DEPARTMENT OF ELECTRONICS ENGINEERING

GOVERNMENT POLYTECHNIC COLLEGE, KOTTAYAM

SEMESTER V
5047 - EMBEDDED SYSTEMS LAB

PRACTICAL RECORD

Name:………………………………………………………

Roll No:…………………………………………………….

Register No:……………………………………………..

Batch:…………..….…… Class:……………………….
 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Notes:

1. In all simulations internal RC 1 MHz clock of ATmega32 is used in Proteus. So no external

crystal connected across XTAL1 and XTAL2 pins of ATmega32 in the circuit diagrams.
2. Atmel AVR Studio 5 (Ver 5.1.208) used to write code and generate HEX file.
3. Proteus 8.13 used to simulate ATmega32 circuits.

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SYLLABUS

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Arjun P, Lr. in Electronics Engg

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Arjun P, Lr. in Electronics Engg

Exp No. 0 Date: / /

FAMILIARIZATION OF AVR STUDIO & PROTEUS

Aim: To get familiarized with AVR Studio and Proteus software and create a new project

Requirements:

PC running Windows XP or later version with AVR Studio and Proteus Installed.

Theory:

AVR Studio is an integrated development environment (IDE) for developing and

debugging AVR microcontroller applications. AVR Studio provides a complete set of
features including project file management, a C/C++ editor, navigation and code
completion; a debugger supporting run control including source and instruction-level
stepping; registers, memory and I/O views; and target configuration and
management. AVR Studio supports all 8 and 32-bit AVR microcontrollers, and
connects seamlessly to debuggers and development kits

The Proteus Design Suite is a proprietary software tool suite used primarily for
electronic design automation. It is a Windows application for schematic capture,
Simulation, and Printed Circuit Board(PCB) layout design. It can be found in many
configurations, depending on the size of designs being produced and the
requirements for microcontroller simulation. Proteus is used mainly by electronic
design engineers and technicians to create schematics and electronic prints for
manufacturing printed circuit boards(PCBs) and also as a rapid prototyping tool for
R&D

Steps to Create a project in AVR Studio:

1. Open AVR Studio and select File->New->Project

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2. In new projects page ensure that C/C++ is selected in Installed Templates and AVRGCC C
Executable Project is selected. Give a suitable project name (here name given as Exp0).
Click OK.

3. In search window type atmega32. Now select Atmega32 from the list shown and click
OK.

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4. Now you get the programming window as shown

5. Type in the following code and press save button as shown

6. Now select Build->Build Exp0 to build the project and generate Hex File. If build is
successful without any error, we get a Build successful message in Output window.

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7. Hex file with same name as project will be generated inside Debug folder in the location
where we saved the project during Step 2. This Hex file will be used for Proteus
simulation.

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Arjun P, Lr. in Electronics Engg

Steps to Create a project and simulate it in Proteus:

1. Open Proteus Design suite and select File->New Project

2. Give project name and set path where the project will be saved. Click Next

3. Select DEFAULT Schematic Template. Click Next

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4. Choose Do not create a PCB layout. Click Next

5. Select No Firmware Project. Click Next

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6. Click Finish

7. Now we get the Schematic capture screen.

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8. Include parts by clicking on ‘P’ beside the toolbar. Now Pick Devices window will pop up.
In keyword search window type atmega32 and select ATMEGA32 from the list and click
OK.

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Arjun P, Lr. in Electronics Engg

9. Now ATMEGA32 will be added in our project as shown.

10. Similarly add an LED and resistor

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11. Now our project has 3 components ATMEGA32, LED RED and RES as shown. Click on
ATMEGA32 and click anywhere on the right grid. Now ATMEGA32 will be placed at that
location as shown

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12. Similarly place LED and resistor as shown.

13. Now wire the circuit. For this place mouse pointer at any terminal of a device. When the
cursor turns to a pencil symbol and a red dot appears, click left mouse button and drag
to the corresponding terminal to be connected in another device.

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14. Circuits need to be properly grounded. To add Ground click on Terminals mode, select
GROUND and click on the right grid.

15. Wire the corresponding components to ground

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16. Now we need to program ATMEGA32. For this Right click on ATMEGA32 and select Edit
Properties.

