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AVR MY EXPERIENCE IN PROGRAMMING AVR MICROCONTROLLER

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AVR MY EXPERIENCE IN PROGRAMMING AVR MICROCONTROLLER Powered By Docstoc
					MY EXPERIENCE IN PROGRAMMING AVR MICROCONTROLLER USING
                     WINAVR/AVRGCC

                                by

                                         BIBIN JOHN




                         Digitally
                         signed by
                         Bibin John



                 Bibin   DN: cn=Bibin
                         John, c=IN
                         Date:
                         2006.04.28
                         11:08:52 Z
                         Reason: I am



                 John
                         the author of
                         this document
                         Location:
      Signatu            Ernakulam
      re Not
      Verified
                                       NOTICE

                                        This book is for newbies for programming AVR
microcontroller using WinAVR. This is mainly for those who want to make robots
using Atmel's AVR.Here i am writing this because I want to include troubleshooting
tips and simple working examples for newbies. The main reason for choosing AVR
microcontroller is because of its facilities and support from Linux compilers and cheap
cost programmers. Here i am using WinAVR and BSD AVRDUDE programmer. All
the codes in this book are tested with WinAVR2006. Before starting this you should
read my other books(it will be good) because I refer to that books for some parts.All
books are available on yahoo group-booksbybibin

                                     I thank my teachers of MNNIT and my
colleagues Anil K.M,O.Praveen Kumar Reddy, M. Satish,Vigith Maurice, J
Rajashekhar Reddy,Athul Sona,Sanjo Sebastin . So i feel this book can guide you
through troubleshooting AVR microcontrollers. I thank my teachers of THSS Muttom,
Thodupuzha from where i learned the very basics of electronics.If you find any
problems put a post in yahoo groupbooksbybibin.
                               I am providing this book free of cost. You can use this
book as a study material. I don't want my book to be used as a material for business
without my permission. You are not allowed to upload this book in any other sites.

                                                              BIBIN JOHN
e-mail:njbibin@yahoo.co.in
website:www.geocities.com/njbibin
forums for AVR microcontrollers:
www.avrfreaks.net
www.avrbeginners.net
Www.roboticsindia.net
www.edaboard.com
Yahoo group:
avrclub
avrbooks
magazine:Circuit Cellar
                                                                INDEX

Why AVR???..................................................................................................5
As a beginner what i need to know???....................................................5
Softwares Required.....................................................................................5
Hardwares Required...................................................................................5
Difference between atmega32 and atmega32L.......................................5
GETTING STARTED.................................................................................6
LET'S START...............................................................................................6
Makefile.........................................................................................................9
What you had done in first program??...................................................15
PROGRAMMER HARDWARE...............................................................15
COMMON ERRORS IN AVR PROGRAMMING..............................20
TROUBLESHOOTING.............................................................................21
MOST IMPORTANT TIP.........................................................................22
FUSE BITS..................................................................................................24
SETTINGS FOR EXTERNAL CRYSTAL AND JTAG DISABLE.....26
IMPORTANT NOTES ON FUSE BITS..................................................27
DISABLING JTAG................................................................................27
DISABLING JTAG AND USING INTERNAL 8Mhz CLOCK..........29
INTERFACING LCD WITH AVR...........................................................30
SOME IMPORTANT COMMANDS USED
FOR PROGRAMMING.............................................................................34
L293D INTERFACING WITH AVR........................................................35
BIPOLAR STEPPER MOTOR DRIVING USING AVR.....................38
UNIPOLAR STEPPER MOTOR INTERFACING................................41
KEY ENCODER INTERFACING(74922)................................................43
7-SEGMENT DISPLAY INTERFACING WITH AVR.........................46
MULTIPLEXED 7-SEGMENT DISPLAYS.............................................48
IC TESTER....................................................................................................49
UART of AVR..............................................................................................51
     Troubleshooting...............................................................................51
SERIAL PORT OF COMPUTER..............................................................52
BIOS SETTINGS.........................................................................................53
SERIAL PORT INTERFACING WITH COMPUTER..........................54
HYPER TERMINAL................................................................................58
Device Manage COM Properties..........................................................60
Testing your computer Serial Port................................................61
SERIAL PORT TROUBLESHOOTING AND ERRORS..................62
SERIAL PORT with LCD DISPLAY....................................................65
INTERNAL ADC OF AVR....................................................................69
ADC with SERIAL PORT and LCD.....................................................71
       TROUBLESHOOTING................................................................73
TIMERS......................................................................................................74
which one should I choose Atmega32 or Atmega32l.........................74
IMPORTANT THINGS FOR TROUBLESHOOTING.....................75
links.............................................................................................................76
Why AVR??????
AVR microcontrollers are popular because of their Linux support and their softwares
like AVRGCC and AVRDUDE. If you start learning with any microcontroller the cost
you have to pay is the microcontroller cost+software+programmer. If you compute
this then AVR is the best. Atmega8 is available with Rs.75 and programmer cost is just
a printer cable costs Rs.40 with some wires and AVRGCC for Linux and WinaVR2006
for Windows.It has facilities like inbuilt ADC which is not there in 8051, which will be
advantageous for robotics. Software are easily available for other microcontrollers but
they have a limit of maximum 2K program memory. The project 'embedded ethernet'
have around 10K program memory usage while WinAVR have no such limitations.
The programmer cost of 8051 and pic are above Rs.400(as far as I know). See
http://www.electricstuff.co.uk/picvsavr.html
As a beginner what i need to know???
Here I am going to talk about microcontroller just like a computer running on parallel
port and a C program. I am using the same examples. Basic thing you have to know
how to program the chip and writing programms for the chip. If you know 8085 then
it will be easy to understand. Anyway I am writing codes in C so that it will be easy to
understand.

