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University of Illinois, Urbana-Champaign
ECE445 – Senior Design Lab
Spring 2006
Design Review:
Improved Class Participation Input Device
Ching Man Hui
Debi Misra
TA: Hyesun Park
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Improved Class Participation Input Device
I. Introduction
Recently, several professors at the University of Illinois, Urbana-Champaign (UIUC)
began to enforce student attendance and participation by implementing a wireless input
device system in their classes. It is a simple concept: professors ask a question, the
students then pick a choice using their input devices and the answer is recorded. If a
student answers a question correctly, he or she receives a point for participation.
However, the actual implementation of this system is not that simple. Currently, in a
certain course held at UIUC, an input device by Turning Technologies, called Response
Card RF, is used. The keypad contains 12 buttons labeled digits 0-9 (A-J), “Go” and “?”.
There is also one LED on the input device to signal successful transmission.
What inspired us to improve the class participation input device was the tremendous
confusion during the first few lectures of the semester. Due to the lack of a display on
the input device, students were not able to confirm that their input device:
1) worked properly,
2) was on the correct channel, and
3) sent the desired answer.
Students were also unable to confirm that their answer was received and recorded.
Our project aims to improve the current class participation input device by creating a
more user-friendly version. We believe that the improved input device will benefit
students and ease their anxiousness in submitting answers. It will also benefit professors
by not wasting valuable class time to set up the system and ensure that each student’s
input device works properly.
Objectives:
In order to demonstrate the effectiveness of our improved input device, we will create the
input device and the CPU. We will use 2 sets of the HP series transmitters/receivers to
complete this project. One set will be used to send data from the input device to the CPU.
One set will be used to send confirmation from the CPU to the input device.
For the input device, we will use 2 LEDs: an LED to confirm the signal has been sent and
an LED to confirm the answer has been received and recorded. We will also add an LCD
display to the input device to confirm channel and answer to be sent.
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Benefits:
Ensures the user that input device is on the correct channel
Allows user to confirm answer before submitting
Provides confirmation that the answer has been sent, received and recorded
Eases students’ fear of submitting the wrong answers
Eliminates confusion and reduces set-up time at the beginning of the semester
Features:
Portable
Wireless Input Device
16 Button Keypad, including digits 0-9 and letters A-D
An easy to read LCD to display channel and answer
Two LEDs for signal confirmation
Records answer in computer upon data transmission
Additional Features (time-permitting):
Input Device Identification
Battery Display
II. Design
Block Diagram:
Input Device
Power
LCD Supply
LED LED
PIC CPU
Number Pad Recorder
RF
Transmitter1 Receiver2
RF
Receiver1 Transmitter2
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Block Descriptions:
Our project contains two units: an input device and a CPU.
Input Device
The input device will contain 7 modules: a PIC, a number pad, an LCD, 2 LED’s, a
transmitter, and a receiver. This wireless device is used by students to enter, confirm and
send an answer, as well as to receive a signal for answer processing confirmation.
PIC
This module is the core of the input device and is linked to each of the 6 modules
using a microcontroller on a PCB. When students input their answers using the
number pad, this module registers the answer and displays it onto the LCD. After
students confirm the answer, the answer will be sent to the CPU by the transmitter,
and LED A will illuminate to confirm that the answer has been sent. Once the
CPU has recorded the answer, the receiver will obtain a signal to confirm that the
answer has been processed and recorded. The PIC registers this signal and the
LED B will illuminate to acknowledge the student of the confirmation.
Number Pad
Students will use this module to input their answers by pressing the buttons for
digits 0-9 or letters A-D. Students will also use the number pad to confirm their
answers by pressing the asterisk button or to request to re-enter their answers by
pressing the pound button.
LCD
This module will display the channel of the input device and the answer that a
student has entered by the use of the number pad.
LED A
This module will illuminate when the answer is confirmed and ready to send.
Transmitter1
The transmitter sends a signal (the answer) to the receiver of the CPU.
Receiver2
The receiver obtains a signal from the transmitter of the CPU to acknowledge that
the answer has been processed and recorded. Then the receiver sends a signal to
the PIC to illuminate LED B.
LED B
This module will illuminate after the PIC registers the signal obtained by the
receiver.
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CPU
The CPU contains 6 modules: 2 MAX232s, a receiver, a RS232 serial port, a recorder,
and a transmitter. This unit is used by the professor to receive and record students’
answers.
Receiver2
The receiver obtains a signal (the answer) from the transmitter of the input device
and sends the signal to the MAX232 chip, which outputs to the computer through
the RS232 cable.
Recorder
We will code the recorder to record the answer received from the RS232. After
the answer has been recorder, a high signal is sent back to the input device to
confirm as feedback. Thus, the recorder will send the signal to the transmitter
through the RS232.
Transmitter2
The transmitter sends a signal to the receiver of the input device to confirm that
the answer has been recorded.
Schematics & Flowchart:
The next 3 pages show our schematics and flowchart for the software. We will wire the
circuits on two protoboards: one for the input device and one for the CPU. We will
program the microcontroller on the input device and the recorder on the CPU to ensure
the proper function of our input device system.
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Input Device Schematic:
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CPU Schematic:
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Performance Requirements:
Our improved input device should meet the following performance requirements:
Illumination of LEDs to confirm data transmission
Less than 2 seconds response time for LEDs to illuminate
200 ft transmitting range
The input device will be simulated in a classroom environment. The student will use the
input device to submit their answers, and the professor will use the CPU unit to record
students’ answers. Improving feedback is one of our main goals, and the LEDs will
signal successful data transmission to the students. The response time should be less than
2 seconds to minimize confusion and anxiousness of students. A typical classroom
would be no longer than 200ft, thus the input device should meet the 200ft transmitting
range.
