bit lines, one serves as output
to the decoder while the other serves as the output from the multiplexer, are the
main bus lines connecting to the 16 bit sensors’ line. To control the switching
action between the two 16 bit lines, a single bit line coming from the control core
takes care of this requirement.

As shown, the Read/Write selector switch has a simple design. Inside the
switching mechanism there is an S-R flip flop with the reset input with an inverter.
The purpose of this design is to not allow the S-R to toggle between zero and
one. Therefore, there can only be a zero or a one assigned to either R or S but
not both at the same time. The output of the flip flop is sent to the power supply
of the multiplexer and decoder. Also, the input power of the two components is
differentiated by an inverter on the multiplexer. This method serves the purpose
of allowing only one of the components to turn on at a time. Due to collision of
information, and information becoming garbled as a result, the inverted design
was selected. When the multiplexer is on the decoder is not on, and vice versa is
correct.

The busses were fused in order to save space and take redundancy out of the
design. Since only one of the components will be turned on at a time, there is no
need to have two busses leading to the same location separately. Furthermore,
the power supply turning on the two components will be the same as there is one
load on the 5V supply at a time. The S-R flip flop will have its own power supply
coming from the power supply design described later on in the paper. Going into
the S-R flip flop is the one bit input from the control core that will chose which
action to be performed, the reading or writing. A low on the input line will turn on
the decoder and information will be sent to the appropriated selected sensor.
While a high on the input line of the flip flop will trigger a read and information will
flow to the multiplexer to be sent to the LED display and also onto the computer.

Information relayed from the sensors to the computer is single line, 1 bit
information. Therefore, there is no need for buffering or routing of information for
the purpose of stalling. However, this kind of manipulation will be later useful in
designing a USB to central core communication system of the signal. This
procedure will be discussed late in the paper in another section concerning USB
integration into the design. The 1 bit line going into the selector switch goes into

                                                                                     67
the control core together with the four bit line from the decoder and the four bit
line from the multiplexer. In addition, the single bit input line from the decoder is
connected to the control core, as well as, the one bit output line from the
multiplexer. The scalability of this section of the design is easily scalable since
the one bit lines from both components will remain one bit while the 16 bit lines
from both components can be raised or lowered as desired. By changing the 16
bit lines on both components, the control logic on both components will need to
change. For the current 16 bit lines there are four bits that control which channel
is utilized. If the number of lines to the sensors is brought to 8, there is a need for
only three bits maximum to switch between the 8 channels. However, if 32 bits
are needed for a much grander design, then five bits are needed for the
switching logic.

Due to various design requirements, not all 16 bit channels might be used, or
however utilized for the specific design specifications. Thus, those lines can
simply be left unconnected to the sensors or other apparatus. Also, those
channels can be connected together if desired. For this project, the channels are
left untouched, meaning unconnected. But coming back to the previous design
logic, two channels can be connected to the same line. For example, if 0000 is
entered or 1001 is entered, both of them will lead to the same sensor. This
method is somewhat redundant and uses extra wire. In addition, it contributes to
increase in the complexity of the design logic which is unnecessary for the
current purpose. As a result, the extra channels are left untouched.

Since the logic components are TTL, there power design is a DC supply with
steady current and voltage going into each component. This serves the purpose
of retaining predictable output on each component. If the power supply was a
fluctuation source, then each component would be available to be utilized during
different time with vary windows of opportunity. In this case, the steady supply of
power allows for a big window of opportunity, in fact, as much as allowed by the
signal sent to it to allow the successful transfer of information. Also, uniformity
across the system is important in maintaining its proper functioning. This is a
major reason in selecting a DC power input to the TTL components.
Furthermore, the DC power source is easier to maintain and control over the
whole system verses an AC. Uniformity in the system maintains proper
channeling of bits from one component to the other. Moreover, the sensors are
designed to handle DC input and not AC. If the input into the sensors was AC
then they would toggle back and forth between on and off, leading to a break
down in the proper functioning of the system. Thus, a DC input into the TTL
components was chosen.

Furthermore, TTL is designed to handle DC and not AC in this case. An AC
current would destroy the components and considerable increase the cost of the
overall project. Also, a steady power supply will assure the power consumption
does not have to go through hills and valleys and having to overcome resistive
reactance, inductive reactance, and capacitive reactance. This is another reason

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why DC power was designed for this project. Low power consumption is
necessary for the project to have a low foot print. Since a smart green house is
the overall branding of the project, low power consumption is very important
property. Due to the low power consumption of the design requirement, the
design of the central control unit had to be designed manually instead of buying a
FPGA board and not used a majority of it.

Subsection 4.1.b – Button Interface

Next the design of the buttons that the physical user can navigate to turn on each
sensor or turn them off. The component has many parts to it ranging from 4 D
latches to XOR gates, AND gates and or gates. The purpose of the circuit is to
count up and count down with the signal sent to the selectors of the multiplexer
and decoder. Thus, traversing through all the channels of the multiplexer or
decoder as desired, with one button for counting up and one button for counting
down. Not all Q not of the latches will be utilized as only the first three are
needed for a four bit counter. Below is a picture of the diagram depicted:




                    Figure 4.3: Counter design schematic diagram

The circuit has three inputs and four outputs. The enable button will be
connected to the source power in order to allow the D latches to always be
enabled whenever needed. The up input increments the counter when needed
from the binary value already present in the D latches. For example, if the latches
hold 0010, then the up counter will increments it to 0011. On the other hand, the

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down counter will decrement the value already present in the latches. Utilizing
the previous value of 0010, pressing the down button will decrement the value to
0001. When the decrement value has reached its minimum 0000 and another
decrement is called, the value loaded is 1111 into the latches. Similarly, the
increment counter is wrapped around in the opposite direction. When 1111 is
incremented again, then 0000 is then loaded into the latches. The simple circuitry
of the device allows it to have low power consumption and efficient use of the
signals without the need for extra components to compensate for complexity and
signal noise.

Powering the components will be a 5V supply for each component. The individual
gates are utilized from TTL microchips that contain several components of the
same kind. This allows for cheap use of each component as there is no need to
buy individual gates or employ a large FPGA when only a very small part of it is
needed.

Overall the interface of the physical buttons that a user can employ is simple, two
buttons for the counter to count up and count down, a button for selection of
reading or writing, and a button for the on or off sensor switching option.




                          Figure 4.4: Button layout design

The counter has the 4 bit bus line due to the multiplexer and decoder needing a 4
bit input line to select between the 16 inputs into the multiplexer and 16 outputs
of the decoder. The Read/Write button is select between the decoder to write to
the sensors and the multiplexer to read from the sensors. Considering that
signals can become garbled or mixed up with noise, each sections of the button
layout has each own lines going into the control core. The buttons themselves
are pushbutton switches that hold a high or low as needed. Pushbuttons are
easy to assemble into the circuit and are cheap, two very important reasons for
using them in this project. Since cost is a big motivator in this case, pushbuttons
are ideal. Also, pushbuttons are easy to find at the local electronics store,
allowing for many experiments to be conducted and pushbuttons to be replaced if
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needed. The power supply of all three sections of the button circuit is only going
to the counter as the counter is the only section that needs active power to
enable and maintain the latches. While the R/W section has only pushbuttons
that are mechanically pushed by the user, the completion of a circuit from source
to the control core is needed in order to send a high to the control core to be able
to activate the read part in the control core. The same applies to the On/Off
pushbutton since the user is applying mechanical force to complete the circuit,
live power is not needed, but a circuit completion is required in order to send a
high to the control core. The actual button layout in location will not necessarily
look like the picture above but very similar to it.

Subsection 4.1.c – USB Translator

Next, the USB unit will be discussed. The USB that is plugged to the laptop or
desktop of the user is in combination with software to allow for the control of the
entire system from the computer. Here several challenges are present. First of
all, the conversion of the serial input and output of USB needs to be converted to
parallel in order for the multiplexer or decoder to understand the signal. Another
challenge is to distinguish the difference in signal between the Read/Write verses
the four bit selector signal choosing which sensor to activate or deactivate, and
also the on or off bit going into each sensor. Overall there are 6 bits that will
control the entire unit. In order to solve the aforementioned challenges a control
core to USB translator is built to handle this kind of workload. The translator is
made of TTL gates, flip flops, and latches. It needs its own power supply of
maximum of 5V for each individual TTL unit in the translator. The USB 2.0 has
four pins: a GND pin, a +5V pin, Data+ pin, and Data- pin. For the purposes of
this project, only three are used, the ground, five volt power supply and the
positive data pin. The Data – pin is used to enable the clock and move the data
forward. The type of USB used is type A which has a flat layout. The translator is
made of 6 S-R flip flops. The 6 flip flops are due to 6 bits that are used to control
the aeroponics system. Each output of the flip flop continues to the central core
where it is connected to the proper device. As the data flows in, the line Data+
handles the 4 bits of location going to the multiplexer or decoder. Number four on
the picture is the lsb and number 1 is the msb. In addition, the On/Off for each
sensor is sent on this line, as well as, the R/W to activate the multiplexer or
decoder. The serial arrangement of the components allows for data to be shifted
to the next location until the program sending data from the computer sends all
six bits. USB usually operates at 120 MB/s which is in the range of what TTL can
handle in respect to S-R flip flops. Therefore, there is no need to slow the signal
down to get a match with the logic design. This is important in dealing with the
proper data sequences paired correctly. The data rate is crucial in getting the
proper bits to align with the output of the unit. High speed flow of bits is not a
major concern in this case since the technology permits for some margin of error
to deal with various environmental and technical concerns. As a result, the flow
rate is correctly implemented in the circuit.


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                          Figure 4.5: Diagram of USB translator

The power to all the flip flops is from the same source of 5V supply DC. Also, the
inverters in the figure are powered by a 5V DC supply. The clock for all the flip
flop is tied together, allowing for the simultaneous update signal and flow of
information from one flip flop to the other. As the data flows, the signal is sent
straight to the control core, but this is a problem. The problem is that once a
signal is present in a flip flop, it might not be the right bit assigned to the right flip
flop, thus it needs to keep flowing down the line until it reaches its final location.
To properly take care of this problem tri state buffers with a AND gate is used to
take care of the time delay until all six bits have been loaded onto the flip flops.
Then the bits are sent to the control core to properly turn on the right logic to
perform the desired actions.

Since there is no need to have a signal feedback into the computer, the design
accommodates only for serial signal from the USB and parallel out from the
translator and into the central core. If there was a need for the central core to
communicate with computer and program, then there would be the reverse of this
design. The flip flops would be laid out parallel connection instead of serial as
shown, and each of the input lines into the translator leading to the USB would
have to be clocked. The clock in that case would serve the purpose of
synchronizing the bits in order to arrange them in a certain fashion for the
computer program to understand. However, the program does not need input
from the central core since as the input is inserted into the program; it updates
itself with the entered information and has no need to have feedback. Since there
is no feedback from the system into the computer program, problems could
ensue. For example, if there is a command to write and the location is given from
the program, an action is expected to happen with precision. But if the program
sends the above desired result but the hardware does something else entirely,
the program will not know about the mistake that just happened. So there is an
error in the system and steps need to be taken to fix the error. The proper
handling of this error is later discussed in the project to better deal with it than
just not do anything.


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There are many reasons for choosing the above design. First of all, the scalability
of the design is very realizable. Depending on the demand, more or less flip
flops can be added to the system. This allows for a much more flexible system to
be constructed. Also, reducing the system to a much simple design from the
current four flip flops allows for easy troubleshooting. Furthermore, the
systematic repletion of flip flop stricter allows for easy troubleshooting as well,
and test design for understanding the system. For example, when a portion of the
circuit is not working properly, the flip flops can be tested individually and the
faulty one replaced if needed. This design is very efficient in handling data the
way it was design for this specific problem. The serial to parallel converters on
the market are expensive in comparison and have extra circuits that are not
needed for the design parameters. Since a green foot print is a major
consideration, low power consumption and as few components as possible is
very important. Moreover, the use of few components will in itself lower power
consumption since there will not be as many power consumers.

Subsection 4.2 – Central Control Core
Specifications

Subsection 4.2.a – Central Control Core

The central core is a very essential part of the hardware system to function
properly. The importance of the central core is to route different lines information
to various parts of the design logic. The majority of the central core or control
core is wires connected properly to their assigned locations, but a part of it is
logic design to assign the Read or Write by using the power supply to the
decoder and multiplexer as a decision device. The S-R flip flop does this job very
well. For example, the R/W command can come from either the buttons or
computer. Below is a figure of the control unit integrated into the rest of the
circuit.




                Figure 4.6: Control core configuration with connections


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As a precaution, the S-R flip flop has both of its inputs tied with a not leading into
the reset in order to have a high sent either to the S or the R of the control logic.
This prevents the flip flop from going into a toggle state of the S and R being sent
both to high. As a result, the output of the flip flop will either be a high or low, but
never jump between 1 and 0 uncontrollably. Also, the simple design of the control
core allows for easy troubleshooting of the device and easy management of
failure when components break down. Since the unit will be in an environment
that will have high humidity due to the needs of the living plant, a simple design is
necessary to replace parts when damaged by the high humidity. Also, the simple
design helps in keeping power consumption low and getting the project to have a
green thumbprint.