Softwares Required:

WinAVR2006,AVRDUDE(if you are using AVRStudio)
www.winavr.sourceforge.net

atmega32,atmega8 datasheet(see in atmel.com)
You better make logins in www.avrfreaks.net so that when you have doubt, you can
put it there.

Hardwares Required:
atmega32 or atmega 8 (atmega32 costs from Rs.200 to Rs.350 and atmega8 from Rs.75
to Rs.120)
Breadboard
Printer Port cable
Serial port cable
Crystal(3.6864Mhz)
Difference between atmega32 and atmega32L:
Both are same only difference in frequency and voltage limitations. I prefer atmega32L
because of its low cost and easy availability. Atmega16 also serve same purpose except
its Flash is 16KB(sufficient) and difference in memory capacities. The remaining
hardware portion are same for both.
                                           5
                               GETTING STARTED

                                     First you should require a compiler which
converts your program into the hex code of the avr microcontroller. If you use C for
programming Avr then you can use WinAVR, CodeVision AVR, ImageCraft AVR,
BASCOM AVR for programming in BASIC, AVRStuidio for programming in
assembly. But here I am talking about C programming. I use WinaVR2006 for all these
programms compilation. Same code is valid for AVRGCC in Linux. Second
requirement is a programmer which transfers the . Hex code(machine code for AVR)
into the chip. That is a programmer which burns the chip. I use BSD programmer for
that.


                                   LET'S START

                                           Install WinaVR2006 to C drive. Then you
can see that your desktop has the following programs.




The main program we use is the programers Notepad. So let's start with first program.


                                         6
7
Let's start with first program of blinking LED's on all ports
Open Programmer's Notepad and type the program in
Folder:blink
progrm:bibin.c




Store it in a folder named blink. How to compile it ? Go to Tool->Make.
> "make.exe" all
make.exe: *** No rule to make target `all'. Stop.
> Process Exit Code: 2
> Time Taken: 00:00
                                            8
Now you have to create Makefile to compile the C program.
Open



and do the following




                                        9
10
11
Now save the Makefile in the folder where your program is. Better you use the
Makefile in the code I had given

Now open Makefile using Notepad and do the following.




                                         12
13
Here I made CPU frequency to 1Mhz because when you buy the chip, the default
frequency is 1MHz with JTAG enabled. They use internal RC oscillator to generate
1Mhz. I will explain more about it in fuse settings




                                        14
What you had done in first program??

See the datasheet what DDRA and PORTA represents. DDR determine the direction
of the specific pin and PORT register have the value which should be sent to the port.
So here we had written a program to blink LED's on all ports A,B,C,D. Next step is to
program the chip. So we had to use a programmer to load the program into the
microcontroller's flash. Here we are using BSD programmer with AVRDUDE software
as we have set in Makefile. If you are using a different programmer, then you have to
change the programmer options.

                           PROGRAMMER HARDWARE

Here we are using BSD programmer which is low cost about Rs.40(Parallel
Port cable+some wires).See the following link
www.bsdhome.com/avrdude
I just redrawn it here. You buy a centronics printer cable which cost about Rs.40




This is valid for all microcontrollers of AVR which are supported by AVRDUDE
programmer. See how to do it for atmega32


                                          15
See my programmer.




                     16
17
Instead of using Vcc of supply you can use any pin on the data port(D0) for Vcc of
AVR.I am using breadboard instead of a ready made PCB for programmer.So the
connections in the breadboard as shown




NOTE:
Here I am not using crystal because I am thinking that you bought a new atmega32
or you are having an atmega32 which is not using external crystal(not done fuse
bits). If your microcontroller had done fuse bits then you have to use a proper
crystal. I will explain about it in Fuse Bits section.


                                          18
Now go to Tools-> Program




                            19
COMMON ERRORS IN AVR PROGRAMMING

First Error

avrdude: AVR device not responding
avrdude: initialization failed, rc=-1
    Double check connections and try again, or use -F to override
    this check.


avrdude done. Thank you.

make.exe: *** [program] Error 1

Second Error:




                                        20
A small circuit, but too many errors???????.

TROUBLESHOOTING
  1. First check whether your parallel port is working or not using lpt.exe. You can
     get more explanation on my previous book- MY EXPERIENCE ON PARALLEL
     PORT INTERFACING.
  2. See bios settings. Better set for bidirectional mode, but spp and ecp modes will
     also work. See the address of the parallel port(0x378). See my bios settings in my
     previous book - MY EXPERIENCE ON PARALLEL PORT INTERFACING.