17. In Edit Component window that pops up, click on the folder symbol next to Program
File selection option. Browse to the location where the Hex file was created in Step 7 of
AVR studio project creation (Hex file will be inside Debug folder). Select the Hex file and
click Open. Then click OK in Edit Component window.

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18. The resistor value is now 10 Kilo Ohms. We need to change the resistor value to 330
Ohms. For this right click on the resistor R1 and select Edit properties.

19. In the Edit Component window that pops up, type 330 in the box corresponding to
Resistance and click OK.

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20. The completed circuit is shown below. Now click on the Run simulation button at the
bottom.

21. The circuit gets simulated and LED glows.

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22. You can Stop the simulation by clicking on Stop Simulation button as shown

Appendix 0:

VCC and GND pins of ATmega32 are hidden in an EDA software like Proteus. Proteus
inherently connects them to the internal VCC net and GND net. To see the default
voltage values in VCC net and GND net go to Design -> Configure power rails as shown

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Now power rail configuration menu pops up. Under Power rails section click on the drop
down menu next to Name and select VCC/VDD to see VCC net voltage. The default
VCC/VDD Net voltage will be shown (here it’s 5V as shown) below. If required we can
change this voltage to a different value. Similarly select GND to see GND net voltage.
GND net voltage is set to 0V and is not editable.

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Exp No. 1 Date: / /

LED Blinking
Aim:

To blink two LEDs alternately with 1s time period.

Requirements:

PC running Windows XP or later version with AVR Studio and Proteus Installed.

Components/Terminals in Proteus: ATMEGA32, LED-RED

Theory:

Blink an LED connected to any port B pin of ATMEGA32. PORTB is configured as an output port.
The LED is made to switch on and off in regular intervals of 1s. So PORTB is made high and low
continuously in regular intervals of 1s.

Circuit Diagram:

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Algorithm:

1. Set PORTB as output by initializing DDRB register with 0xFF

2. Make PORTB high by writing 0xFF to PORTB
3. Call 1000 ms delay
4. Make PORTB low by writing 0x00 to PORTB
5. Call 1000 ms delay

Code:
#define F_CPU 1000000UL //1 MHz clock
#include <avr/io.h>
#include <util/delay.h>

int main(void)
{
DDRB = 0xFF; //port B configured as output port
while(1)
{
PORTB = 0x01; //PORTB Pin0 made high, Pin1 made low
_delay_ms(1000); //call delay
PORTB = 0x02; //PORTB pin0 made low, pin1 made high
_delay_ms(1000); //call delay
}
return 0;
}

Result:

Connected an LED to AVR microcontroller and observed Blinking of LED.

For Office use only Signature of Lab in charge Remarks

Completion of Experiment

Dept. of Electronics Engg, GPTC Kottayam Page 25

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Arjun P, Lr. in Electronics Engg

Exp No. 2 Date: / /

Read the status of a switch and display it on an LED

Aim:

To read the status (ON/OFF) of a switch and display the status by turning ON/OFF an LED

Requirements:

PC running Windows XP or later version with AVR Studio and Proteus Installed.

Components/Terminals in Proteus: ATMEGA32, RES, SWITCH, LED-GREEN, DC, GND

Theory:

PORTC is configured as an input port and PORTB is configured as an output port. Switch is
connected to PORTC Pin 2 and LED connected to PORTB Pin 0.

Circuit Diagram:

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 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Algorithm:

1. Set PORTB as output by initializing DDRB register with 0xFF

2. Set PORTC as input by initializing DDRC register with 0x00
3. Read status of switch by reading value of PORTC Pin2. If it is high (Switch is open), Turn
OFF LED by outputting 0x00 on PORTB. If it is low(Switch is closed), Turn ON LED by
outputting 0xFF on PORTB

Code:
#include <avr/io.h>

int main(void)
{
DDRB = 0xFF; //port b is output
DDRC = 0x00; //port c is input
PORTB = 0x00;
while(1)
{
if (PINC & (1<<2))
{
PORTB = 0x00;
}
else
{
PORTB = 0xFF;
}
}
return 0;
}

Result:

Status of switch has been read and displayed on LED.