Inside the central core, as previously mentioned the design is very simple. The S-
R flip flop serves as the power turn on/off to the mux and decoder in order to
write to the sensors or read from the sensors. The on/off button from the buttons
and from the computer are fused




                         Figure 4.7: Inside view of control core

together since their function is exactly similar and redundancy is reduced to one
wire instead of two wires. The R/W as previously mentioned are connected
together and lead to an S-R flip flop that controls the power of the two devices.
Coming from the multiplexer, its output is connected to the LED display in order
to find out the status of a sensor, whether it’s on or off. Power to the central core
is mainly given to the S-R flip flop since the other components are wires and do
not need power to conduct. The packing of the internal components of the central
core are not inside a TTL packet but largely an area where these components
are present. This design choice is due to the high humidity of the environment

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where components will break down easily. Therefore, insulated wires are much
more easily maintained and tested than the insides of a TTL. Also, the system
can be modified much easier. For example, if extra components need to be
added, the connections are modified accordingly. However a TTL microchip
completely encased would have to add another chip in order to make the
appropriate changes. Also, the TTL chip would require power to turn it on, while
the wire as previously mentioned requires no power. Also, this design choice is
the overall project is an important requirement, the power supply is designed to
provide small amounts of power, which in effects leads to low power
consumption of the components inside the power supply. As a result, low power
consumption as previously mentioned contributes to power savings and a low
environmental impact.

Subsection 4.2.b – Display Properties and Design

The display of the central control unit is very important. It is comprised of two
LEDs followed by an 8 segment display and two 7 segment displays. The display
unit shows information about status of the sensors as well as the sensor number
that is under consideration. On the left of the display are two LEDs. The first LED
on the left is green and it turns on when the sensor selected is active. On the
other side to the right of the green LED is a red LED which glows red when the
sensor selected is off. A high will turn on the green led while a low will turn on the
red LED.




                       Figure 4.8: Diagram of LED display board

The output from the multiplexer is taken and put into an AND gate that feeds its
output to the green LED and the red LED. However before the output goes to the
red LED, there is an inverted to switch the high to a low or low to high. This
ensures that both LEDs are not turned on at the same time, as well as, when the

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multiplexer sends a low that only the red LED turn on and not he green LED. The
low power design of the circuit plays a role in maintaining a low environmental
foot print by utilizing as little power as possible and as few components as
possible. Below is figure that best shows this circuit.




                Figure 4.9: Schematic diagram of On/Off configuration

Next, the display part of the project dealing with the 8 segment display will be
discussed. The 8 segment display is used to display an S which stands for
sensor, followed by a dot to be able to distinguish it from the number display. The
purpose of the 8 segment s display is just for aesthetics and since the display is
made of LEDs, very little power is drawn to turn it on. Since the expansion of the
project to include fore sensors is very important, the s can be used to display
numbers if needed, however, new circuitry has to be added in order to support
the display of three numbers. Powering the whole display is 5V separated into
sections and controlling the current as needed since some of the components
are more sensitive to it than others. For example, the two LEDs can take more
current than the segment displays, thus the segment displays need to have a
lower current going into them.

The 8 and 7 segment displays have the same layout as below, however the 8
segment display has a dot at the bottom right that distinguishes it from the 7
segment display. Below is the layout of both components without the dot. The
letters are different LEDs on the component that are used to guide the
connections to the circuit. The 7 segment display is going to have a pin for
ground, pin for 5V power, and pins A to G are for displaying the number.

Below is the 7 segment display connected with inputs. The program used to build
the below circuit is multisim. Since the MSB is only going to turn on for sixteen
numbers and in those sixteen numbers and only 10 to 15 are going to be utilized
since only four bits are available in this design for selecting location. Thus, the
MSB must display a 1 when 10 to 15 in binary, is sent to the 7 segment display.



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The Boolean algebra equation is: F(x) = D(C+B), where A is the LSB and D is the
MSB and alphabetical order is still obeyed.




            Figure 4.10: Schematic diagram of a 7 segment display in circuit

Displaying the numbers 0 to 15 requires a binary to decimal converter. In order to
accomplish this task, a circuit is necessary to properly take the binary input from
the multiplexer, the four bits that select for location, and convert them to the
proper LEDs turning on and off . Since, efficiency is very important to the project,
a custom designed circuit to handle this job is required. There are 7 Boolean
expressions to the entire circuit with 1 expression for each LED. Available market
ICs that convert from binary to decimal, for example the 74185, utilize a ROM
and are costly. In addition, the chip is out of the market, and making its
acquisition is a challenge. Other chips similar to the 74185 also use ROMs but
are not cost effective and require much more power than the circuit displayed on
the next page.




            Figure 4.11: First half of 7 segment display connected to circuit

                                                                                 77
           Figure 4.12: Second half of 7 segment display connected to circuit

The 7400 series IC are utilized to construct the circuit above. The two types of
TTL ICs are used to create the circuit above: 7411 for the AND gates, 741G04
for the inverters, and 7432 for the OR gates. The 7411 has a set of 3 AND gates
with 3 inputs and one output. The 741G04 has only one inverter with a single
input and a single output. The 7432 has 4 OR gates with two inputs and one
output. For the flip flops in the previous circuits, the 7479 is used to supplement
the D flip flops. This IC has two D flip flops with each containing one output. For
the decoder, a 74158 is employed, which is a 4 to 16 decoder with one input and
16 outputs and 4 bits for selecting between the 16 outputs. For the multiplexer, a
74450 is used but he output is inverted, thus another inverted is added to it in
order to reverse the bits back to their original form. Powering the circuits is not
complicated. Each IC requires a 5V supply with a ground attached to the
specified pin. The number of ICs that are needed is variable and can change as
the experimentation on the durability of the IC with a humid environment is due to
damage some of the components. Also, since some of the ICs do not fit the
design of the project as needed, some modifications to fitting the IC to the
general circuit have to be made. For example, the 7411 has three AND gates
with each gate having 3 inputs. Since the design calls for some AND gates to
have 4 input, 3 inputs, and 2 inputs, the AND gates will have to be tied together
or inputs tied to the same input line in order to produce a AND gate with two
inputs.




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Subsection 4.2.c – Power Interfaces and Conversions

Powering the entire central control unit is a transformer that has been modified to
suit the purpose of this project. A Panasonic power supply that plugs into the wall
with an output of 9V DC and 500mA is used. To properly power the circuit, the
output wire had to be retrofitted to supply all the individual ICs. The ICs are
considered to have very little resistance and therefore are considered to have a
resistance of 2 Ohms since there is some resistance in the system already due to
wiring and internal resistance in the ICs. In order for the circuit to supply the
number of ICs, a parallel structure is devised. Also, if any of the ICs break or
cause a system failure, the other ICs will not be burnt. Once the problem is
recognized, the problematic component can be removed. Furthermore, a parallel
distribution of power maintains equal voltage across all the joints but reduces the
current according to the applied parallel resistance. This property is good
because the current as is currently at 500 mA is too high and needs to come
down. A current with 500 mA will damage the ICs in addition to the LEDs. Since
the ICs normally operate at 20 mA and the LEDs operate at about 25 mA, it is
necessary that the current be brought down to the 20 mA to 25 mA range. A 25
Ω resistor is needed to be placed at 20 junctions, bringing the current down to 20
mA.

On the other hand, the voltage is not affected by the division of the circuit into 20
parallel parts. But since the voltage in each of the 20 sections is 9V, it needs to
be brought down. The ICs and the LEDs operate at about 3.2V to 5V range, and
9V is too high. A 9V differential will burn out the LEDs and cause the ICs to short
out. Also, a distributed network load helps to manage heat as not all active
components are going to be located in the same area. In addition, the advantage
of using a power supply that has already been constructed is that the
management of the AC fluctuations are under control. Also, the noise coming
from the power line is managed properly. Moreover, the ready-made power
supply is not expensive and can be found at a garage sale or at home from old
parts. Making the power supply itself, would be cost prohibitive and there is a
fear of electrocution. Since the power supply that is used has insulation, the fear
of a short from the humidity of the environment that the plant will grow in is not an
issue. Also, the coating of the power supply is plastic; therefore, insulation
against water is really good. In addition, since the power supply will be able to
last a long time, the environmental foot print is good. A long lasting power supply
will not require new resources as a new one will not replace it. Below is a picture
of how the power supply connected to the rest of the current divider circuit is
arranged.

Load is distributed throughout all the branches and has many positive aspects to
it as mentioned previously. The scalability of the project was also a prime
property. Since the distribution of power is in parallel, new branches can be
added without affecting the whole system. At some point the added branches will
affect the system due to the extra load, but the overall resistance has to be

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brought down to relatively close value that it was before the addition of the new
branch. In order for this to be accomplished, each of the 25 Ohm resistor values
would have to be brought down. On the other hand, if the number of branches
has to be reduced, then the 25 Ohm resistor value has to be brought up. Off
course all the loads on the system have their own access to ground or an
individual ground if needed. But for this design, all the loads share a common
ground.

Furthermore, if the power supply becomes damaged a new one with different
specifications can be utilized, but changes to the resistor value have to be made.
Since power supply failure is not impossible, the circuit design has to be able to
handle a change in power supply without major reconstruction. Another reason
for the parallel design is that the system can handle a power supply with lower
power rating or greater power rating without much change in the supply voltage
and current. However if there is a need to change the power supply with one that
has dramatically lower or higher voltage and current output, then the 25 Ohm
resistor values can be manipulated accordingly. Also, if the power rating output of
the new power supply has really low power rating, then the 25 Ohm resistors can
be significantly lowered to accommodate for the lower voltage.

Moreover, all the loads in the circuit can be dramatically different that its close
neighbor, so different current or voltage supplies to it can be arranged. Since all
the branches are independent in voltage, but not current, then the voltage is the
factor to be manipulated if required. For example, if a branch needs high current
and the circuit does not supply it with adequate amps, then a transformer with a
capacitor and inductor can be used to raise the current supply. On the other
hand, if the voltage supply is insufficient, then the 25 Ohm resistor rating can be
lowered to accommodate the specifications. The flexibility of the system is a
great advantage when considering that parts can become obsolete or damaged
and changing them is not a problem.

Subsection 4.2.d – Environment of Operations

The light in the environment the aeroponics electronic system will operate in will
be determined by the type of LEDs to power the plant. Since most plants require
a spectrum from 480 nm to 620 nm, this is the range that the LEDs will be in. The
480 nm is in the blue range and the 620 nm is in the red range. Plants need both
blue and red colors to function properly. Chlorophyll in their leaves has evolved
to absorb these two light spectrums and make food from it. In this project, the
electronic equipment will be exposed to light; therefore, it is important factor to
consider whether, the light frequencies will damage the equipment. From
information given by various texts books and research papers, silicon is turned
into circuit by etching using lasers and various acids to construct the proper
components on the dye. Thus assuming that light has some effect on electronic
equipment would be a smart guess. However, light does not damage electronic
equipment under the earth’s atmosphere, unlike in space. This difference in

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effects is due to space having a lot of ultraviolet radiation and other for kinds of
radiation. Also, in airports, electronic equipment is sent through an x-ray machine
and every time the electronics seem to experience no damage.

Furthermore, the environment that the exposed chips will be in will have no
ultraviolet radiation, alpha radiation, beta radiation, or gamma radiation. In
addition, most damage to electronics comes from solar flares and solar winds.
These factors are very powerful in space but not very strong in the lower
atmosphere due to there being a several layers of gasses that shield the earth
from such forms of radiation. If damage from electromagnetic radiation becomes
a problem the cheap components can be replaced and an aluminum foil or some
kind of electromagnetic shield can be placed to protect the electronics from
damage. Given that the majority of radiation present at the habitat of the plant is
blue and red, there is no need to worry about electromagnetic radiation ruining
the electronic components.

Next the moister and humidity of the environment will be discussed. Moister and
electronics do not mix well at all. Since moister cause shorts in the system, this is
a major factor. In order to elongate the lifespan of the electronic equipment, the
humidity of the environment must be kept at low enough levels in order for
moister not to build up on surfaces. However, since the plant needs a moist
environment to grow healthy, this is a challenge. The humidity for the plant to
support itself without the leaves having to dry out or a lot of strain to be placed on
the roots, the plant must have 40% to 90% humidity. And the average humidity
must be ranging from 50% to 70%. The higher the humidity the better for plant
growth as it simulates its environment. The humidity the water molecules in the
air will not concentrate themselves unless the air begins to cool. As long as the
air stays warm there is no concern about moister building up on the surface of
electronics.

The surface areas under most concern are the non-insulated wire connections.
These wire connection can short with one another and cause unpredictable
results. For example, if the exposed wire connections are near the power supply,
then a short there might burn the fuse box or turn off the magnetic switch in the
fuse box. The latter being a harmless scenario since the magnetic switches can
be turned back on. The worst case a fire starts that consumes the area and
spreads to other areas. This scenario is unacceptable; therefore, measures have
to be taken to minimize this kind of damage. Steps to taken in order to minimize
the worst case, is to insulate the wire connection with electric tape and have as
few exposed connections that cannot be taped shut. If connections were not able
to be taped with electronic tape, then the exposed components were placed as
far away from each other as possible. The distance allows for moisture build up
but would require a lot of water buildup on the exposed surfaces in order to
cause a short.




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Heat is a major component in chip failure relevant all other the industry. Thermal
runaway is the largest contributor to what causes unit to break. Thermal runaway
happens when chips continue to get hotter and hotter as electron flow spreads
uncontrollably, causing the rise in heat as a result. Given that the environmental
conditions that the plant will be enclosed in, heat through environmental factor is
the main concern rather than thermal runaway. Since the strain on component
performance is not something to worry about as the demand for raw computation
is not needed in this case, rather just a few calculations.

The environment the plant and electronic components will be housed in ranges
from 15oC to 25oC with some leniency but controlling the temperature when it
reaches much higher ranges. The absolute maximum that the temperature will be
allowed to reach is 40oC. A temperature this high will need to be lowered as
quickly as possible in order to not damage the plant, but electronic components
can very well handle a range that high. Most ICs manufactured today can handle
temperature much higher than 40oC. The concern rises from locked pockets of
air where the temperature can reach levels higher than 40 oC. Since the ICs can
handle a higher temperature range, the insulation of wires and connection are
the main focus. Plastic insulation can become soft and even melt. When this
happens, shorts can occur and cause a fire or system failure. A system failure
can be undone by doing troubleshooting and replacing the bad component, but a
fire is very damaging to everything. In order to prevent the worst case from
happening and even component failure due to heat, the circuitry will be placed in
an open environment where there is enough air flow to impede the rise of heat.
To accomplish such a task, the components will be placed with enough space
between each other that even if the worst case occurs, the nearest component
will not catch fire and spread the flames. A fan can also be utilized to get airflow
in the circuit but the fan requires consumption of extra power, which is not a very
environmentally friendly approach to a project that is supposed to be a green
project.