                                          21
   3. You connected reset pin to external Vcc or gnd ( disconnect it)
   4. External power supply may be off
   5. Parallel port cable may be not fitted properly.
   6. See whether u interchanged MISO and MOSI
   7. See whether ur parallel port is working or not by using LPT.exe
   8. See for short-ckt between pins
   9. See for any loose connection in wires using Continuity tester of multimeter
   10. Some parallel ports won't work like that of Intel915 because they have special
       protection, i don't know much about it. I have tried parallel port interfacing on it
       but data port was not properly working.
   11. If you are using soldered wires then see for any short circuit or loose
       connections in solderings
   12. Ground of power supply and parallel port should be short circuited.
   13. Execute install_giveio.bat for acessing ports

Now the main problems are


Yikes! :- I have faced it, but after sometime i again programmed it(i might have done
some hardware repairs), it worked properly. This is mainly due to lack of power
supply.

Verification Error:- This is due to loose contact with wires. If u keep wires just touched
with parallel port(once i tried with hand for connecting parallel port and wires to uC),
then this occured. This occur when u remove crystal when programing(after doing
fuse bits)
So u check the following things:-

1. Check breadboard, new breadboards have this problem(some parts don't have good
connection)
2.Check ur parallel port with lpt.exe
3. See any loose contact.
4. See the tips i said above
MOST IMPORTANT TIP
Always see the voltage at the Vcc pin of the microcontroller. It should not be greater
than 5V, if it is greater than 5V then your microcontroller will get burned. See the
Vcc of the microcontroller when you switch on the power supply. The other thing
you have to remember is about fuse bits.

                                           22
If you are not working with WinAVR2006 and you are using AVRStudio, then you can
use the same programmer. Only difference is that you have to work in text mode.
Install AVRDUDE then execute install_giveio.bat for acessing ports. Now change to
the avrdude\bin> directory and do the following shown




Here f.hex is the hex file we had to load into the chip. If you installed WinAVR2006
then change the director to C:\WinAVR\bin> and execute the above command. See
the AVRDUDE documentation for more about it.


Now check the program loaded into the memory. Remove the Reset pin and connect
Reset pin to VCC because the value at Reset pin is LOW by default and chip is reset
( i am talking about the parallel port voltage).

You can see that all ports except PORTC pins C2,C3,C4,C5 are not blinking. This is
because your chip's JTAG has been enabled. If you want to use PORTC pins further
then you have to disable JTAG. This is done by using fuse bit settings.


                                          23
                                    FUSE BITS

                                     You have to do fuse bits to disable JTAG,lock the
microcontroller, change the clock frequency of the microcontroller. So let's study
AVRDUDE in terminal mode. First enter in the terminal mode and see the fuses.See
page 255 of atmega32 datasheet, then you will get some ideas about fuse bits.




                                          24
Use 'part' command to display details about the microcontroller




                                         25
           SETTINGS FOR EXTERNAL CRYSTAL AND JTAG DISABLE

See below how I had done fuse settings for external crystal. You can see some error
occurred, this is due to the lack of crystal. The connection in the crysal side should be
proper with proper use of crystal and capacitors. Here I set the microcontroller for
3-8Mhz crystal. Compare what i had done with that of in datasheet.




                                            26
IMPORTANT NOTES ON FUSE BITS:
  1. Always keep a screenshot fuse bits settings you do for future reference.
  2. Do Fuse Bit's at your own risk. See the link below
     http://www.roboticsindia.com/modules.php?name=Forums&file=viewtopic&
     t=1412&p=7120
  3. Do remember the fuse settings.
  4. The crystal you use should be proper to produce the clock to the crystal.
  5. Use proper capacitors. I used 22pF,33pF even 150pF. But better to use the
     prescribed values in the datasheet.
  6. Mostly you will get problem after fuse bit settings, so be thorough with fuse bits
     before you are doing.
  7. If you are doing fuse bits for external crystal, remember that after doing fuse
     bits you can't even program chip without a proper crystal and capacitors.

                                DISABLING JTAG
After disabling JTAG you can use PORTC properly. Pins C2,C3,C4,C5 are properly
used for other applications. i.e, we got one port for other applications. When I brought
my new microcontroller for the first time I thought that the microcontroller was not
good because PORTC pins are not working, then I later came to know that it is due to
JTAG only.




                                          27
See what happened when I removed the RESET pin of the microcontroller . Here I
downloaded blinking program to see whether PORTC is working and I removed the
RESET pin connection with parallel port, that is why the fuse read as 0xff




                                      28
             DISABLING JTAG AND USING INTERNAL 8Mhz CLOCK
                                      You can see that serial port baud rate depends on
the clock. So if you use 1Mhz clock then the maximum speed possible with less errors
is 4800bps (.2% error). But for high baud rate cannot be used with 1Mhz internal clock,
so we have to use 8Mhz internal clock, then you can use all baud rates with less error.




In the first case after changing the fuse bits I removed the RESET pin to see whether I
got 8Mhz. It worked according to the previous program: blink.c, I got fast blinking.
Don't remove the programmer before you leave the terminal mode of
AVRDUDE.That is what happened in the first case.

                                           29
                         INTERFACING LCD WITH AVR

LCD used: JHD162A(see in my parallel port book for more about it)




This is the simple schematic without using backlight and contrast pins. Here control
pins are connected to PORTD and datapins to PORTA. See the figure below.