For Office use only Signature of Lab in charge Remarks

Completion of Experiment

Dept. of Electronics Engg, GPTC Kottayam Page 27

 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Exp No. 3 Date: / /

Drive a lamp load using relay

Aim:

To turn ON a lamp connected to a relay when a Switch is pressed.

Requirements:

PC running Windows XP or later version with AVR Studio and Proteus Installed.

Theory:

PORTC is configured as an input port and PORTB is configured as an output port. Switch is
connected to PORTC Pin 2 and Relay connected to PORTB Pin 0. Lamp and series battery are
connected to ‘Normally Open’ terminal of relay.

Components/Terminals in Proteus: ATMEGA32, RELAY, RES, CELL, SWITCH, LAMP, DC, GND

Circuit Diagram:

Dept. of Electronics Engg, GPTC Kottayam Page 28

 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Algorithm:

1. Set PORTB as output by initializing DDRB register with 0xFF

2. Set PORTC as input by initializing DDRC register with 0x00
3. Read status of switch by reading value of PORTC Pin2. If it is high (Switch is open), relay
will be kept off by outputting 0x00 on PORTB. If it is low, relay will be turned ON by
outputting 0xFF on PORTB. Now Lamp circuit will be completed and Lamp glows.

Code:

#include <avr/io.h>

int main(void)
{
DDRB = 0xFF; //port b is output
DDRC = 0x00; //port c is input
PORTB = 0x00;
while(1)
{
if (PINC & (1<<2))
{
PORTB = 0x00;
}
else
{
PORTB = 0xFF;
}
}
return 0;
}

Result:

Observed the switching of relay and lamp turning ON.

For Office use only Signature of Lab in charge Remarks

Completion of Experiment

Dept. of Electronics Engg, GPTC Kottayam Page 29

 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Exp No. 4 Date: / /

Optoisolator Interfacing

Aim:

To interface an Optoisolator with AVR microcontroller

Requirements:

PC running Windows XP or later version with AVR Studio and Proteus Installed.

Theory:

PORTC is configured as an input port and PORTB is configured as an output port. Switch is
connected to PORTC Pin 2 and Relay connected to PORTB Pin 0. Lamp and series battery are
connected to Optoisolator output

Components/Terminals in Proteus: ATMEGA32, 4N35, RES, CELL, SWITCH, LAMP, DC, GND

Circuit Diagram:

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 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Algorithm:

1. Set PORTB as output by initializing DDRB register with 0xFF

2. Set PORTC as input by initializing DDRC register with 0x00
3. Read status of switch by reading value of PORTC Pin2. If it is high (Switch is open),
optoisolator will be kept off by outputting 0x00 on PORTB. If it is low, optoisolator will
be turned ON by outputting 0xFF on PORTB. Now Lamp circuit will be completed and
Lamp glows.

Code:

#include <avr/io.h>

int main(void)
{
DDRB = 0xFF; //port b is output
DDRC = 0x00; //port c is input
PORTB = 0x00;
while(1)
{
if (PINC & (1<<2))
{
PORTB = 0x00;
}
else
{
PORTB = 0xFF;
}
}
return 0;
}

Result:

Optoisolator interfaced with AVR and a lamp has been turned ON using it.

For Office use only Signature of Lab in charge Remarks

Completion of Experiment

Dept. of Electronics Engg, GPTC Kottayam Page 31

 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Exp No. 5 Date: / /

Temperature sensor interfacing with AVR using ADC peripheral of ATmega32

Aim:

To interface Temperature sensor with AVR microcontroller using ATmega32 ADC

Requirements:

PC running Windows XP or later version with AVR Studio and Proteus Installed.