Next the people involved in the maintenance and use of the system can have a
major impact on system performance. People will stress the system in ways that
are not able to be predicted or simulated. Careful, understood, and respectful use
of the circuitry will contribute to no accidents. Taking food to the electronic
components and causing a spill is unacceptable. Such accidents can cause units
to malfunction. For example, drinking soda and placing the cup on top of the
circuit can cause a short from the water droplets forming outside the cup and
falling onto the electronic board. This behavior will lead to components shorting
out and as mentioned before, shorts can lead to fire. Also, besides bringing food
to the work area, not replacing units when they become damaged is another
misuse of the circuitry. Not replacing units will cause the circuit to malfunction
and not be able to control the sensors. When the sensors are not able to receive
information from the control unit, then they will not be useful as the plant will die
due to negligence.



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All the negative side effects as aforementioned can be avoided by properly
replacing components when damaged, not taking any food to the plant area
except for the required minerals that are going to be added to the water, etc.
Also, body parts should be kept away from live electricity. When this rule is
ignored, electrocution ensues. Electric shock is a very real threat that can be
deadly. For this sake, many components will be insulated but when the circuitry
is not properly taken care of, exposed wires and a human hand on those wires
will lead to shock. Depending on a person’s medical condition, a small current,
for instance 20mA, can be very deadly. Death is very unhealthy and thus should
be avoided. Taking care not to abuse the electronic components by maintaining
a clean environment will contribute to a safe workspace and a healthy plant. The
rules are necessary and are not made up for the sake of bureaucracy.

The indoor environment has its benefits and it negative side effects. First of all,
the elements are avoided which is a big plus for the electronic components.
Whether is under control as climate in an enclosed environment can be
manipulated. For instance, strong wind to knock over equipment and damage
them in the process is not a concern. Furthermore, bugs are a troublesome factor
when they crawl in small crevices in electronic equipment and make their nests
there. This leads to components being chewed out and wires being exposed,
creating a risk of electrocution to the user. Besides bugs, other animals such as
raccoons which are creatures of curiosity might end up chewing on the wires and
cutting them as a result.

Water damage in the outside environment is a large factor. Since rain can short
out connections and inside there is no rain. Water damage is a major concern
when there are live wires. Water flow into the circuit will completely burn out
connections and severely damage chips. Besides the connections burning out,
the problem of rust is a concern. However, since the components are inside there
is no need to worry about rust. Also, maintenance from rust damage is not
necessary. The reduced need to replace components due to rusting reduces long
term costs of maintaining the system.

Furthermore, exposure to the sun can cause components to oxidize. For
example, insulation on wire become rusty and wears out when exposed to
sunlight over a long period of time. Since the wires are indoors, the oxidation of
the material will not occur and as a result elongate the lifetime of the
connections. The control light of the environment is a huge plus, since the light
can be directed away from electronic components. As a result, the electronic
units will not be under oxidation processes resulting from sunlight. As mentioned
before, the light type in which the plant will be exposed is not the kind that will
damage the plant.

Moreover, the change in whether temperature causes expansion and contraction
of units. This constant expansion and contraction will damage the epoxy casing
of the chips. Besides the casing being damaged, the soldering joints will also

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suffer from thermal expansion. The consequences are that the soldered joints will
fracture and lead to poor connections. Poor connections will not allow the control
unit to function properly. To fix this problem, simply soldering the components
back is one method, but it this is a nuisance, then using a bread board to connect
the different components is a possibility.

Due to the plant’s electronic control equipment being located inside a housing
unit, the above concerns are eliminated. This is a huge plus for longevity of the
components and reduction of price to replace the units. When the maintenance
cost is reduced this adds to the overall likeability of the project to the user. Also,
the low cost makes it possible for production and maintenance in an area where
financial resources are scarce. In addition, this project is appealing to someone
who lives in an area where finding electronic parts is a hard task since the
components would be rare or unattainable for some reason.

Subsection 4.2.e – Similar Technologies

Similar technologies exist that would have aided in the construction of the circuit
tremendously. For example, the MAX1661 and it cousins MAX1662 and
MAX1663 convert from serial to parallel and back to serial if needed. According
to its main website, the main application of the MAX1661 it to control power-
plane switching applications in a motherboard to handle the switching of point of
load from a 2-wire SMBusTM in addition to controlling voltage regulation in battery
using applications, such as notebooks. The unit can handle 28V DC line, thus
being burn out by a small voltage as the one required by the project is not a
concern.

Although the unit does not specifically mention USB connectivity, the purpose of
this part is to handle the successful conversion of data from serial to parallel. The
data handling would require the IC to take serial output from the computer and
then work that data into a parallel simultaneous output. Converting the data flow
from one to the other carries the problem of one bit unit going faster than the
other as the computer takes its time to handle other applications. This factor is
something that is very hard to account for both in the circuit design in this project
and Max1661 chip. However, the commercial chip seems to have solved the
problems by having the bits buffer until all the bit units are present. The unit also
has an active low SMBSUS control input that switches between two data
registers for the purpose of storing information to transform it into serial to
parallel or vice versa. The operation temperature is from -40oC to 80oC which is
really good for the plant environment at around 25 oC but this temperature is an
average temperature and the environmental heat cannot become greater that the
IC’s operating temperature. In terms of current, the IC can handle from -1mA to
50mA which is a really good range considering surges in current if they happen.
Also, the wide range in current is really good quality for handling instability in the
system. Furthermore, the IC has a steady, linear rise in supply current vs. supply
voltage. A linear current vs. voltage property elongates the lifetime of the IC, and

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allows for easy integration of the IC into a system. Since a linear output will be
produced from this linear relationship, there is no need for regulator circuits to
handle the low swings and up swings. Definitely a good quality when looking at
cost savings.

A major negative quality is the IC’s current relation with temperature rise. As the
datasheet reveals, the rise in temperature lowers the current limit of the IC. The
fall in current begins at about -40oC and continues to about 80oC, which is the
maximum operating temperature for this particular component. The room that the
plant will be housed in together with the electronic components will not exceed
40oC, since the plant would not be able to live and reproduce successfully, and
the water from its body would evaporate at a greater rate than it can replenish its
supply. Moreover, the power delay vs. temperature is another good quality about
is IC. From the IC’s datasheet, as the temperature increases, there is a small
change in its power presence. For example, at 20 oC, there is a 20µs delay in
delivering power. Since the technology is silicon, some power delay factor is
excepted as temperature rises.

The cost of the device is around $60, just the IC itself in addition to taking time
for shipping and shipping cost on top of the IC cost. The cost of the designed IC
is much less at about 10 dollars and its custom design allows for power savings.
MAX1661 contains many components inside of it. Besides the monetary cost, the
IC uses a lot of components inside of it. These components consume a lot of
power as evident by the temperature range under normal conditions of the IC. In
addition to power consumption, which does not make the IC very green in terms
of environmental savings, the complexity of the chip does not aid in prolonging its
life span. Since many components means a lot of factors affect each small
component, this increases the chances of the IC to malfunction and cause the
whole system in the project to go wrong. In the long run, this is not very
environmentally friendly since the part would break more often than a part with
fewer components. Eventually, leading to more chips being used than would
have normally consumed by use than another IC with fewer parts. The reason
this chip was not used in project is largely due to cost and high power
consumption. In addition, integration with other components of the project would
have led to modifications to the project in order to accommodate for the
requirements of the Max1661 chip. Furthermore, the environmentally friendly
approach to the project would be damaged by the chips reputation as a high
power consumer. Below is a picture of the Max 1661/1662/1663 chip. As it
reveals there are a lot of components that deal with handling data in serial and
parallel. In addition, if there is a need to replace any small components; such as
a multiplexer, the entire chip would have to be thrown out and new one takes its
place. This is an expensive endeavor due to the high cost of the chip. Further
leading to more waste and consumption of scarce resources, which is not a good
environmentally good decision.




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                    Figure 4.13: Figure of maxim circuit of counter
                     (Reprinted with permission from Maxim [9])

Since serial to parallel conversion is a crucial part in the project for handling the
computer to circuit and sensor communication. Therefore, this portion of the
paper took some room to discuss the subject. Moreover, since the chip is not
custom designed by any of the group members, fully understanding the
functionality of the Maxim chip is a challenge that has many blind spots leading
to improper integration of the IC into the senior design project. For example, the
delay time from one section of the chip to another can have severe
consequences to the mux select on the other part of the project if the 4 selector
bits come later than the input it the decoder. From observation of the schematic
diagram, the chip has a thermal shutdown default function just in case the unit
gets too hot and shorts itself from the high heat produced. This is a good quality,
but the operational temperature of the plant environment will not exceed 40 oC.
Also, the extra component requires power to run and that lead to greater power
consumption in the overall chip. Given that the project is a green project, power
consumption is something that must be kept low.

The LCD screen is a great display platform but there are many disadvantages to
this technology for this purpose. First the advantages will be discusses and then
the disadvantages. The LCD screen is made of molecules aligned in the middle
of two transparent polarizing filters and two transparent electrodes. The screen
has no light source, making it difficult to read it in the dark. While the LEDs have
their own light source and can be seen much easier in the dark than LCDs. The
component in question for this technology comparison for the purposes of this
project is DEM 16217. The component has a LCD panel display of 2 by 16
characters. This is a great property when considering that a lot of letter can be
useful in conveying a full message without using short hand. In order to get the
message to the LCD panel, a LCD controller is used. The controller has an 8 bit
bus for creating the message, an R/W, a register select and ground terminal with
power supply for the liquid crystal drive and a 5V supply for the terminal module.
Also, there is an independent backlight for helping with the problem that LCD

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screens do not have their own light source. Furthermore, there is a segment
driver that controls the signals that go into the LCD panel.

The storage conditions are ideal for the plant environment operations. The
operating temperature of the LCD circuit is at -20oC to 70oC. Since the plant
environment will not exceed 40oC, the operation conditions are within reasonable
range for this project. Powering the unit is a -15 V to 7 V range supply line with
the -15 V going to a different part of the circuit than the 7 V. Optimally speaking,
the voltage range is from 4.5 V to 5.5 V with a supply current of 0.35 mA and
tolerates about 0.6 mA. The low voltage use and the low current consumption
make this component an ideal device for this project. Considering the low power
usage and efficiency of the unit, this is a very good unit to be included in a green
project design.




                     Figure 4.14: Controller circuit for LCD screen
            (Reprinted with permission from Display Elecktronik GmbH [10])

As depicted by the block diagram, the controller comes before the LCD panel
and it directs the information into it through the 16 bit bus. Also, there is a 40 bit
bus line for choosing between the segments in the display unit. From the LCD
controller there is also a control signals line that deals with commanding the
segment driver. The segment driver controls the other 41 to 80 segments, which
is the bottom half of the display panel in this case. As noted, the display panel is
made of two rows of display units, each having smaller sections where even
smaller squares that are the pixels reside. The individual pixels are controlled by
the com1 to com16 bus line and the seg1 to seg40 together with seg41 to seg80
control the individual segments. The command lines can be attached to a simple
keyboard that can be modified to send certain code segments in 16 bits to
represent the display units for this component. Also, the back light is present to
help the legibility of the LCD panel, but is independent of it with its own power
supply and operation. The data flow rate is not very relevant in this case since
this design model is simplistic in nature and has very efficient design
characteristics.


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The reason this unit was not used in the project circuitry is that there is no need
for something of this magnitude. As long as there is a display unit that can
display numbers in concert with the select portion of the button interface, then the
required need is satisfied. This unit has many capabilities beyond the needs of
this project, but if the project was to be dramatically increased in capacity, then a
display of these characteristics is required. However, a much more complex
design is needed to satisfy the new requirements set by the DEM 16217. But for
future references, the DEM component will be very useful.

Next the counter used in the project to traverse the sensor list on the display is
discussed. The counter designed for this project is made of gates and the two 7
segment displays. Designing the part was to have a minimalist and efficient
construct. Since very few gates are involved compared to available market
products, in terms of power usage, the counter is very efficient. Also, since the
circuit is custom designed, there is no need to have other circuits to modify the
signal for the purpose of fitting it in the project. Also, market circuit cost is higher
than the individual 7400series IC. The 4511 is the decoder circuit that is used for
this purpose. This particular IC uses latches that lead to the decoder part and
then the drivers that light the LEDs. The price of the 4511 from Newark is $0.518
which is a very good price and it is encapsulated in an epoxy case, really good
for the environmental conditions that are required. The reason this component is
no going to be used in this project is due to shipping restrictions. The chip could
not be found to be available within 30 days. Due to this timely constriction, it is
prohibitive to consider this part for the project.

Other similar products are too complex and costly to be considered a viable
option for this project design. Complex ICs consume too much power to be
considered a green alternative to the custom designed circuit’s efficiency.
However, the complex nature of those circuits brings with them additional
features. For example, a greater number of bits for higher values to be displays
on the LED display. Below is the diagram for the 4511.




             Figure 4.15: A BCD circuit that connects to a 7 segment display
                        (Reprinted with permission from NXP [11])

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Subsection 4.2.f – Testing and Troubleshooting

Troubleshooting is a very important part of the project as it describes in detail,
what is the user to do when a problem is encountered. Besides the problems
encountered, the troubleshooting portion helps to familiarize the user in case
there is a need to replace a part or find alternates to a part.