                                         30
31
32
Folder:lcd

/*----------------------------------------------------------------
-------------CONNECTION BETWEEN LCD AND ATMEGA32-----------------
-----------------------------------------------------------------*/
#define DATA_DDR                  DDRA
#define DATA_PORT PORTA


#define CONTROL_DDR               DDRD
#define CONTROL_PORT          PORTD
#define Enable_Pin            6
#define RegSelect_Pin 4
#define ReadWrite_Pin 5
#define CONTROL_MASK         0X70


Here are the declaration I am using. Here CONTROL_MASK is used so that remaining
pins can be used for other purpose. Change the port settings here so that you can use
same code for all ports. When you program you should program in such a way that
port pins are not wasted and same program can be used irrespective of ports. So do
this at the beginning of the program for better understanding of the program and
portability. Practice this when you do programming. Rest program remain same as
that I had given my previous book for parallel port.




                                         33
        SOME IMPORTANT COMMANDS USED FOR PROGRAMMING

You might have seen command _BV(a) the equivalent of it is 1<<a , for this you go to
WinaVR2006 directory
D:\WinAVR\avr\include\avr>
open the included files so that you can get more information for atmega32 it is iom32.h

Eg: _BV(6)= 01000000

Suppose if you want to set 5th pin of PORTD then write

PORTD|=_BV(5);

Here we are using logic OR to set a pin, remaining pins remain same because
according to logic operations A+1=A(OR gate) and A+0=A. Do some examples then
you will understand it better.

Suppose if you want to clear 4th bit in PORTD then write

PORTD&=~(_BV(4));

~(_BV(4) ) = ~(00010000) = 11101111

This value logic AND with PORTD and writing it to PORTD again will make that bit
clear. Remember A.1=A and A.0=0




                                          34
                         L293D INTERFACING WITH AVR


L293D used as H-bridge to drive DC motor. It can drive a bipolar stepper motor. I
have explained more about in my first book for robotics. Here are the pictures for
connecting L293D to AVR.




                                          35
This figure shows connecting a motor to L293D. Here I applied 12V from adapter to
the pin8 of L293D. I used a normal 12V,250mA DC motor.




                                        36
/*----------------------------------------------------------------
-------------CONNECTION BETWEEN L293D AND ATMEGA32---------------
-----------------------------------------------------------------*/
#define L293D_DDR                 DDRC
#define L293D_PORT PORTC
#define Pin_1            0
#define Pin_2                     1
#define L293D_Mask 0x03
/*----------------------------------------------------------------
-------------CONNECTION BETWEEN INPUT AND ATMEGA32---------------
-----------------------------------------------------------------*/
#define Input_DDR                 DDRD
#define Input_PIN                 PIND
#define IPin_1            6
#define IPin_2                    5
#define Input_Mask 0x60

Here I am using PORTC to connect to L293D and PORTD for input pins to test H-
bridge. L293D_Mask,Input_Mask is used so that remaining pins of the port can be
used for other purposes.

/*----------------------------------------------------------------
-----------------FUNCTIONS TO INITIALIZE PORTS--------------------
-----------------------------------------------------------------*/
void Init_Ports(void)
{
L293D_DDR|=(_BV(Pin_1 )|_BV(Pin_2)); //setting pins for output
L293D_PORT&=~(_BV(Pin_1 )|_BV(Pin_2));//starting motor is Off
Input_DDR&=~(_BV(5)|_BV(6));//making as input pins
}

Here the L293 DDR is used for ouput and L293D_PORT is set LOW to stop motor at
the starting.
a=((Input_PIN&_BV(IPin_1))>>(IPin_1));
b=((Input_PIN&_BV(IPin_2))>>(IPin_2));
These statements give a,b= 0 or 1. I used right shifting operation here. Now you can
drive a robot using L293D.
                                         37
BIPOLAR STEPPER MOTOR DRIVING USING AVR




                  38
for more about stepper see my previous books




                                       39
/*----------------------------------------------------------------
-------------CONNECTION BETWEEN L293D AND ATMEGA32---------------
-----------------------------------------------------------------*/
#define L293D_DDR                 DDRC
#define L293D_PORT PORTC
#define Pin_1            0
#define Pin_2                     1
#define Pin_3            2
#define Pin_4                     3
#define L293D_Mask 0x0f

Here are the connections used

int steps[]={15,13,12,14};

the steps sequence used for the bipolar stepper motors are shown in arrya. This will
make 4 steps. Repeat this sequence again for continous motion.

FOLDER:bipolarstepper




                                         40
                  UNIPOLAR STEPPER MOTOR INTERFACING


Here I used power transistors instead of ULN2003. The NPN power transistors are
used for driving. The base of transistor are connected to the microcontroller ports and
emitter grounded and the collector is connected to the points of the stepper motor. The
common ends of both coils are connected to the Vcc=12V (from adapter) of the power
supply.
FOLDER:unipolarstepper




                                          41
Have a closer look




/*----------------------------------------------------------------
-------------CONNECTION BETWEEN L293D AND ATMEGA32---------------
-----------------------------------------------------------------*/
#define L293D_DDR                 DDRC
#define L293D_PORT PORTC
#define Pin_1            0
#define Pin_2                     1
#define Pin_3            2
#define Pin_4                     3
#define L293D_Mask 0x0f
int steps[]={9,3,6,12};
Here only steps changed,rest remain same. Remember to put the program in infinite
loop for continuous rotation of motor.