Theory:

To use ATmega32 ADC, the analog input need to be connected to PORTA pins which are
multiplexed as ADC input pins (labeled as ADC0 to ADC7). LM34 Temperature sensor (Pin 2) is
connected to PORTA Pin 0(ADC0 pin) of ATmega32. PORTA is configured as an input port and
PORTD is configured as an output port. 8 LEDs connected to PORTD will display the LM34
Temperature reading in 8 bit binary.
LM34 series are precision integrated-circuit temperature sensors whose output voltage is
linearly proportional to the Fahrenheit temperature. It outputs 10 mV for each degree of
Fahrenheit temperature.
The ADC has 10-bit resolution. So number of steps will be 1024. We use the internal 2.56 V
reference voltage as Vref, so the step size would be 2.56 V/1024 = 2.5 mV. LM34 sensor
produces 10 mV for each degree of temperature change and the ADC step size is 2.5 mV. So
each degree of temperature change corresponds to 4 ADC steps(10 mV/2.5 mV = 4).This makes
the binary output number for the ADC four times the real temperature. So the 10-bit output of
the ADC is divided by 4 to get the real temperature. To divide the 10-bit output of the ADC by 4
we choose the left-justified option and only read the ADCH register. It is same as shifting the
result 2 bits right (division by 4 in binary).
A 100nF capacitor is connected between the AREF pin and GND to make Vref voltage more
stable and increase the precision of ADC. LM34 Pin 1 and ATmega32 AVCC pins are connected
to 5V DC.

Components/Terminals in Proteus: ATMEGA32, LM34, CAP, LED-RED, DC, GND

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Circuit Diagram:

Algorithm:

1. Set PORTD as output by initializing DDRD register with 0xFF and PORTA as input by
initializing DDRA register with 0x00.
2. Write 0x87 to ADCSRA register. This will enable ADC and set ADC Prescaler Select bits to
111 (to select Fosc/128 for ADC clock, where Fosc is the crystal frequency connected to
the AVR)
3. Write 0xE0 to ADMUX register. This will the set Reference selection bits to 11 (to select
Internal 2.56 V for Vref) and set ADLAR bit to 1 so that the10 bit conversion result will be
left adjusted and set Analog Channel and Gain Selection Bits to 00000 to select single
ended channel ADC0.
4. In a continuous while loop first set ADSC bit to 1 to start conversion.
5. Check whether ADIF flag of ADCSRA register is set. This bit is set when an ADC
conversion completes and the data registers are updated.
6. After the ADIF bit has gone HIGH, read the ADCH registers to PORTD to get the digital
data output in PORTD which lights up the corresponding LEDs to indicate binary value.

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Code:

#include <avr/io.h>

int main(void)

DDRD = 0xFF; //port D output

DDRA = 0; //port A input. LM 34 connected to ADC0
ADCSRA = 0x87; //ADc enable, ck/128
ADMUX = 0xE0; //2.56 V ref, ADC0 single ended left justified data

while(1)

ADCSRA |= (1<<ADSC); //start conversion

while((ADCSRA & (1<<ADIF))==0); //wait for EOC flag ADIF
PORTD = ADCH; //high byte to port B

return 0;

Result:

Interfaced LM34 temperature sensor IC using ADC peripheral of ATmega32 and observed the
binary output corresponding to the analog temperature value through LEDs.

For Office use only Signature of Lab in charge Remarks

Completion of Experiment

Dept. of Electronics Engg, GPTC Kottayam Page 34

 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Exp No. 6 Date: / /

DC Motor interface with AVR

Aim:
To monitor the status of a switch and perform the following:

(a) If Switch is open, the DC motor rotates clockwise.

(b) If Switch is closed, the DC motor rotates counterclockwise.

Requirements:

PC running Windows XP or later version with AVR Studio and Proteus Installed.

Theory:

PORTA is configured as an input port and PORTC is configured as an output port. Switch is
connected to PORTA Pin 0. DC Motor is interfaced to AVR through L298 Motor driver IC. Input
pins IN1 and IN2 of L298 are connected to PORTC pins 1 & 2 respectively. Enable pin ENA of
L298 connected to PORTC pin 0. DC Motor is connected across the output pins Out1 and Out2
of L298. L298 IC is provided with separate 5V DC supply.