This portion of the troubleshooting section will talk about eh physical interface of
the electronic components: the buttons. The buttons have four pushbutton types
with each having a specific function. The four pushbuttons are an R/W button, an
On/Off button, and one for counting up and one for counting down. When there
are missing components, there certainly is a problem with the number of buttons.
The button interface can have more, but not less buttons. To clarify, there can be
a button just for R and another just for W or one just for On and another just for
Off. When there are less buttons then there is a mistake with putting the part
together and therefore, should be reconstructed properly.

The counter used for selecting between the different channels in the multiplexer
or decoder is very important. When the selector does not count properly, then
sensor will be skipped or repeated. When the output from a sensor is only 0 or 1,
it is difficult to know whether the sensor has switched to another. In order to solve
this issue it is best to disconnect all sensors that are of no interest and turn on
the one that is important. Letting all sensor to stay low is also a compensatory
method for not having 16 sensors and taking care of the null cases. Afterwards,
start counting and observe whether the number of increments is appropriate for
its case. For example is there are 16 sensors and the first sensor is the only one
that is high, then there should be 15 steps before the same sensor is reached
again. Thus, when a high is encountered there should be another 15 steps
before another high is encountered. If this does not happen then there is a
problem with the counter. In order to fix the counter then the multiplexer, since R
is what was considered for this case, needs to be taken out of the circuit and
examined on its own. To test the multiplexer is simple and experience in
electrical engineering is important to make this step an easy one. When writing to
a sensor, the decoder is at fault if there is a mistake in output. To further
investigate this issue, the decoder must be taken out of the circuit and investigate
individually. Running tests on the decoder is simple and since an electrical
engineer is expected to read this, then there is no need to go into detail how to
test a decoder.

When the buttons are pressed but there is no change in the output or input of
information and the multiplexer along with the decoder have been tested, there
might be a problem with the physical buttons, if the sensors are still working
properly. There might be several problems with the sensors. First of all, the
connections in the sensor could be shorted or the sensors could not be making
proper contact. If the sensors are not making proper contact than no action will
be performed by the circuit, thus a method must be devised to test this. To do

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this, connect the button to a multimeter with positive end of the multimeter
touching one of the side of the buttons and the negative side, the other lead of
the button. The multimeter should be set to measure resistance. When the button
is pressed, there should be no resistance or almost no resistance reading on the
meter. The results reveal that the connection has been made when the button is
pressed down. The opposite result in the multimeter will follow with some
resistance reading or infinity if the button does not make a healthy connection. At
that point, the resistance reading of the multimeter is so high than the button
needs to be replaced with a properly working pushbutton.

The previous problems can occur due to many different stressors on the system.
First of all, the mechanical wear and tear happens when the metal part has been
pressed so many time that the metal breaks, causing either a short or a
permanent open connection. Also, if the buttons are pressed constantly and very
fast for a long period of time, then metal fatigue will happen and this will also
cause the buttons to break.

Next, the sensor will be discussed. The sensors are a very important part of the
project. The sensors are responsible for creating information about the system
that is later used to make decisions by the user. When the output from the
buttons is the same regardless of the conditional status, then there is a problem
with the sensors themselves if other problems have been ruled out. The number
of sensor does not matter as each sensor is tested individually in this method.
Sensor output is either going to be a zero or one. To test each sensor if it is
properly working then, the sensor is removed from the aeroponics environment
and isolated.

A multimeter, as the previous test required, is needed to solve this issue. A
sensor is turned on by making the connection and then a multimeter is used to
test the resistance across the sensor. The multimeter reading should display
either a really low resistance in mOhms or no resistance at all. If this happens
than the sensor is working properly for sending a high. Testing the sensor for
sending a low is just as easy. The sensor is put on low by opening the
connection and then a multimeter measures the resistance of the connection. If
the connection resistance is extremely high, for example in MOhms or infinity,
than there is an open connection, revealing that the low part of the sensor is
working properly. If the above mentioned results do not occur than the sensor is
broken and a new one needs to take its place.

When the sensors themselves are working properly, but the connections leading
to the sensors are poor, then the sensors will appear faulty. The symptoms for
this kind of errors are very similar to faulty sensor; however, the senor is not the
one at fault. The sensor will appear to be sending either a 0 or a 1 all the time
regardless of conditional status. In order to test for this case, the above
mentioned actions should be taken and then the connection tested for shorts or
opens. In order to test the connections themselves, the wire is taken and

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examined with a multimeter. To fix this problem is very easy; the wire is replaced
and soldered to the sensor.

The soldering joints themselves can become faulty. Through the years the wear
and tear of moving he sensors from one location to the other, can damage the
solder joints. The symptoms of this case are very similar to a sensor being faulty
or wires appearing damaged. In order to fix this problem, the soldering joints are
first disconnected from wire to sensor. Then the wire is replaced or cleaned with
a hot soldering gun by melting off the excess flux or a section of the wire cut off.
Once that happens then the wire is ready again. On the other side, the sensor is
cleaned the same way the wire. If the sensor is a chip, then a heat sink is needed
between the chip and the heat source so as to no damage the chip from the heat.
Once the sensor connection is cleaned, then the wire and sensor are soldered
back together. To test the connection, the sensor is run through some tests. Firs
it is turned off and then the multimeter reading is performed. Once this passes, if
it passes this test, the sensor is turned on and then the multimeter test is run on
it. If the tests are not passed, then the soldering job was not done properly.

Once the buttons and the sensors have been tested, next is the test for the USB
translator and software portion. The USB translator can have many faulty outputs
due to the data rate, software errors, computer errors, etc. Translating the
information from serial output coming from the computer to parallel output going
into the control core is an important step in making sure that the software can
communicate with the sensors.

To begin with, the translator has to be first test for output. Testing this part is very
easy. The output of the sensor is seen if there is an output when there is an input
from the software. When there is a direct link between an entry in the software
and in the output of the translator going to the control core, testing can begin.
However, if there is no output at the mentioned location, then smaller units have
to be tested to make sure that the error can be isolated. When an input is entered
at the software end of the project, then an output matching the input in binary
should occur. If there is an output and the output matches the decimal value in
binary, there is not error with the system. On the other hand, if there is an output
but the output does not match the decimal value then there is an error in the
system.

To first check where the error is located, the decimal input numbers are varied to
observe a pattern of output if there is one. If a pattern of output is observed, then
there is an error with physical connections or software layout. To eliminate the
physical connection problem, the translator is tested one bit at a time for correct
faulty output. Once the incorrect bus line is found, the line is either tested for
physical faulty connection or further software error. Once the error has been
found, then observation is move to another bus line and the procedure is
repeated. However, if the error is with the software then, the code is checked for
errors and fixed accordingly.

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There can be many errors that would have nothing to do with either the translator
logic being wrong or the software code being incorrect. For example, as
previously analyzed the solder joints can become faulty or the wiring can wear
out. Since this part of the circuit is mostly a solid microchip, the problem of wear
and tear is not a major concern.

Timing of information relay can cause havoc if not properly synchronized. The
flow of bits can cause some bits to take the spot of other bits. Once information
becomes garbled then the aeroponics system will not work correctly. Mixing of
information has two sides of attack. First the easy side is the software related
issue. Information being sent with the incorrect pattern of bits yields incorrect
results. Also, when the information is read, the sensors under question will
appear as faulty when they are working properly. Narrowing down the problem to
time inconsistencies, the other tests are performed first and sensor error, button
error, etc., is eliminated first and then the time issue is resolved.

Hardware sending information too fast or too slow for the wrong bits causes time
problems as well. For example, sending the information through a mux before the
bits that control the selector are received will send the information to the part of
the circuit. Thus, the selector bits in this case need to arrive before the
information to the mux is sent. The same applies to the decoder. This issue is a
very tricky issue as all the other tests need to be done first, and sometime the
output from time delay can be correct and at other time is incorrect. Catching the
output when there is an error can be a chance of luck or fairly obvious if the
proper tools are available and the system is understood completely.

Displaying the information is a LED display with a letter and two 7 segment
displays revealing information about the sensor number. The 8 segment display
containing the letter is easily diagnosed. If any of the LEDs that contribute to
make the letter do not turn on, then there is connection problem or one of the
LEDs is burnt out. To make sure the latter is happening, each LED is tested one
at a time with a high and if it turns on then it is ok, otherwise a new 8 segment
display is needed. In the connections, one of the pins could be loose and that
could also contribute to the faulty result.

The two 7 segment displays are a lot trickier to find the errors in since the two
segment displays are connected to the counter. Once the counter is established
to work correctly, then the work on identifying the problem with the two segment
displays can begin. First, each individual LED has to be tested to make sure that
is responds correctly to a high and low signal. Once that happens, one of the
LED’s is put on a breadboard and tested by counting in decimal notation. If all the
numbers display correctly, then there is no error in the LED and the fault must be
sought elsewhere. However, if there an error then the problem became a
complex one. Since the counter and wire connections have been ruled out as
faulty, and the LED itself was proven to work properly, then the mistake might be

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in the connections. Connecting the wrong wire to the wrong LED on the segment
display. From this information, when the LED is being sent through the counting
routine, there should be a pattern that develops that reveals which LED is
connected wrong. Once this problem has is solved, then the display system
should work correctly.

LEDs themselves coming from the manufacturer can be faulty and therefore
should be checked prior using in the project. Due to this fact, in the project
design accommodated for leniency. For example, the project is defined into small
parts that can be segmented and each replaced individually without the other
parts being damaged in the process. The LEDs are a perfect example of this
intention. Once an LED display is broken then it is simply taken out and replaced
by another LED display. The integration of the 7 and 8 segment display is
discussed in another section; therefore, there is no need to go into detail how this
integration works. In order to understand its part in the electronic design, that
section is necessary to be able to replace with an equivalent part.

Subsection 4.2.g – Conclusion On Central Control Unit
Design
In conclusion, designing the project was very enjoyable. Bringing together the
whole knowledge gained within a single project that can be admired. The many
different aspects of project that led to the whole and seeing how they combined
themselves into a single unit consolidated my learning of small units into a
system design aspect. The project had many sides to it: design, analysis, re-
design and re-analysis, testing, environment conditions, and user friendly design
and testing.

The project design was the most involving part of the entire procedure. Since
every part of the project has to be considered into the whole part without having
a whole part is difficult in design aspect. When designing the small units and then
designing another part there had to be many redesigns in order to optimize for
the new units that were put in. This led to constantly testing portions of the
project in order to maintain a working design as new parts were added.
Dynamically altering the project as reassessments were conducted helped to
better understand the purpose of each unit in the whole.

Testing the project for flaws or performance is a challenge since not every case
is possible to consider. First of all, the environment is expected to be from 20 oC
to 25oC with humidity ranging from 50% to 90%, same as the Florida air carries
the majority of the time and with LED lighting in a very specific wavelength. Since
the lighting will no carry ultraviolet light, then damage to the electronic equipment
due to EMF long term exposure is not a concern. Also, the components are going
to be encapsulated in epoxy casing and wires have rubber coating, shorting is
not a major concern. The long term exposure to these factors will have some


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effect on the display units, meaning the LED display, but since the 7/8 segment
displays are cheap, replacement is not a concern.

The purpose that the project as a prototype is to serve is to prove that a cheap
aeroponics system can be built. The future of food supply is at crossroads with
the explosive growth in population and waste due to long transportation cycles. If
food can be locally grown then, prices of various vegetables can be brought
down. A perfect example of this is that since fuel prices keep going up, the price
of food goes up naturally. Also, for several food growing seasons, there have
been many cases of salmonella and E. Coli. If food can be locally grown, then
there is sufficient isolation from one outbreak to the other to not damage food
supply line or infect a lot of people.

Moreover, the leaking of various nutrients into lakes, streams, and underground
aquifers is a major concern for current and future generation. The leaking of such
nutrients causes ecosystems to go out of balance and cause outbreaks of algae.
Such outbreaks disrupt the food chain of various regions and do affect human
wellbeing. Aeroponics systems recycle their nutrients as the water is sent to the
roots and back to the water tank, and back to the roots again. Besides the
nutrient loss and leaking being minimized, water loss is also minimized. Water
loss minimization is very important where water is scarce. For example, desert
regions or natural resource poor regions, can use an aeroponics system to
minimize their water loss.

Powering the aeroponics system is very easy. Plug the power supply into the wall
and then command the system from the button interface or computer interface.
Since the power usage of the system has to be minimal, a solar panel can be
attached to it to replace the wall power supply. This fact is very important in poor
regions where electricity is not available, or desert regions where sunlight is
plentiful. The future for this kind of design is very fruitful due to expansion of
production, efficient design, low maintenance cost, cheap replacement parts, and
efficient monetary build.

In the end, designing a project with other group members is mind was a new
experience that was not available until now in a project of this scale. Overall, the
project taught me to better communicate my ideas to other group members and
find ways to keep everybody in touch with what is happening. This team
challenge encouraged everybody to stay connected and well informed in order to
better their design. One of the greatest challenges of this project was that one
team member had to finish their design in order for another to being theirs.
Eventually what occurred was that all the team member had to start the project
early in order to have enough time later on to modify based on the requirements
of other team member’s design.




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Section 5 - Communications Design and
Research
The idea is to create a project with the vision for a future. Due to time constraints
and other responsibilities, it was necessary to simplify the project as much as
possible. However, it is important and necessary to develop a great product for
this class, but to also think about prolonging its relevance and to keep developing
new updates and technologies based on what is being cemented today. The
students of today will bring the technologies for tomorrow, making it important for
the project to develop this skill.

Subsection 5.1 – Wired vs. Wireless
Communication Research and Design
Perhaps the most important part of the project (Smart/Green House) is the
communication required between the electrical components, the software and the
user. The criteria employed to choose what the project will be using for the
communication aspect was based on the strength of the signal, the rate at which
information can be exchanged, practicality, cost efficiency and customer appeal.
It is understood, wired communications would have the advantage over wireless
when it comes to strength in the signal and perhaps cost efficiency, however it is
at a disadvantage when it comes area reach, aesthetics and customer appeal. In
order to proceed, the first step was to make a decision between using wired or
wireless communications, making it necessary to research specifics on different
wired and wireless products.