                                        42
               KEY ENCODER INTERFACING




FOLDER:74922

                         43
/*----------------------------------------------------------------
-------------CONNECTION BETWEEN 74922 AND ATMEGA32---------------
-----------------------------------------------------------------*/
#define IC_DDR               DDRC
#define IC_PORT PORTC
#define IC_PIN                    PINC
#define Pin_A             0
#define Pin_B                     1
#define Pin_C             2
#define Pin_D                     3
#define Pin_DA              4
#define Pin_OE                    5
#define IC_Mask 0x10 //OE for output remaining for input
#define Output_DDR DDRD
#define Output_PORT PORTD

#define Output_Enable IC_PORT&=~_BV(Pin_OE) //for enabling the IC

Here I am using a single port for connecting the pins of 74922. You can see that all
pins are input except Ouput Enable. So you have to configure that pin for output and
it should be active low.

IC_DDR=IC_Mask; //setting OE pins for output,remaining for input

Here I take input from PORTC and outputting the key pressed to PORTD. See the
capacitor values otherwise keydebouncing will occurs, it should be C and 10C
respectively. See the datasheet for more reference.


Now let's see the keypressed on LCD. So I am using the previous program in the
folder 'lcd' to a normal .c file after removing the main() function. Put that .c file in
same directory and send the value to the LCD. Before sending we should make it
ASCII value for displaying on LCD. '0' in hexadecimal corresponds to 48 in ASCII. We
have to do same with alphabets also. See the code, you will understand better. See the
diagram below for the circuit.

                                          44
FOLDER:74922_LCD




                   45
               7-SEGMENT DISPLAY INTERFACING WITH AVR

                             Here I am giving how to connect 7 segment to AVR
without using any decoder(7447). I am using a common anode display. So to turn on
individual LED's you should apply LOGIC LOW to the other end of LED's.




                                        46
/*----------------------------------------------------------------
-------------CONNECTION BETWEEN 7 segment AND ATMEGA32-----------
-----------------------------------------------------------------*/
#define DATA_DDR                  DDRC
#define DATA_PORT PORTC
#define Pin_a                    0
#define Pin_b                    1
#define Pin_c                    2
#define Pin_d                    3
#define Pin_e                    4
#define Pin_f                    5
#define Pin_g                    6
#define Pin_Dec              7
#define DATA_MASK 0XFF

Here are the connections between 7segment and AVR. The pins are connected to the
PORTC and the individual pins connections are shown above.

FOLDER:one7seg


do
 {
 Display(i);
 i++;
 if(i>9) i=0;
 delay_ms(500);
 }
 while(1);

These statements run the 7-segment from 0 to 9 with a delay of 500ms. Display is
used to display the value on 7-segment. Here I used two 7-segment, i showed in
diagram, but both are common and no need for one 7-segment.


                                         47
                      MULTIPLEXED 7-SEGMENT DISPLAYS

Here we use the technique of persistance of vision. i.e, our eye cannot detect what is
happening in 1/16 of a second. So any happening within that time will be seen
continous by our eye. This technique is used in television, even used to program
CRO's for some games.




I am using 74126, tristate buffer to give power supply to the 7segment. You can use
transistors in case of common cathode display. But here I am using common anoder
displays.

FOLDER:2-7seg


                                           48
                                     IC TESTER




Try to make one IC TESTER. In the previous book I made one which requires atleast 5-
 6 IC's. Suppose if you use a 40 pin AVR then you can make it with a single AVR. The
 advantage is that the individual pins can be set for input as well as output. There are
 3 i/o ports which is connected directly to the IC to be tested. For each IC pin diagram
   will be different. That is we have to configure those 24 pins as input port or output
    port as per the IC number. This can be divided into three categories, DDR (data
   direction register in atmega32), data out and data in. We are using only one port to
 communicate with computer. Therefore we have got at max 8 pins. In that one nibble
is used for data transfer only and the other nibble for determining the following things



                                          49
· Of which port is the data in the most significant nibble of porta. That is portb
   lowest nibble, portb highest nibble, portc lowest nibble, portc highest nibble,
   portd lowest nibble or portd highest nibble.
  What kind of data is in the least significant nibble. That is value to be stored in
  DDR (data direction register of atmega32), PORTA/B/C (value to be outputted
  to data register of PORTB/C/D) or PINB/C/D (value to be inputted from pins
  of PORTB/C/D).


   Now its clear that there are three combinations for what kind of data is available
   in most significant nibble. Also 6 nibbles are to be controlled. So total we need
   18 different kind of data to be transferred through most significant nibble.
   Remaining number of bits to control this is only four. With four using usual
   convention only 16 combinations can be made. For this, the strategy we
   implemented is as follows,
   D0-D3 of PORTA is first four the least significant bits, ie least significant nibble.
   Now, initially we will set this to 0000. The first bit which becomes high will
   decide what kind of data is in the bits D4-D7 of PORTA. Suppose first D3
   becomes high, then the data in the bits D4-d7 of PORTA is DDR. Suppose first
   D2 becomes high, then the data in the bits D4-d7 of PORTA is PORTB/C/D.
   Suppose first D1 becomes high, then the data in the bits D4-d7 of PORTA is
   PINB/C/D. After this what we want to know is, of which nibble should the
   data in the bits D4-D7. This is determined by the remaining bits, ie suppose first
   D1 becomes high, then the remaining bitw D3,D2,D0 will determine that. If
   D3,D2,D0 is 010, it means data in the bits D4-D7 belongs to most significant
   nibble of PORTB, ie D4-D7 of PORTB. And since first D1 becomes high it
   implies PINB/C/D. So the value in D4-D7 of PORTA is the value from D4-D7 of
   PORTB. In this way we can get and write values to all 24 pins.