III. Verification
Testing Procedures:
As we complete various parts of the design, we will test each component separately to
validate that it functions on its own. The testing procedures for each component are
described below:
LCD
We have powered the LCD to ensure it would light up. We will adjust and send
the 8 bits of data from the PIC according to the character font codes on the data
sheet to ensure that digits 0-9 and letters A-D can be properly displayed. Later,
we will verify that the LCD is properly displaying the channel, as well as the
selected answer.
LEDs
We have tested that the LEDs properly illuminate when voltage is high. We will
test LED A to ensure that it illuminates after an answer has been confirmed and
ready to be sent. We will also test LED B to ensure that it illuminates after the
signal is received and recorded by the CPU.
CPU
If the transmitters and receivers are working properly, then the CPU should be
able to record the answer correctly as well. We will test the CPU by monitoring
the recorded answers.
Transmitters/receivers
First, we will test to ensure that we have set up the transmitters and receivers
correctly and that the signals are being sent and received as desired by inputting a
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square wave (from a function generator) and recording the output on the
oscilloscope.
We tested the RF network at a distance of 22 feet. Our results confirmed our set-
up and the functionality of transmitters/receivers:
DIAGRAM A
This is the inputted square wave sent form the function generator to the
transmitter on the input device. The top line represents a second channel that was
not connected for this particular test.
DIAGRAM B
This is the output of the receiver on the CPU side.
Once this works, we will test the different channels for the least noise. Upon
programming the PIC, we will test the range for the input device.
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Number Pad
We have tested the functionality of each of the 16 buttons on the number pad.
According to the data sheet, if any of pins1-4 is high while a button on the
number pad is pressed, one of pins 5-8 will be high depending on which button
has been pressed. Our results verified that every button on the number pad
functions correctly, as shown in the example below:
When button1 is pressed, when we send ‘high’ to pin1, pin5 is also ‘high’.
DIAGRAM C
This is the output of pin5.
DIAGRAM D
This is the output of pin6, which is ‘low’.
For testing purposes, we had limited our current and voltage. Later, we will test
the number pad again by programming the PIC to depict the button pressed and to
convert into the 8 bits to display onto the LCD. We can also confirm these 8 bits
are correctly registered by displaying the bits onto LEDs.
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After each component passes its function test, we will then test the input device system
by running through the entire process. We will use the input device to enter the answer.
This will re-confirm proper operation of the number pad and the LCD. We will then send
the answer after the LCD displays an answer confirmation. When the answer is sent, the
correct operation of the LEDs and the transmitters/receivers will be verified. Our goal is
for the user to input, confirm, and send an answer and for the CPU to properly record the
user’s input in less than 2 seconds. Our range will be tested through our tolerance
analysis below. In the end, we will simulate a classroom to test and verify that our input
device system meets our goal and performance requirements. A successful trial would
indicate that our PIC functions perfectly as well.
Tolerance Analysis:
Our input device will rely heavily on the wireless RF networks for both answer
submissions and feedback purposes. An important factor in a successful RF network is
the distance between the CPU and the input device. One of our performance
requirements is 200 ft range between the input device and the CPU. We will measure the
effectiveness of our input device at various distances in a classroom. From our results we
will analyze and determine the maximum distance between the input device and the CPU
that still allows for proper operation.
IEEE Code of Ethics
We are new partners for this project, so our strengths and weaknesses regarding
equipment usage and EE knowledge differ. In accordance to the IEEE Code of Ethics,
we will work together as a team and support each other in making our project successful.
We will admit our mistakes and seek help and criticism of our work. We will also credit
contributions to others who have helped us. One of our goals for this project is to learn
additional technical skills and technology applications. Finally, since our input device is
already on the market, we will ensure that our input device is unique.
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IV. Cost and Schedule
Cost Analysis:
Labor
Ching Man Hui ($50/hr) x 2.5 x 100 hrs $12,500
Debi Misra ($50/hr) x 2.5 x 100 hrs $12,500
Estimated Labor Total $25,000
Equipment
Description Part Number Quantity Price ea. Total Price
Wireless RF Transmitters Linx HP Series 2 $24.10 $48.20
Wireless RF Receivers Linx HP Series 2 $32.20 $64.40
Antennas/cables 4 $4.61 $18.44
32 characters *2 lines LCD Shelly 1 $5.00 $5.00
LEDs 2 $.20 $.40
6” by 9” Protoboard 2 $100 $200
Number pad 96BB2-006-R 1 $12.87 $12.87
Microcontroller PIC16F877A 1 $9.95 $9.95
Driver/Receiver MAX232 2 $1.55 $3.10
Serial Port Cable RS232 1 $12 $12
20MHz Crystal Oscillator 1 $1.50 $1.50
Miscellaneous (wires, resistors, capacitors, soldering materials, etc) $10
Estimated Equipment Total $385.86
Estimated Total Costs (Labor + Parts) $25,385.86
Parts Status:
We had received many of our parts through the TA and the Parts Shop. We have all our
parts except for the RS232 cable.
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Schedule:
We will hold a weekly meeting with our TA to discuss our progress. The following table
lists our project goals for the upcoming weeks.
Week of: Ching Man Hui Debi Misra
2/13 Research transmitters Research receivers
2/20 Test the functionality of number Test the transmitter/receiver
pad, LEDs, and LCD networks; wire the circuits
2/27 Research PIC Research recording in CPU
3/6 Program PIC in Input Device to
Program recorder in CPU to
receiver data from number pad and
3/13 receiver data from Input Device and
to send through the RF network to
record the data onto the computer
the recorder in CPU
3/20 Spring Break
3/27 Program PIC to add LCD and LEDs
4/3 Debug & Final Tests
4/24 Demo & Presentation
5/1 Turn in Final Paper & Lab Notebooks/Check-out
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