Subsection 5.1.a - Wired
The most popular communication wire is the Ethernet cable; it is used in many
offices and universities as communication between local computers. In the
project, the usage of the Ethernet cable as a way of communication between the
house components with the main house regulator. The Ethernet signal's strength
and reliability, its relative cheap costs and as a way to be more work efficient and
therefore it is preferred. The average Ethernet network is considered to be fast,
with transfer rates of up to 100 Mbps. It is a more secure way to communicate
and it is not prone to interference.

Ethernet started as a wired version of a wireless network, the Aloha network. It
was invented in 1970 by Norman Abramson and his collaborators. He
contemplated a way of communication between the islands and the mainframe
computer at the Honolulu campus. The devices transmit packets to a central
communication node attached to the mainframe computer; finally a device


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concludes that its packet has been delivered to its destination depending on the
acknowledgement sent within a pre-set interval of time.

The cable Ethernet works very similar to the Aloha network, with a device that
waits for the channel to be idle before transmitting, it then listens while it
transmits and in case of collision, aborts the transmission. the carrier sensing
and collision detection mechanisms reduce the time wasted by collisions.

The Ethernet networks provide performance advantages and cost efficiencies
that are better than other networking technologies, the problem with this
infrastructure technology is that Ethernet has no security. So even though it may
save the project money, it may expose the customer's to unauthorized monitoring
and even theft. The issue of space efficiency also comes to mind, with all the
cable communications between the main controller and the components placed
around the house, there might be a possibility of cable mess and the potential
customer might not want to sacrifice aesthetics and space.

Through the calculations, the efficiency of an Ethernet random access scheme is
well below 100% which is obviously not ideal. In order to fix this, the division of
the time into N slots and make the first node use the first slot, second node use
second slot and so on (this is called time division multiplexing). This can achieve
full 100% efficiency and there would never be any collision. There are a few
problems that arise with this. The initial cost is high, a problem for one user can
sometimes affect others and each user requires a precise carrier frequency.

Subsection 5.1.b - Wireless
The wireless communication is increasingly popular in the commercial and
professional world. It provides a series of advantages over the Ethernet cables
that cannot be ignored. Wireless gives the ability to move components around
the house without having to do any rewiring. Since it is a cable-free network,
there will be no problems with the space consumption or the cable mess around
the main controller, and it is also relatively easy to install.

The Bluetooth module is a very good alternative as a cable replacement
technology; the importance of communicating with the interface is still the focus.
Having in mind that in a smart house environment there are constant
improvements and upgrades or changes to be done, the device should provide
the option to be programmed with a microcontroller, this is done for design
flexibility. With bigger budgets, more improvements can be done to the smart
house, inclusion of screens and connection strength indicators may be applied,
among others. Making it essential for communication between the Bluetooth
device and a microcontroller. The idea of a smart house is not only to simplify the
lives of others but it is also to be energy efficient and ultimately, environmentally
friendly. Turning the focus of attention to power consumption as well. It is not


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convenient, nor efficient to have to recharge or change batteries constantly;
therefore a low power design must be considered.

Since the development of the Bluetooth technology took place in a Scandinavian
nation, it was only fitting for the developers to name their technology
breakthrough after a 10th century Danish King called Harald Bluetooth. King
Harald was remembered in Scandinavia for uniting Norway and Denmark, having
done this in a time in which great uneasiness was being felt, due to constant
battles between the different clans of the region. This proved to be a great selling
point for the developers of Bluetooth, since one of their slogans was that it could
be performed to unite devices across a number of platforms, such as the devices
at hand (sensors, remote control).

In September, 1998. The Special Interest Group (SIG) adopted the name
Bluetooth. The actual Bluetooth technology was developed in 1994 by Jaap
Haartsen and Sven Mattisson who were working with Ericsson Mobile Platforms.
SIG is responsible for not just the naming brand; it is also responsible for the
future success of the technology. Unlike Ericsson Mobile Platforms, SIG is not to
be considered a single entity; it is administered by a group of organizations that
include Ericsson, Microsoft, IBM, Intel, Agere, Motorola, Nokia, Toshiba, and
hundreds of other companies.

The Bluetooth technology is today still considered to be a fairly new technology;
the world is witnessing just the beginning of its potential in the user’s everyday
lives. Considering the basic facts; Bluetooth is a wireless technology that
specializes in short range transmission, causing less power consumption
needed. It has a signal improvement and it reduces significantly the risk of
interfering signals that share the same frequency band. The idea of the Bluetooth
is that it will replace the cables, with an expanded field of operations to mobile
accessories and healthcare, connecting portable electronic devices like cell
phones, laptops and iPods. The RF transceiver, protocol stack and base band
are some of the main components.

The RF (Radio Frequency) technology that Bluetooth operates on emits a series
of radio waves in a particular distance in order to communicate with other
devices. A transmitter oscillates at a given frequency, meaning that there is a
direct relationship between the speed of the oscillation and the height of the
frequency. If the receiver and transmitter stay tuned at the same specific
frequency, communication may take place between the devices. The radio waves
are used because they allow for transmission to occur through obstacles on the
way or even through a wall. In comparison with other technologies like the
infrared, the Bluetooth does not need to be within the line-of-sight for
communication to occur, allowing versatility with the implementation of
technology.




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Bluetooth technology also provides fast, secure voice and data transmissions.
The range for connectivity is up to 10 meters, it functions even in noisy radio
environments, ensuring audible voice transmissions in severe conditions, it
protects data by using error-correction methods, it provides a high transmission
rate and it encrypts and authenticates for privacy. Bluetooth provides two error-
correction mechanisms; there is the FEC (forward error correction) and ARQ
(automatic repeat request). It is usually applied to voice traffic when the accuracy
mechanisms used for data applications come second to the time of delivery.

Bluetooth has to compete with other signals found in a typical house, like
microwave ovens and garage doors. Synchronization of the network had to be
specifically synchronized to a particular frequency pattern. The Bluetooth network
moves through 1600 different frequencies per second, and the pattern is unique
to each network. The necessary configuration to form a bridge between
Bluetooth devices is the link manager software. It is located at the bottom of the
protocol stack. The link manager detects the software inside other devices, it
communicates with them using the link manager protocol. The link manager
accesses the Bluetooth hardware, the link controller, which is in charge of
sending and receiving data. The Human Interface Devices (HIDs) are product
enhancements to the Bluetooth software. They are specifically targeted to the
more private electronics such as home entertainment systems, personal
computers, stereos, etc. It would work in a scenario in which you have a main
desktop computer; this computer would contain one HID. The computer would
connect to other computers, or several HIDs would have to be connected to a
main computer. This technology could prove to be very useful in a future update
for the smart house idea, a stronger web of connections with miniscule loss of
data would be paramount, if there was a need to create connections with the
more private electronics mentioned before.

The transmission speed of the wired technology is still much faster than the one
used in the RF technology, however the radio frequency gives the customer the
option of a cable-less house. The combination of the 802.11 wireless networks
and the Bluetooth technology allow a plethora of implementations.

Bluetooth has undergone a series of updates and enhancements, making it
perhaps the most prominent brand, when it comes to wireless communications.
After their 1.0 and 1.0B versions struggled to survive, the 1.1 standard versions
provided a second breathing and reinvigorated Bluetooth. Then came the 1.2
version which made it possible to have a backward compatible connection, it also
made the detection of wireless signals and its connection a lot faster than in the
previous versions. It was also seen, that the Adaptive Frequency-Hopping (AFH)
had seen some improvements as well, reducing signal interference in a noisy
environment (this is what prevented interruption with similar technologies that
share the same frequency band). The introduction of an Extended Synchronous
Connection Oriented (eSCO) link type, allowing Bluetooth devices to monitor and
retransmit voice packets to improve the quality of the link. This being an

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important breakthrough in wireless devices that transmit audio data. This could
prove beneficial for the project; it gives leads the possibility for future
improvements by giving the option of making the Smart House compatible to
voice commands, without interfering with other electronic devices that use
Bluetooth as well.

In 2004, Bluetooth launched the 2.0 version boosting their previous 721 kilobit
per second transmission speed with and Enhanced Data Rate (EDR), almost
tripling its speed. With this new version, not only the speed was addressed, an
increase in the battery life time was also improved. With the power efficiency and
the speed, SIG answered two of the biggest marketing questions, thus the
popularity of the Bluetooth among consumers sky rocketed. The current 2.1
version holds secure simple pairing; sniff subrating, Encryption Pause Resume
(EPR) and an Extended Inquiry Response (EIR).

Secure simple pairing reduces the time it takes the pairing process; it also adds
more security without the need to add more tasks from the user. The sniff
subrating is an enhancement created for prolonged battery life per charge, this
will come into play when two or more devices search for other devices to connect
with. This is done by reducing the time intervals between the searches. With this
improvement, SIG achieved increased battery lives to triple what they were
before. The Encryption Pause Resume (EPR) gives better protection; this is done
by using a refresh for the encryption key, this gives stronger encryption and
longer connection hours. The Extended Inquiry Response (EIR) was made to
address the problem of coming up with a way to reduce latency and a fast signal
discovery, allowing for more specific information to be gained during an inquiry
stage, this was done to attack the problem of having long time for the connection
process.

More recently, it has been observed that an attempt to increase the relevance of
Bluetooth technology by wanting to merge with Ultra Wide-Band (UWB). This is a
technology that specializes on high-speed interconnections throughout devices.
The UWB was designed for short-range, wireless personal area networks
(WPANs) and doing all its usual processes with the lowest possible amount of
power. Because of its short-range radio technology, a wide variety of long range
technologies with a cellular wide area communications. Its legally operating
anywhere from 3.1 GHz to 10.6 GHz, with a power of -41dBm/MHz, it is thanks to
this that limits interference.

With that move in mind, the people of SIG are increasing speed of wireless
technology, allowing for video streaming with the lowest possible cost. This could
be tied to the project as a way of looking for future add-on technologies to the
original idea. With this there can be development in security video recognition of
the inside the house, which could be turned on before the user leaves the house.




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Section 5.2 - Different Approaches to Wireless
Interface
There are other approaches that can be implemented within the project to
implement a wireless interface other than Bluetooth. This section will explore the
protocols used in many other wireless systems and will discuss the benefits and
disadvantages to using such systems with the project.

Subsection 5.2.a - Wi-Fi 802.11
The Wi-Fi is another wireless connection. This technology is usually used to
connect computers to the internet, which requires very high speed connections.
The connection speed of the Wi-Fi ranges from 11Mbps to 200Mbps depending
on the protocol implemented. Another perk of this technology is its wide range for
a connection, giving the user more freedom to walk around away from the house
and still have a constant connection with the house. The user really has to pay
for all those great sounding specs, literally. This is very costly and in occasions it
could be frustrating to set up. Putting the original cost aside, Wi-Fi requires large
quantities of power to operate, this is usually attributed to the access points it
offers. This is not really an issue for the typical Wi-Fi connections in a household,
since they are connected to electrical plug-ins. For the ones that use it in a
mobile setting, the power consumption is a considerable problem.

The 802.11a standard runs at a speed of 54 Mb, with a frequency of 5GHz, using
an Orthogonal Frequency Division Multiplexer. The 802.11h however, has a
smaller frequency of 2.4 GHz. Wi-Fi operates within twelve channels that use
overlapping frequencies (except channels one, six and eleven that do not
overlap). The 802.11b/g/n formats are the most common versions used by the
iPhone4. With an 802.11n with a 2.4GHz only. Any of these formats can be used
as a way for communication if the project is ever updated to work on the iPhone
platform.

Subsection 5.2.b - Zigbee
Zigbee is definitely a possibility because of the advantages of a secure
communications technology, with a relatively low-cost, low-power, low data, short
range transmission. Its low cost makes Zigbee incredibly popular among
monitoring applications, making it a great fit for the project (simplified protocol
and limited functionality). That is exactly what is necessary for the project with a
low cost because it is essential for the limited budget. Low power makes it a
great fit for the Green part of the project, with smaller batteries and longer battery
lives. The low data is not an issue because the transmitting fairly simple basic
signals with the sensors and timers. The short range might prove to be a bit of a
problem, if expansion of the area is necessary to a much bigger house or space,
although it could be fixed by making a connection with a stronger technology,

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making it highly reliable. Their inability to perform Powerline networking is not an
issue either, since Zigbee was developed with the intention of interfacing for
smart appliance and metering purposes. In other words, Zigbee almost seems to
have been invented for the specific project.

Within the original intentions for the project, temperature, light and even security
programming was to be monitored the house and act according to the user's
commands. The implementation of the project is not only being intended for
houses, but for industry and health systems. This is achievable using Zigbee
because as a product, its priority is to be a viable solution for areas with high
levels of noise. It does this (finding the most appropriate channel through energy
detention and clear channel assessment and selection) and switching to it in
order to prevent noise interference.

Data integrity is also a very important requirement in the security area. The group
was studying the possibility of offering the technology efforts to have a security
system tied to the Smart/Green House project. The destination device
guarantees that the packet was received, allowing for data integrity. There are
certain devices that make Zigbee similar to a wireless network topology. The
coordinator which connects with other coordinates in different networks to make
a link with. This is done by saving certain information about different networks; it
can also be used for security purposes. Its end devices possess low memory
with the intention of conserve energy, therefore it is only turned on under specific
necessary circumstances (it goes to a hibernate-type state when is not needed).
The other device is really simple, the router trades information with other
connecting devices. Figure 5.1 shows the Zigbee unit that could be implemented
with respect to the wireless communications aspects of the project which will in
turn be used for data communication at low data transfer speeds and therefore at
inexpensive costs.




              Figure 5.1: Figure shows the Zigbee component to be used.
                 (Permission pending [thesiliconhorizon.com] site [12])




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Section 5.3 - Cellular Phone Connection to Smart
Greenhouse
There is a necessity to have a connection between the main house controller and
the internet. The internet connection is necessary because a connection between
the house and a smart phone, this way there is control to the smart house from a
distance (i.e. set up the AC at certain temperature) to accommodate the user’s
life style.