                                            50
                                     UART of AVR




                                            It is basically used for asynchronous
communication, a communication with 3 wires(Rx,Tx and ground). So first see the
uart of AVR. See the datasheet for the registers in the UART. So let's go for the first
program which tests your serial port.

Folder: serial1

This program is meant for 1MHz internal oscillator working AVR's. Just short circuit
RX and TX (D0,D1) of AVR and see the value at PORTC. If the value at PORTC is 0x99
then your serial port is working fine.

Troubleshooting
   1. See at 1MHz 2400 bps the error is .2%, but if you go for 9600 bps then error is
      around 8.3%(refer datasheet baud rates).
   2. You should disable the JTAG for acessing PORTC, see fuse bits.
   3. Short circuit Rx and Tx.

Now you can confirm that your microcontroller uart is working fine.




                                            51
SERIAL PORT OF COMPUTER




          52
                                  BIOS SETTINGS




First set the bios then only do any other operations like programming the
microcontroller and serial port. See the Port numbers correctly. Then only use the
COM1, COM2 or lpt1,lpt2 repectively. This is the most important step. AVRDUDE
programmer sometimes won't work for some parallel port. It does not worked for
INTEL965GV motherboard. So see my previous book on parallel port before doing
these steps.




                                         53
                 SERIAL PORT INTERFACING WITH COMPUTER


                                       For interfacing AVR with serial port of cable you
require a serial port cable and max232 or HIN232(level converter). RS-232 of the
computer has LOGIC HIGH in the range of -3 to -25V( mostly around -8.5V) and
LOGIC LOW around 3 to 25V (mostly 8.5V). We had to convert it to LOGIC
HIGH(5V) and LOGIC LOW(0V) of microcontroller, so we use max232 or you can use
any other level converters. Next is to get a serial port cable,if you are not getting a
serial port cable, then buy a serial mouse costs around Rs.70 and take the cable from it.
But mouse serial port cable has only 4 pins Rx,Tx,DTS,GND, so it can't be used for
programmer's of some microcontrollers. But in our case we require only 3
pins(Rx,Tx,GND). So it is better to go for a serial cable, I used one that of mouse.




                                           54
Figure shows the connections with serial port of computer. You can use a 1uF
capacitor instead of 10uF.




                                         55
56
57
                                HYPER TERMINAL


                               Hyper Terminal is used to see the serial port data. It
will show only the received data. All the data is show in ASCII. Go to
Start_Programs_Accessories_Communicatin_Hyper Terminal. If you are using serial
port for your internet you have to disconnect it for acessing serial port. Run Hyper
Terminal then some screen come for asking area codes, put some garbage value and
press OK and in the next page press OK, then you will come to this page.




                                          58
If you use some USB to RS232 converter, then I can't say that Hyper Terminal will
work.




                                         59
See in the device manager for the port settings.
Device Manage COM Properties




                                           60
Testing your computer Serial Port:
Short circuit Rx and Tx of your computer and type letters keeping hyperterminal
working. If you can see what you are typing(i.e, if you type 'a' then it is displayed as 'a'
on the hyperterminal) then you can infer that your serial port will work properly.
Don't use ground and other pins,leave all other pins open and just short circuit pin2
and pin3(Rx and Tx).




Now connect serial port to max232, then short circuit the Rx and Tx of max232 ie pin
11 and pin 12 and type something in hyperterminal, see what you are getting. If you
are getting the alphabets you typed then your connections are proper. Max232 is
working fine. By default the TTL output is 5V. See the RS232 output corresponding to
5V input, it should be mostly in the range -8V to -10V. See these conditions properly
otherwise your microcontroller will get burned because voltage greater than 5V is
damagerous to the microcontroller.

                                            61
FOLDER:serial_computer

Here this code will send back next ASCII you type. See the error in baud rates for
different clock frequencies. Here I am using 2400 8 N 1 with 1Mhz internal crystal. If
you want more speed then go for internal 8Mhz crystal. But still error is around .2%,
so if you want 0% error in baud rate go for crystal 3.6864Mhz or crystals given in the
datasheet which is having 0% error in baud rate
TransmitByte(ReceiveByte()+1);

You can use terminal program inbuilt in WinXP or Bray's terminal for serial port
interfacing with computer. Bray's terminal is a free software with more options than
hyperterminal. Hyperterminal won't show the transmitted data, it shows only the
received data.

SERIAL PORT TROUBLESHOOTING AND ERRORS:




When synchronisation is lost you will get xxxxxxxxxxxxxxxxx displayed on
hyperterminal. So be thorough about the micrcontroller clock and baud rate you set.
This is the most important error occurs with serial port. If you use a C program then
you will get some different values other than the values you sent. Remember only one
program can acess serial port at a time. Sometimes Turbo C is having problem in
acessing serial ports. I am attaching a C program with it.