The two main platforms for smart phones that will be examined are the iPhone
and the Droid platforms. They are the two most popular platforms in the United
States of America so it would be wise to focus on one of these two, for marketing
reasons.

Subsection 5.3.a - iPhone
The iPhone has been a revelation in the public telecommunication world, now
considered to be the undisputed king of smart phones. Recently, Apple in an
effort to promote third party application development, opened to the market their
software developers kit (SDK). They also declared that the company wanted to
aid the distribution of other parties by creating the AppStore, this would give
consumers the option to search and buy the newly created applications, very
similar to the way they did with their iTunes online store. The iPhone uses an
operating system and presentation that are very accessible and easy to use, so
much so that it has set the standard for their competitors' operating systems.
Apple has more of a closed system, they not only have final say in what
applications to be placed in its AppStore, and it also disallows the development
of software that would modify or even compete with the already existing
applications (i.e. safari). Apple blocks the usage of other applications
frameworks, Java being among them as stipulated in their SDK contract. The
user is not allowed to put a new software language on the phone, or even open
it. The iPhone uses a mobile variation of the Mac OS X; it uses Objective-C as its
main programming language. It would be great if the iPhone would open up to C,
since some of the best developers like to program in C++.

Subsection 5.3.b - Android
The android technology was announced in late 2007. Google declared they were
developing the android technology in order to spur innovation among developers,
creating applications for mobile phones being the primarily reason. This
technology promised not to be exclusive to particular devices or carriers (the
iPhone was). While the android was an open source mobile platform (creating
freedom for third-party developers), apple developers had to unlock their phones
in order to create and distribute their own applications. The android "is a
completely open system... it is like working on a small box. It is a nice box that

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has a lot of features, but as a developer, you're a little constrained" said Jason
Cline, a senior software engineer at Web application developer Sitepen. Android
uses a Linux platform, using Java as its main programming language, giving
them the upper hand since Java is a more popular programming language. It is
because of this, that android is expected to be used on a wider range of devices,
with different customized features, keyboards and screen sizes. This makes it
necessary for android developers to edit their designs a bit in order to fit in with
other products. If Google manages to develop a programming language and a
platform to function the same way for different devices, it will ultimately decrease
the programmers' work before they can place their products on the market.

Section 5.4 – Comparisons of Technologies
The requirements of the Smart/Green house project are that the information gets
transmitted through the electrical components in the house into the main control
device. Speed is not as important as in other scenarios, but it still is important to
have a fast communication in case an urgent message needs to be transmitted,
or if a live feedback (from the plant for example) is needed. The distance at
which the device operates is important since the dimensions of the house are
unknown; the more distance there is to operate the better it will be when it comes
to dealing with the dimensions of the specific house. The cost and power
requirements are very important for making a decision, as it is stated in the name
of the project, the house is expected to not only be cost efficient, but to be power
efficient. It is important to look for the cheapest possible product, with the least
amount of power consumption that will meet the criteria for the project.

Technology Application             Maximum Power          Transmission Cost
                                   Distance (mW)          Speed (Mbps) ($)
                                   (m)

Ethernet      Short distance,   1-100m    ----            10-1000Mbps      $3-
              high speed                                                   $49.99
              communication
Bluetooth     Cable             10 m      Low             1-3 Mbps         $3
              replacement/Short
              range
              transmission
Wi-           High speed        50 – 67 m High            11-200 Mbps      $5-
Fi(802.11)    communication                                                $20

Zigbee        Short range          25 m        Low        0.03 Mbps        $2
              transmission with
              less throughput
              needs
              Figure 5.2: Comparing different communication technology

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As shown in the table above, different technologies have been compared in order
to find the one that best suits the purpose of the project. The first technology that
was discussed was the use of Ethernet cables. Ethernet offers the project very
low power consumption; this technology does not need a power supply of its own
like the other wireless technologies, making it very appealing from the power
efficient point of view. The Ethernet cable technology offers a long range to
operate, however this range obviously does depend on the length of a cable,
from a house point of view, the house cannot have too many cables coming in or
out of a single position, especially when the components that will be used are
expected to be small.

Despite its information transfer rate and economic flexibility, the Ethernet
technology will not be used because the project does not require such a great
information transfer rate, but most importantly because no house would
realistically have so many cables lying around. In case one of the cables needs
to be replaced, it would be very inconvenient to have to go through cable after
cable until the one that needs to be repaired is found.

The next technology is the Bluetooth; this technology was made for short range
transmissions of approximately 10 meters, low power but great transmission
speed and a cheap price. The range of 10 meters will not work for the project
because a regular house or apartment's dimensions would require at least
double that range. The low power requirement however, is a great thing for the
project since batteries will not need to be replaced as often as with other wireless
communication systems. The transmission speed is of more speed than required
by the project, though it may not necessarily be a good thing to have the extra
transmission speed; it certainly cannot hurt the project. The cost is very good for
the speed transmission, but the biggest defect of the Bluetooth technology has to
be the distance at which it operates.

The Wi-Fi technology was made for high speed communication and internet
connections. It has by far the longest distance of operation, between fifty to sixty-
seven meters, making it very appealing for communications between relatively
long distance in a house; unfortunately this great distance will not be needed
since the project will be implemented for houses of much smaller dimensions (67
m is close to the length of a football field). Its power consumption is high
compared to the other wireless communications, making it a bit harder for the
technology to be a good fit for the project. The transmission speed ranges from
eleven to two-hundred Mbps, this is a huge difference from the other wireless
technologies, unfortunately most of that transmission speed will not be used at
all, and the project does not send videos or any other heavily loaded
transmissions.

The price varies a lot from five to twenty dollars, although it is still cost efficient, it
is the most expensive of the wireless technologies. Overall Wi-Fi is a great
technology, but it will not be used in the project.

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Finally, there is Zigbee, a technology developed for short range transmissions
less throughput needs than other technologies. The maximum distance at which
operates is twenty-five meters, it requires low power to operate, its price is the
lowest one of the reviewed options, but its transmission speed is also the lowest
one with only 0.03 Mbps. Its transmission distance is perfect for the project; with
a good positioning the whole plant of the house can be covered. Low power
consumption and low price makes Zigbee the most appealing option. Seeing how
it was developed for remote controls like home monitoring, and smoke detectors
(among other things) that send very simple pieces of information to a central
control, Zigbee looks as if it will fit in perfectly in the project.

Section 6 - System Security
Security and system integrity are important for the project because as with other
communications, it is subject to hackers and external individual's attempts to
break in.

Subsection 6.1 - Security Issues for LANs
Perhaps one of the main characteristics of the LAN is its limitation scope; it is
because of this limitation that is usually seen in LAN units being used at home
connections between computers and office buildings. As long as there are no
connections with the outside world, LANs have very few security risks. However
few the risks may be, there are still very real security issues that could take
place.

If there is an open connection between the internet and the LAN, which was a
possibility being considered in order to control the house from a remote location,
using a computer with an internet connection is possible. Without the proper
precautions, there would be vulnerability to pretty much anyone with Internet
access through the link with the Internet provider.

If there were a dial-in access implemented to allow more than one user to
connect from a remote location, there could be some harm by the same
connection that allows more users to connect with the house. This same
connection could be used by others, making it necessary for the implementation
for safeguards.

With the connection and accessibility to the Smart Greenhouse, the possibility of
every user of the system is that they get unrestricted access. This also applies to
protecting the integrity of the system inside the network. Unauthorized internal or
external users could have the possibility to delete or change information that
could jeopardize the whole process of operations. [8]


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Subsection 6.2 - Security Issues for WANs
WAN and LAN security issues are quite similar, but it all depends on the way the
WAN is set up. If a private dial-up connection is used, the only security concern
would be if an individual taps the line or if he/she dials in pretending to be an
authorized user.

In the case of the project, it is very feasible to use secure options like Virtual
Private Networking (VPN) in order to have a connection that brings all LANs
together.

Perhaps the best way to protect the integrity of the communication system in the
house would be to implement a firewall. Firewalls are pieces of software running
on the access point of the network; it protects the information and resources
inside against intrusions from outside networks.

Subsection 6.3 - Encryption
There is awareness that with today's technology, it is fairly simple to intercept
internet communications, as long as there is enough range for the signal. The
best way to prevent what is known as "packet sniffing" or "traffic sniffing," is to
encrypt your information. This does not mean that your information will not be
accessed necessarily, because encryption systems can be broken. Breaking an
encrypted system is not an easy thing, it costs money and time, and the breaker
depends on finding an error in the engineering of the encryption.

Encryption is a process of transforming or hiding information, this is done by
using an algorithm, and the algorithm makes the information impossible to read.
The only way to access the information is with a key.

Section 7 - Project Management Research
and Design
In order to better serve the project's efficiency and functionality, it was decided to
implement a well working integration process as described in the Capability
Maturity Model Integration (CMMI). On their paper, Larsson, Crnkovic and Ekdhal
discuss the best practices in product integrations. They discuss the weaknesses
during the development process, emphasizing that these weaknesses are usually
found too late into the implementation, making them especially costly to deal
with. It is mentioned how specific technologies can possibly help improve the
integration performance, as long as they have the proper input.

With a component-based approach the development process changes which
may help with performing, depending on the expectations. By changing the

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development process, project's specifications can be tweaked such that there is
a more structured and organized set up.

Product integration usually takes part in the software development process. This
is the process where the problems come to surface, this typically happens in
large software projects, because the software parts are developed separately,
they are tested separately as well. Sometimes these problems remain
undetected until the products are integrated. This is a product of a lack of
coordination between phases or inadequately provided information. With the
addition of features and improvements, a breakdown of the entire system is
definitely possibility.

Product integration is defined in the article as, an integration of components into
a product that ensures the product's integrity before it can be delivered to the
customers in a timely manner. By definition, product integration is a way to be
time efficient, maximizing impact to the customer's specifications. There are three
objectives in the product integration process. They are as follows, (i) the product
integration should be prepared (ii) interface compatibility should be ensured (iii)
the product components should be assembled and delivered.

In the software system, component-based components are also found in runtime.
This makes it possible for the developer to make changes to the system without
having to make drastic changes, also making it possible to edit the system while
in operation. It is expected to see a simplification in the error correction and the
maintenance, also allowing for enhancements to be developed. Although this
sounds like a very good way to make necessary changes to be more efficient, it
is necessary to pay close attention when making changes to components
because it may be used by several other components. The most important
reasons why component-based approach improves the integration process are:
component specification, early integration requirements, standardized
interoperation and integration tool support. In the case of component
specification, a separation takes place because all interactions happen through
interfaces; in this case the separation is stronger than in an Object Oriented
approach. Although this process decreases architectural mismatches and
introduction of foreign properties, it also may cause other unforeseen issues.

Early integration requirements are implemented in order to show existing issues
that would otherwise be seen only during the final integration. Standardized
interoperation defines the standards of interconnection among components, thus
eliminating future architectural mismatches errors. Integration tool support is
inherited from CBSE making component-based technologies to be more
specialized, providing powerful integration tools. The group found that maybe not
all the approaches stipulated in the paper were necessarily good. By requiring
the interface descriptions to be complete, the developer could affect the design of
verification and validation of the components. This obviously poses a possible
communications issue; if the validations are changed the components might not

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be able to communicate with each other at all. This could cause considerable or
fatal holes in the implementation. It is important to acknowledge the pros of the
integration process described in the article. The confirmation of readiness for
integration, the design of the component is reviewed, tested and make sure the
interface descriptions are respected. The component selection is influenced by
the component-based approach. Requirement analysis turns collected need into
system requirements and investigation of compatibility issues among
components prevents communication issues.

Subsection 7.1 - Class Diagrams
For the Smart/Green House project, it was necessary to create a series of class
diagrams. The class diagram is basically a structure diagram in charge of
describing the structure of a given system, through the depiction of the system's
attributes, classes, methods and the relationships between all of the above.
Since class diagrams are considered to be a basic, but very important starting
point in any object oriented model. It was deemed necessary to incorporate a
class diagram describing the organization of the project. Figure 7.1 is the class
diagram developed for the project at hand; it shows several classes describing
the interactions, the inheritance hierarchy and methods.




   Figure 7.1: Class diagram describing the overall organization, classes, methods and
                                relationships to be used.

Figure 7.1 shows the interaction relationships between them, this will help the
group members have a better, clear idea of what the software organization and
structure will look like once it is done. As seen in Figure 7.1, there is an
inheritance hierarchy with the "USER" parent class. This class has two child
classes, "REGULAR" which is made to describe any regular Smart/Green House
user (i.e. visitor), and the "ADMINISTRATOR" describing the owner of the house,
or a user with the permission to alter and change all the "HOUSE" preset
schedules and procedures.



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The "USER" takes in both a login name and a password; this validates the user
to access the main controller of the house. This means that before any one user
can access the system, he or she must be registered in the system. A specific
username and password will be issued or chosen for every user. Once the user
is logged in, he or she can read the messages sent to the main house controller,
messages range from light-bulb failure to water nutrient alerts (messages will be
covered with GREEN and SMART house classes). The user can also regulate
the temperature of the house and lighting and power outlets for a limited time
(hours or a day maximum), if a permanent change is needed, the intervention of
an administrator user will be required. The administrator can change lighting,
power and irrigation schedules and distributions on a permanent basis.

The "HOUSE" class is also a parent class, like the "USER" class discussed
before. It has two child classes, "GREEN house" and "SMART house." The
"HOUSE" class has a code that identifies it, the user (previously discussed) could
control the overall power feed of the entire house, working in a similar fashion as
the power switches found in every house, the difference being that in this
situation, the user can shut down the power of the entire house with one
command, instead of flipping switches controlling different areas of the house. In
order to better serve the purpose of making the house energy efficient, it was
thought to send a report of the overall power consumption of the house (possibly
divided by zones) so the user can manage the energy consumption more
efficiently according to his/her needs.

As mentioned before, the "HOUSE" parent class subdivides into two child
classes. One of the child classes is the "SMART house" and it is broad objective
is to manage all the lighting in the house, the power consumption and the air
conditioning temperature. Some of the attributes describing this class, the lighting
in the house subdivided by zones. The house will be divided into different zones
(i.e. kitchen, living room, bedrooms, etc...), the objective of having this feature
available is to help automate the house further, an example of each scenario will
be provided later on in the report. The lighting will also be able to be adjusted
individually throughout the house. In the given case that a light bulb stops
working (or other related lighting problems), an alert message will be sent to the
user, informing him or her of the situation with the specific light, the message will
be displayed when the user signs in.

Another attribute of the "SMART house" class is the air temperature in the house.
This attribute will keep track of the house temperature throughout the day, this
information will be provided so the user knows when the temperature is the
highest or lowest, and program the A/C of the house accordingly. One of the
methods of the class will be to adjust the temperature. Adjusting the temperature
in the house can be done by all users, but only an administrator can program the
A/C to act on its own. The ability to read the power feed of the house individually
and by zones is another attribute in the "SMART house" class, just like with the
lighting of the house, this is done to help the user to better read the power

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consumption in the house and do the pertinent changes in order to be more
energy efficient. The power feed consumption of the house will be divided into
zones as well, it is not yet known how the zones will be divided because unlike
the lighting, there are a lot more power outlets throughout the house and to keep
track of every single one of them will not be efficient. In the given case of a power
failure, a message will be sent to the user, informing him of the problem when the
user signs in.

The other child class of the "HOUSE" class is the "GREEN house" class. This
class is necessary in order to take care of the "green" part of the project.
Basically, a specific plant will be taken care of, monitored and grown in the most
efficient, automatic way possible. This class will have three main attributes, the
most basic being the selection of the plant and storing information of the specific
treatments that plant will need. The database will hold the information describing
the plant (there could be more than one plant, but for testing purposes there will
only be one). After describing the plant, it is necessary for the database to store
the information about the lighting the plant needs in order to grow. The
information stored in this attribute could range from hours of lighting required to
positioning of the lighting; it is expected to have a method that takes care of the
lighting and other power requirements that could be made automatic. The other
two important attributes of this class are the watering needed for the plant and
the amount of nutrients required. Consequentially, two methods will be created to
measure the amount of water being pumped into the plant and if possible, to take
care of it by itself (this option is not confirmed at this point), it is also necessary to
have a method to take care of the measurements of the plant's nutrients, there
are several techniques to do this with simple measurements devices. It was a
good idea to add an extra method that would take care of alerting the user
through the main controller when the plant is not doing so well, when there is a
deficiency of nutrients, and also to tell the user when personal care of the plant is
due. The latter can be scheduled every X number of days.

The button interface for the house needed to have its own class called "BUTTON
INTERFACE," this class consists of two attributes that take care of the sensor's
inputs and outputs. This class is created to take care of the plant intended to
grow in the house. The access method is created to access the input and output
information recorded by the sensors on the plant.

Subsection 7.2 - Use Case Diagrams
The main purpose of use case diagrams is to present the functionality and
requirements of a system, using actors, associations, objectives, and
dependencies between them. In Figure 7.2, a use case diagram is used to
describe the usage requirements for the system used in the project.




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 Figure 7.2: Use Case Diagram representing the dependencies between a regular user, an
                       administrator (user) and a code developer.

In the figure is better described the differences and relations between three of the
actors in the project. The regular user, the code developer and the administrator
are all being described. The regular user has no unique characteristics, in this
project the regular user has a limited authority when it comes to interacting with
the house interface. Any user regardless of denomination is required to be
registered into the system with a user name and a password (the class specifics
will be discussed later), the first administrator accounts will be set up by the code
developers. The reason behind this is that the administrator's approval is
required before the creation of a new user is completed.

After the user's registration, the newly added user will be able to access the
program. The first thing the user will see after login will be a series of messages
describing the alerts sent in by the different components throughout the house,
the messages will vary from disconnection with one or more components in the
house or a broken light, to deficiencies in the plant(s) and the scheduled personal
maintenance checks. Consequently the user is expected to act in order to solve
the issues throughout the house. The regular user can manipulate the house
setting in a limited manner; he or she can change the ambient temperature in the
house, the lighting and the power distribution of the house, but only for a limited
period of time. In the case of the temperature, the user can increase or decrease
the central A/C, but these changes will be overridden by the scheduled
temperatures (for light and power changes as well). The regular user will also
have access to see the house status, schedules, etc. But will not have the ability
to edit anything on a permanent basis. The system will log the user off when it
detects no activity from the user after a small period of time (five minutes) or
when the user decides to at any point before the determined time is up.

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The administrator will be in charge of approving new users and the appointment
of new administrators, as well as deleting existing users. In case another
administrator needs to be deleted, the existing administrator will need to wait for
verification from the code/support team. Unlike the regular user, the administrator
will be able to shut down or power up the main power feed of the whole house
(like flipping the house power switches), the administrator can also create and/or
edit power, lighting, and plant maintenance schedules.

The code/support team is in charge of developing the software that controls the
house, as well as providing troubleshooting assistance with the software or
electrical components, and as discussed before their assistance will be required
when deleting existing administrators. Another use case diagram is used in figure
7.3, describing the relationships and actions of the house and the interface.




 Figure 7.3: Describes the actions and relationships between the house software and the
                                        interface.

As seen in the figure above, both the house software and the interface receive
and validate the login information, the user will insert his or her information into
the interface, the interface will then search through the data base and match the
information provided with the information stored, if there is a match the user will
be allowed to successfully log in, otherwise the user will be asked to try again or
to create a new account. The messages and alerts will be processed by the
house software and sent to the interface for the user to read. In order for the user
to log off successfully, a constant communication between the interface and the
software will be needed, a timer will be implemented in the software counting
down the minutes of no user interaction, when the timer hits zero, the software
will send information to the interface indicating that the user was logged off. In
case the user wants to log off on his or her own, the command will be sent from
the interface to the software, the software will process the command and return a

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    message to the interface informing it that the user was successfully logged off.
    The house will be programmed to run tests on the components throughout the
    house, on a regular basis (every few days) in order to make sure everything is
    running smoothly. The regulations of power and watering were already covered
    previously in the section.

    Subsection 7.3 - Software Design
    A simple way of defining software design for the project is to identify and execute
    the decisions on how the software developed will fulfill the project's requirements.
    It is important to make the following observation, the functions and tasks
    executed by the software program tend to be subject to editions and changes
    due to its volatility. Classes are used as the basis for structuring a system; this
    elevates continuity and reduces maintenance. A good software design should be
    able to serve as a tool for introduction to the project, for other group members
    and individual developers, describing project implementations. It should also
    serve as a way to show that there is the intention to meet the expectations
    described in the requirements.

    Subsection 7.4 - Simulation and Implementation
    The following section will show the main software architecture and logic. The
    program will be written mainly in Java.

    Subsection 7.4.a - Packages
    The reason behind creating a series of packages is to keep the code organized
    and clean. The sources will be divided into the following packages; each package
    will be responsible for a specific part of the code logic.

   Command.impl package: This package will contain the classes necessary to
    implement the command pattern
   Sensors package: This package will contain the classes in charge of all things
    related to the sensors, including the sensors themselves, actions by the sensors
    and other sensor related information (this package will contain sub-packages in
    order to help organize the different events and actions performed).
   Master package: This package will contain the main power feed operations of the
    house.
   View package: This package will contain the classes for the widgets that will be
    used to show the information to the user.
   Bridge package: This package will contain the classes that influence the view
    package classes and the Mediator Pattern. It will accept a series of events
    triggered by the view package classes and then it will flush these events into the
    wrap package.


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   Wrap package: This package will contain the classes in charge of executing use-
    cases (both the wrap and bridge packages will be further discussed later in the
    section under the mediator pattern implementation).
   Log package: This package will contain the Log4J extension class
   Init package: This package will contain the account login information for the
    users.
    The logic for the project was created in order to clearly differentiate the data
    display and the data processing parts.




                        Figure 7.4: Packets to be used by the program

    Subsection 7.4.b - Mediator Pattern Implementation
    At the beginning of the application, GUI components will be created (text fields,
    buttons, etc.) by the MainFrame. These components will be registered by the
    bridge package. A MediatorImpl.Java will be used for the Mediator Pattern.
    Figure 7.5 is a UML diagram used to show the relations between the widgets and
    the mediator.




     Figure 7.5: Class Diagram showing relations between implementation and the interface
                                           widgets.


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Figure 7.5 portraits the set up for the bridge package. The bridge methods are
basically divided into the register part which takes care of the implementation,
and the methods in charge to processing certain events.

The idea behind the methods and their associations with the Main frame
(JFrame), is to separate a piece of memory in charge of the setup for the
controlling of the different components of the house. It is also included a set of
buttons, they will take the user into different set of options (windows), walking the
user through the different features of the system.

Subsection 7.4.c - Sensors
For this application, the sensors are considered to be of utmost importance. In
order to add any kind of new sensors, and give the project a little more space to
work with, the following class hierarchy was made. The extensive support was
the main concern when dealing with this part of the project.




  Figure 7.6: Class hierarchy for the addition of new sensors and an organization of the
                                       existing ones.

Figure 7.6 is a depiction of how all the sensors should react to an impending
event (event as in turning on or off switches, etc). The organization shown in the
figure, gives the project members a lot of freedom, this will be the skeleton of
operations for the sensors in the house. In order to maintain a consistency in the
design, and give a simple implementation, the absSensor class is made. Making
it a matter of the absSensor class to be sub classed for the addition of a new
sensor.



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Subsection 7.4.d - Technical Specifications
The program's foundation will be discussed in this section. The program will be
written mainly in Java language. Java is a lot easier to program than other known
object oriented languages without having to sacrifice any of its power. This
language has a lot of similarities with C, C++, and objective C (same loop
syntax). A java program uses the java interpreter, which reads the byte code and
executes the instructions; this is implemented instead of natively executing the
program on the machine. Also, java eliminates the undefined and architecture
dependent constructs Java offers a wide range of built-in libraries that will prove
to be very important for the development of the code required for the project.
Java is not used for websites, although a possible implementation will be to make
it fully functional from a website. This will be taken more into consideration
depending on the viability of a Smart-Phone' application to run the program and
control the house from a considerable distance from the house. This may prove
to be the case depending upon time constraints.

The program will use JLabel and JTextFields for the pop up window greetings. It
will also be using these features for the subsequent windows in the program. All
the text fields in the display and the specifications of the program will be using
these as well.

JButton will be used for the choices given to the user after the sign in process
takes place. Each button will activate another segment or package of code,
depending on what the user is trying to do with the system. JButton will also be
used a lot through the program, since the idea of the code is to be kept as
simple, clean and easy to read as possible. Inheritance will be used for the
different parent and child classes that share the same characteristics. This will
mostly be used for the back-end of the software, although some implementations
will be seen in the front-end. Boolean expressions will be used for certain options
in the code. It is easier to use true or false Booleans for the light switches. The
system will measure if the light is getting any power being sent (the signals
between components will be of 0s and 1s), if the system returns a negative, the
software will assume that the light is off. In order to change it, the software will
send the component a signal that will change the 0 for the 1 and thus turning the
switch off or on. It is evident that if statements will be used a lot for this part of the
code.

As far as the login phase of the project. An array of memory space will be set to
the side for the pin code. Another set of memory will be set aside for the
username, but unlike the integer nature of the pin code, it will be expected to see
both integer and text fields ready for the username. For the validation of the user,
a database will be necessary to save the user information (username, password,
schedules, settings, etc). The information provided by the user when he/she is
attempting to login will be compared with the information existing in the database.
An if statement will be in charge to compare them two, if an exact match is met,

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the user will be granted access to the program, otherwise the user will be sent
back to the login page until he or she can make a successful sign in. In order to
keep things simple, the database will be separated into different aspects. One for
all the users and passwords, and the other for the individual actions of the user
and administrator. This will give access to the users to see the schedule created
by the administrator.

Approximately nine-hundred to a thousand lines of code will be necessary for the
creation of the program. These lines of code will be divided into a different set of
packages and classes. In order to keep the code as memory efficient as
possible, the use of abstract data types will be necessary. Multiset, queue, stack
and string will be the more popular types of data structures that are going to be
seen through the program.

Section 8 - System Walk-Through
The System will open up a window asking the user for his user name and
password, or the option to register if not already a user. The username is going
to be an array of values ranging from digits and letters only, and the password is
going to be a 4 digit pin. From the code perspective, this will be taken care of by
the log package, in the log package a new database will be created in order to
support the information provided by each user. When the user tries to sign in, the
system will compare the characters typed in by the user (the program will be
case sensitive), the system will match the arrays and when a perfect match have,
access will be granted, log4J is made specifically to validate login information in
an account.

Once the user is signed in, the system will recognize whether the user is an
administrator or a normal user and redirect him/her to the next page where a
greeting message will wait for the user, the message will contain the date, the
name of the user, a greeting message (i.e. Hello world) along with any other
important messages or alerts the system has thrown the user. This will be taken
care by creating a pop up window with the messages discussed inside of it. If the
user is an administrator, an extra message field will appear taking care of the
notifications about other users pending confirmations.

After the message is closed, the user will see another window with a series of
buttons, created for the different choices of use for the house. In the window will
be displayed three choices, a sign off button will be displayed, a choice to
interact and make momentary changes to the house option (labeled "My House
Now"), and an option to access the scheduled times for the house will be there
too. If the user is an administrator, he/she will have the option to click on another
button that will take the administrator to the security and validation part.