                                          62
See the connections




                      63
64
                         SERIAL PORT with LCD DISPLAY


FOLDER: serialport_lcd




                                      65
66
67
//lcd initializations
      Init_Ports();
      Init_Lcd();
  InitUART( 25 ); /* Set the baudrate to 2400 bps using a 1MHz crystal */
  for(;;)        /* Forever */
  {
  a=ReceiveByte();
  Lcd_Send(a);
      TransmitByte(a); /* Echo the received character */
  }




First initialising LCD ports and start initialising baud rates. First we receive the data
from serial port and send it to LCD first then it is again send back to serial port. But
this process will be having some delays because of the delays inserted in the LCD
functions.


                                            68
INTERNAL ADC OF AVR

                                   See the datasheet for the registers. Atmeg32 has 10 bit
ADC having two registers ADCL and ADCH. But we are using it in 8 bit resolution, so
that error will be lowered. But there will always be noise error in the reading. I used
LM35, got error about .01V. See even conversion is of 10 bit resolution and we are
using 8 bits resolution(i.e, first 8 bits leaving last two LSB's). In 8 bit resolution mode
we read ADCH. If you want to read 10 bits then use ADC(see in the include file, you
will understand better). I used internal analog voltage reference of 2.56 volt.
Remember to use a capacitor in the AREF pin, use a .01uF capacitor. The choice of
capacitance will affect the reading. See in the datasheet how to avoid noise better. I
tried with .1uF and .01uF capacitors. Here I am using LM35 temperature sensor to
ADC input.




                                            69
FOLDER:lm_2-7seg

See the problem with persistance of vision. Here the temperature varies with time and
it is shown on LED i.e, it is shown a non decimal value.
ADCSRA|=_BV(ADSC); //start conversion
while(!((ADCSRA&_BV(ADIF))>>ADIF));
return ADCH;

Here I am using single conversion mode. I am waiting for the conversion to end and
we are using 8 bit conversion mode. The 8 bit converted value is there in ADCH
register and we are returning the values.


                                         70
                         ADC with SERIAL PORT and LCD


void Init_ADC(void)
{


     ADMUX|=(_BV(ADLAR) | _BV(REFS1)| _BV(REFS0)) ;
     // RFS1 and RFS0 are for Internal Reference voltage of 2.56V AND 8 BIT
CONVERSION
     ADMUX&=~(_BV(MUX0)|_BV(MUX1)|_BV(MUX2)|_BV(MUX3)|
_BV(MUX4)); //SELECTING CHANNEL0
  ADCSRA|=(_BV(ADEN) | _BV(ADPS2) | _BV(ADPS0)) ; //normal conversion
without interrupt
     ADCSRA&=~(_BV(ADSC)|_BV(ADATE)|_BV(ADIF)|_BV(ADIE)|
_BV(ADPS1));//clock/32 speed

}

int Read_ADC(void)
{
ADCSRA|=_BV(ADSC); //start conversion
while(!((ADCSRA&_BV(ADIF))>>ADIF));
return ADCH;
}


See the ADC declarations and initializations.




                                          71
if(a!=b)
{
//first delete the previous values for uart
       for(i=0;i<2;i++)
       {
       TransmitByte(del[i]);
       }

//for LCD we require initialiatization
      Init_Lcd();
      for(i=0;i<12;i++)
      Lcd_Send(str[i]);




j=a%10;

k=a/10;
k=k%10;
Lcd_Send((k+0x30));
TransmitByte((k+0x30));

Lcd_Send((j+0x30)); //since both will display ASCII values, we convert decimal to
ASCII
TransmitByte((j+0x30));

b=a; //for next value
//delay sometime (1s) otherwise LCD display will run
      delay(1000);

we are seeing for any change in the temperature reading, if any change occurred then
it is send it to the LCD and serial port. We are using 'BACKSPACE' to delete the
previous values in case of serial port. Here I am clearing LCD and writing to it , but
you can do other way by selecting the instruction register and moving to location 0x8c
and 0x8d to write the temperature on that locations.


                                              72
TROUBLESHOOTING:

  1. Always remember about the fuse settings and frequency of the crysal you are
     using. Set the baud rate according to it.
  2. See the baud rate errors. Better to use a maximum error of .2%,better don't go
     for baud rates of errors 8.3%.
  3. Refer datasheet for the baud rate before setting it.
  4. Put noise cancellation capacitance in the AREF pin.
  5. See the Hyper Terminal settings, about the port is it COM1 or any other port,
     see the bios settings.




                                         73
                                       TIMERS


void main()
{
InitUART(25);
TCCR0|=(_BV(CS02)|_BV(CS01));
do
{
TransmitByte(TCNT0);
delay_ms(500);
}
while(1);
}

Here I am using external clock for running the timer. The clock is set falling edge. But
if you keep T0 pin open then the counter will run counting. Better connect T0 pin to
Vcc or ground. Include “serial.c” for serial port transmission.

Which one should I choose Atmega32 or Atmega32L??