If the user chose to go to the "My House Now" option, the interface will take the
user to another window, in here the user will see option buttons to change the

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temperature of the house, the lighting of the house which will be divided into
zones or rooms in the house, and a status check button for the "green" part of
the project. If the user chooses to go to change the temperature of the house,
another window will appear with a table, in the table the "current" temperature will
be displayed in one field of the table, another field will contain the power
consumption of the A/C at that moment, another field will be blank with the
possibility of inserting a number between sixty-five and eighty-five, this number
will be sent to the system, the system will then adjust the A/C's power to adjust in
order to reach the desired temperature. The system will calculate the expected
power consumption of the A/C for the house to reach the desired temperature.

The option to change the lighting of the house will bring yet another window. In
this window, the outlay of the house will be displayed; it will show all the possible
lights once the user clicks on the desired zone he/she wants to influence. Once
that zone is clicked, all the lights in that specific room will be displayed by
position, as well as the power outlets. The user will be able to decide which of the
lights or power outlet is going to be turned on or off. The "plant status" button will
take the user into a window displaying the plant status, the scheduled watering,
lighting and scheduled maintenance. The current plant information will be
compared to the expected information for the plant at that one time. For example,
if the user has "X" plant that needs to be watered "X" amount of water, with "X"
time of light exposure a day, will be compared to the amount of water and light
that the plant is supposed to get for the day. The box will let the user know if the
current watering and lighting levels are within what is considered to be
acceptable for the specific plant.

Besides what has already been discussed before, the regular user will be able to
click on the "schedule" option. By clicking in this button, the system will open a
new window with a weekly view of the scheduled lighting by zones of the house;
each power component of the house will be identified with an identification code
composed of an array of three digits (i.e. 001 for the first component). The view
will be similar of a weekly schedule view for the classes at UCF. When the user
using the system is an administrator, after the greeting window, the main menu
window will look almost the same as the window for the regular user, except that
the administrator will need an extra window that will take him/her to different
page in the program. This other page will ask the administrator for the approval
of the upcoming user, the information displayed by the user will be displayed
(except for the password). Next to the name, the administrator will see two
options (Approve, Deny) for the requesting user; this will look very similar to an
average customer service questionnaire.

On the scheduled option for the house, the administrator the set schedules will
be shown like with the regular user, but the administrator can edit the schedules.
The administrator will have to click on a button named "edit." After clicking this
button, the administrator will have to choose from a specific date, or a set of
commands that will be the same for every day of the week. This will come in

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handy if the user or administrator knows he/she is coming home at a certain time
and wants the house lighting and temperature to be ready for when the user gets
home. As mentioned before, the scheduled temperature and light changes will
precede over the ones that are considered to be timed changes. In the given
situation where the user makes a change to the temperate at 70 degrees and the
scheduled temperature is to be set at 75 or 65 degrees, the scheduled
temperature will have priority over the other one. This will force the user to have
to log back in and make the changes again if he/she is dissatisfied with the
scheduled set. In the case of lights, the system will react in a simpler manner.
When there is a conflict between a scheduled light to be on, the system will
check if the light is on or not, if it is on, it will remain on. In the case the light was
previously turned off by a user, the schedule will take care of turning the light on.

Besides the options listed above. The administrator will have the opportunity to
shut down the entire system. This was implemented for the users who travel
away from home and want to save as much energy as possible in the house
while they are absent. This option will be found inside the schedule window, an
extra option will show up called "master control." This option will give the
administrator an extra way to control the house. The administrator will be able to
choose if he/she wants to shut down the power for the entire house including the
green aspect of the house, or if it should be done by the separate components of
the house (green vs. smart). Furthermore, it will give the administrator the
opportunity to shut down power to specific zones of the house. For the zones
aspect, the same window dividing the zones of the house will be displayed,
except this window will have the option to shut down the power of not individual
lights, but entire zones. The communication aspect of the project is important, it
is the bridge communicating the electrical components with the software and
therefore it was important to get all the specifications for the different products.
The products researched are the most popular; most used products that the
group could think of. It was important to compare the technologies discussed
previously because some technologies are more compatible with software
languages than others.

When it was time to think about a way to control the house from a remote
location, the first thing that popped in by the group was the usage of the Smart-
Phone technology to do so. The group members have different types of Smart-
Phones, so a consensus on which to use was determined by the availability to
the members and to the versatility of the phone programming. Unfortunately,
after all the research on the phones was done, the group realized that although it
would very nice and impressive to take the application into a Smart-Phone, it will
be very time consuming and unfortunately the group does not have a whole lot of
time to take its idea from a paper into practice. The "plan B" was to use a website
that would take care of controlling the house from a remote location, but it is not
as convenient as the use of a mobile phone. Besides, this option is also very time
consuming and the group is yet unsure on which of the options to go with.



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The software architecture was very helpful to the group. It gave every member a
better view of how to better organize the team into sub groups and delegate
different responsibilities to the members. Earlier in the report, a journal was
discussed on how to be efficient in the implementation of a project. This was
actually very helpful; it gave the group a glimpse on how important a strong
foundation and organization is for a group project.

As far as the class diagrams, it was good to see how some of the concepts
previously learned in software classes throughout the college career are actually
implemented and necessary for big scale projects. The organization of the
packets and the classes was also important because it gave the code developers
a better vision on how to write a code that will be easy to read and easy to
expand. The subdivision of the code into packets also gives the group the ability
to make changes to the code without having an overwhelming impact on the rest
of the program structure. Finally, it is necessary to mention. Working with
different people is very enjoyable, but very complex as well. It was under this
conditions that it was realized how important it is to have leaders in a group, and
how important communication is between the members of a project.

Section 9 – Administrative Information
This section will discuss the specifics of budget and finance information as well
as the timeline of the project. This will clarify the time and financial constraints in
the project as well as work allocation.

Subsection 9.1 – Time Allocation
This section will define the time constraints for the implementation of this project
as well as time management with respect to the work allocation. The time
constraints for this project will be around 3 months therefore most of the
prototyping period for the systems involved in the project will be conducted within
the first two months. In the prototyping phase of the project, tests will be
conducted to verify the functionality of all the systems. With the tests successful,
the actual prototypes are built into a final product and will be implemented
together and tested further to increase the reliability and sustainability of the
project. Figure 9.1 shows the first half of the milestone chart of the project, which
shows the tasks being conducted on the respected day. Figure 9.2 shows the
second half of the milestone chart of the project. This chart will show the tasks
that are needed for the progress of this project as well as estimating the time it
will take for each and every task. As can be seen by the milestone charts, the
start date of the project will be at May 01, 2011 whereas the end date will be July
27, 2011 leaving around 88 days to complete the project. The color of each task
in the milestone charts correspond to the group member that will be handling
those certain tasks.



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               Figure 9.1: First half of the Milestone Chart of the Project




              Figure 9.2: Second half of the Milestone Chart of the Project

Tasks labeled blue will be handled by Richee Ramsahoye, tasks in red will be
handled by Rafael Abreu, tasks in green will be handled by Kaltrin Gjini, and
tasks in yellow will be handle Danny Gonzalez. The final task in purple will be
handled by all members in the group, as this is the final task of putting the project
together.

Subsection 9.2 – Budget and Financing
The budget of this project is held at $420.00, as that was the determined
expense for each part of the project. The goal of this project was to have the
project implemented with inexpensive parts such that the cost will be low
therefore it was reasoned that a maximum of $100 was to be allocated to each
part therefore the entire project will have the total cost of $400.00. The extra $20
is reassurance if the budget gets exceeded. Since the budget is shared between
each part of the project, it is possible that one part of the project will use more
than another therefore as long as all of the cost is balanced to $420, the project
has met its goal. The financing of the project will be self-financed in which the
cost will be split between all members in the group. With the current design of the
system, the total cost of the materials comes to $287.97 with the central control

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unit consuming approximately $85.00, the wall unit consuming $18.30, the
growing system consuming $166.00, and the wireless unit consuming $19.00.
Figure 9.3 displays a table indicating the cost of the project with the prospective
components. As can be seen by the figure, the cost of all the components is
indeed selected for their inexpensiveness. There are however some unavoidable
expenses such as the cost of the solenoid valves because they are the most
expensive component on the list with respect to quantity. However, these
components are necessary for the functionality of the project and therefore must
be used. With this cost being determined to be $288.30, the prospective cost of
the project is only 68.6% of the budget therefore conforming to the specifications
of the project pertaining to the cost.

 System             Component               Quantity       Price Per Unit Cost
 Growing System     Water Tank                      1             $15.00   $15.00
                    Red LEDs                       50              $0.32   $16.00
                    Blue LEDs                      40              $0.65   $26.00
                    Solenoid Valves                 2             $25.00   $50.00
                    Spray Pump                      1             $35.00   $35.00

                    Pipes                           3            $0.40       $1.20
                    Mist Nozzles                    1            $5.79       $5.79
                    Clamps                          4            $2.00       $8.00
                    Net Pots                       20            $0.30       $6.00
                    Voltage Comparators             2            $0.14       $0.28
                    Operation Amplifiers            2            $0.88       $1.76
                    Diode Bridge                    1            $0.12       $0.12
                    Voltage Regulator               1            $0.56       $0.56
                                                               Subtotal:   $165.71
 Wall Unit          MSP430                             1         $4.30       $4.30
                    Development Kit
                    RF Transmitter                     1          $2.00      $2.00
                    C1101
                    MSP430AFE221PW                     1          $0.65      $0.65
                    ACS756 Hall Effect                 1          $6.35      $6.35
                    Sensor
                    Step Down                          1          $5.00      $5.00
                    Transformer
                                                               Subtotal:    $18.30
 Central Control    LCD Display                        1        $15.00      $15.00
 Unit
                    USB Cord                           1          $5.00      $5.00
                    USB Buffer                         1         $10.00     $10.00
                    Central Control Core               1         $15.00     $15.00
                    Counter                            1         $15.00     $15.00
                    Multiplexer and                    8          $0.62      $4.96


                                                                               122
                        Decoders
                        Buttons and                        1            $10.00    $10.00
                        Switches
                        Wires                              1           $10.00     $10.00
                                                                      Subtotal:   $84.96
 Wireless       Zigbee Unit                                1           $19.00     $19.00
 Communications
                                                                         Total:   287.97
                           Figure 9.3: Prospective Project Expenses


Section 10 – Appendix
Subsection 10.1 – References
2.1 - http://en.wikipedia.org/wiki/Aeroponics

2.1 - http://en.wikipedia.org/wiki/Hydroponics

2.2 - http://en.wikipedia.org/wiki/Grow_lights

3.1 – http://tlc.howstuffworks.com/home/smart-home.htm

3.1 – http://standby.lbl.gov/

3.2.a – http://www.energyefficientchoices.com/products/energy-savingsmartstrip.html

3.2.b – http://www.smarthome.com/2046/Programmable-Receptacle-Timer/p.aspx

3.3.a – http://www.smarthome.com/7008/Sensaphone-Web600-Web-Based-Monitoring-and-
         Alarm-Notification-System/p.aspx

3.3.a – http://www.smarthouse.com.au/Automation/Security_And_Intercoms/

3.3.a – https://www.adthomesecurity.com/family-
         package.aspx?se=google&keyword=adt%20home&match=broad&ecid=resipscid00
         1&scid=179018730&geo=national

3.3.b – http://www.thiscaringhome.org/products/voice-reminder-system.php

3.5.a – http://www.x10.com/technology1.htm

3.5.b – http://pulseworx.com/UPB_.htm

3.5.b – http://www.be-
         home.com.au/Parts/parts_content/upb%20products/UPB_overview.htm




                                                                                      123
3.5.c – http://www.one-
         net.info/index.php?option=com_content&view=category&layout=blog&id=16&Itemid
         =20

3.5.d – http://www.zen-sys.com/modules/iaCM-ZW-PR/readMore.php?id=16777216

3.5.d – http://www.z-wave.com/modules/xoopsfaq/index.php?cat_id=2#q32

3.5.d – http://www.zwaveworld.com/ask/ask8.php


3.5.e – http://www.dash7.org/index.php?option=com_content&view=article&id=9&Itemid=11

3.6.b – http://www.atmel.com/dyn/resources/prod_documents/doc2545.pdf

3.6.d – http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en010384

3.6.e – http://focus.ti.com/docs/prod/folders/print/msp430fe4252.html

3.7.b – http://dataweek.co.za/news.aspx?pklnewsid=11743

3.7.b – http://www.allegromicro.com/en/Products/Part_Numbers/0756/

3.7.b – http://multyremotes.com/ac-motor-speed-control.htm

3.7.b – http://zone.ni.com/devzone/cda/tut/p/id/8198

5.1.a – Communication networks, a concise introduction by Jean Walrand and Shyam
         Parekh page 28

5.1.b – http://blog.gisautomation.com/2009/07/bluetooth/

5.1.b – Bluetooth End to End by Dee Bakker, Diane McMichael Gilster, Ron Gilster

5.1.b – http://bluetomorrow.com

5.1.b – http://www.mydigitallife.com

5.2.a – http://apple.com

5.2.b – http://freescale.com

5.2.b – Network Security Fundamentals by Gert DeLaet and Gert Schauwers




                                                                                   124
Subsection 10.2 – Illustration Permissions
[1] Reprinted with Permission from hydroponiki.pbworks.com




[2] Reprinted with Permission from Aerofarms




[3] Permission Pending




                                                             125
[4] Reprinted Under Public Domain from Wikimedia Commons
       (http://en.wikipedia.org/wiki/File:Solenoid_Valve.png)




[5] Reprinted with Permission from Lawrence Berkeley National Laboratory




[6] Permission Pending




                                                                     126
[7] Reprinted under Use Restriction of Texas Instruments




[8] Permission Pending

[9] Reprinted with Permission from Maxim




                                                           127
[10] Reprinted with Permission from Display Elecktronik GmbH




[11] Reprinted with Permission NXP




[12] Permission Pending

                                                               128

								
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