I prefer Atmega32l because its low power consumption and cost. Cost difference is
around Rs.50 or more and second thing it works on low power which is very
adavantegous in robotics because the power supply won't be consumed much.
Suppose if you make a robot using some transistors and OPAMP's then the power
consumption of that circuit will be more and motor will draw more current which will
sometimes cause the control circuit to improper working. But atmega32l works from
2.7V – 5V and with even low voltage. You might have noticed that it works with the
voltage from the parallel port without connect any Vcc to the chip. After
programming the chip, switch off the adapter then also avr works with the voltage
from parallel port. This shows how less is the power required to run the chip. This is
the main advantage of using microcontroller instead of normal transistors and
OPAMPS for robotics. I don't think clock frequency does not matter much for us since
atmega32l maximum frequency is 8MHz. The sensitivity of a sensor is in the range of
milliseconds or 100 uSec not more than that and we are mainly processing the sensor
signals,still we are getting 8000 cycles for processing. This much time is more than
enough for us.
                                           74
IMPORTANT THINGS TO REMEMBER FOR MICROCONTROLLER TROUBLESHOOTING


1. Always see that the voltage (Vcc) to the microcontroller should not be greater
    than 5V.
2. See your parallel port and serial port settings on BIOS before starting with
    microcontrollers.
3. Always keep a screenshot of the fuse bit settings you are doing.
4. Main reasons which cause AVR to burn:
      microcontroller voltage>5V
     fuse bits had done wrongly(lock bits especially)
5. Before doing fuse bits, be thorough with what you are doing. Enable the proper
    modules only. Suppose if you use external clock then before doing fuse bits you
    should have a proper crystal.
6. Always see the register settings. Don't waste a full port for the use of a single
    input or output. Do proper commands,mainly _BV();
7. Apply proper noise cancellation. Use proper capacitance values.
8. See for the baud rate error corrections. Better use maximum possible error to
    .2%.
9. See the breadboard problems. This is a serious problem.
10. See my previous books for more troubleshooting.




                                       75
IR led identification
http://roboticsindia.net/modules.php?name=Forums&file=viewtopic&t=1438

sonar
http://www.robot-electronics.co.uk/htm/srf04tech.htm
http://www.robot-electronics.co.uk/htm/srf08tech.shtml
http://hamjudo.com/sonar/
http://www.rdrop.com/~cary/html/ultrasonic.html
http://www.leang.com/robotics/info/articles/minison/minison.html
http://www.robot-electronics.co.uk/htm/srf04tech.htm
http://www.interq.or.jp/japan/se-inoue/e_pic6_6.htm



ir vs sonar
http://www.roboticsindia.net/modules.php?name=Forums&file=viewtopic&t=1189

sms
http://www.riccibitti.com/tinyplanet/tiny_article.htm

sharp sensor
http://www.blueink.com/CLASS/physcom1/SharpGP2D12.htm
http://neil.fraser.name/software/lpt/

cro
http://www.roboticsindia.com/modules.php?name=News&file=article&sid=112

lcd
http://www.roboticsindia.com/modules.php?name=News&file=print&sid=75
http://www.beyondlogic.org/parlcd/parlcd.htm
http://www.eio.com/lcdintro.htm
http://home.iae.nl/users/pouweha/lcd/lcd0.shtml#hd44780
http://ee.cleversoul.com/lcd_project.html




                                        76
speech
http://www.vbip.com/miscellaneous/Speech-Recognition.asp
http://roboticsindia.com/modules.php?name=News&file=article&sid=115&mode=&
order=0&thold=0

7segment
http://www.iguanalabs.com/7segment.htm

general
http://homepage.hispeed.ch/peterfleury/

avrfreaks user projects
http://www.avrfreaks.net/index.php?module=FreaksAcademy&func=viewProjects&
startnum=76
software
http://www.avrfreaks.net/index.php?module=FreaksAcademy&func=viewProjects&
startnum=76

tachometer
http://www.xdesignlabs.com/digitaltach/


remote control
http://home.earthlink.net/~henryarnold/page33.html
http://scv.bu.edu/GC/shammi/ir/
http://www.ustr.net/infrared/sony.shtml
http://www.ustr.net/infrared/infrared1.shtml
http://www.ustr.net/



good link
http://www.sbselektronik.com/devreler.asp
http://www.geocities.com/stampic/links.htm




                                      77
fuse bits
http://www.roboticsindia.com/modules.php?name=Forums&file=viewtopic&t=1412
&p=7120

http://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&p=207381#
207381
http://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&t=36235




programmers

http://www.tuxgraphics.org/electronics/200510/article05101.shtml
http://www.users.on.net/~symes/Mega32/CandMega32.htm


good tutorials
http://www.users.on.net/~symes/CwithAVR/IntrotoCwithAVR.htm]
www.avrbeginners.net

mmc card interface
http://www.avrrepository.com/samplecode/sd_breakout/doc/index.html

avrdude problem
http://www.roboticsindia.net/modules.php?name=Forums&file=viewtopic&t=1318
http://www.roboticsindia.net/modules.php?name=Forums&file=viewtopic&t=1327
http://www.roboticsindia.net/modules.php?name=Forums&file=viewtopic&t=1332
http://www.roboticsindia.net/modules.php?name=Forums&file=viewtopic&t=1332
http://www.roboticsindia.net/modules.php?name=Forums&file=viewtopic&t=1241




                                      78
ir
http://roboticsindia.com/modules.php?name=News&file=article&sid=35&mode=&o
rder=0&thold=0
http://www.techgeek.com/subpage/index.phtml?topic=998&subtopic=996&item=10
17
http://www.acroname.com/robotics/info/articles/irlinear/irlinear.html
http://www.roboticsindia.net/modules.php?name=Forums&file=viewtopic&t=1427
&p=7184




                                    79

				
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