Components/Terminals in Proteus: ATMEGA32, L298, MOTOR, RES, SWITCH, DC, GND

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 Embedded Systems Lab - 5047 Prepared by:
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Circuit Diagram:

Algorithm:

1. Set PORTC as output by initializing DDRC register with 0xFF and PORTA as input by
initializing DDRA register with 0x00
2. Initially disable L298 and set L298 IN1 = 0, L298 IN2 = 0 by writing 0xF8 to PORTC.
3. In a continuous loop, first enable L298 by writing 1 to PORTC pin 0.
4. Read status of switch by reading value of PORTA Pin 0. If it is low(Switch is closed), set
L298 IN1 = 0 and L298 IN2 = 1 by writing 0 to PORTC pin 1 and 1 to PORTC pin 2.
5. If it is high (Switch is open), set L298 IN1 = 1 and L298 IN2 = 0 by writing 1 to PORTC pin
1 and 0 to PORTC pin 2.

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 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Code:

#include <avr/io.h>

int main(void)

DDRA = 0;
DDRC = 0xFF;
PORTC &= 0xF8; //initially disable L298, L298 IN1 = 0, L298 IN2 = 0

while(1)

PORTC |= (1<<0); //enable L298

if ((PINA & 0x01) == 0)

PORTC &= (~(1<<1)); //L298 IN1 = 0

PORTC |= (1<<2); //L298 IN2 = 1

else

PORTC |= (1<<1); //L298 IN1 = 1

PORTC &= (~(1<<2)); //L298 IN2 = 0

return 0;

Result:

Interfaced DC motor with AVR microcontroller using L298 motor driver and using a switch
controlled the direction of rotation.

For Office use only Signature of Lab in charge Remarks

Completion of Experiment

Dept. of Electronics Engg, GPTC Kottayam Page 37

 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Exp No. 7 Date: / /

Servo Motor interfacing with AVR

Aim: To interface a Servo motor with AVR microcontroller.

Requirements:

PC running Windows XP or later version with AVR Studio and Proteus Installed.

Theory:

PORTC pin 0 is configured as an output port. Servo Motor control input pin is connected to
PORTC pin 0.
Servo Motor is a DC Motor equipped with error sensing negative feedback to control the exact
angular position of the shaft. Unlike DC Motors it will not rotate continuously. It is used to make
angular rotations such as 0-90°, 0-180° etc. Servo motor control is simple and needs no extra
drivers like stepper motor and only angular motion is possible. The angular position is
determined by the width of the pulse at the control input. Angular position can be controlled by
varying the pulse width between 1ms to 2ms.
Applying a pulse of appx 1ms pulse width will rotate the servo motor to 0 degree, a pulse of 1.5
ms pulse width will rotate the servo motor to 90 degrees and a pulse of 2 ms pulse width will
rotate the servo motor to 180 degrees.

Components/Terminals in Proteus: ATMEGA32, MOTOR-PWMSERVO, DC, GND

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 Embedded Systems Lab - 5047 Prepared by:
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Circuit Diagram:

Algorithm:

1. Set PORTC pin 0 as output by initializing DDRC register with 0x01.

2. In a continuous loop, first output a pulse of 1 ms duration to PORTC pin0. This will rotate
the motor to 0 degree.
3. Then after a small delay output a pulse of 1.5 ms duration to PORTC pin0. This will
rotate the motor to 90 degrees and after a small delay output a pulse of 2 ms duration
to PORTC pin0 which will rotate the motor to 180 degrees.

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 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Code:

#define F_CPU 1000000UL //1 MHz clock

#include <avr/io.h>
#include <util/delay.h>

int main(void)

DDRC = 0x01; //Makes RC0 output pin

PORTC = 0x00;
while(1)

//Rotate Motor to 0 degree by applying 1 ms pulse

PORTC = 0x01;
_delay_ms(1000);
PORTC = 0x00;

_delay_ms(2000);

//Rotate Motor to 90 degree by applying 1.5 ms pulse

PORTC = 0x01;
_delay_us(1500);
PORTC = 0x00;

_delay_ms(2000);

//Rotate Motor to 180 degree by applying 2 ms pulse

PORTC = 0x01;
_delay_ms(2000);
PORTC = 0x00;

_delay_ms(2000);

return 0;

Result:

Interfaced Servo motor with AVR microcontroller and observed the angle of rotation by
applying pulses of different widths.

For Office use only Signature of Lab in charge Remarks

Completion of Experiment

Dept. of Electronics Engg, GPTC Kottayam Page 40

 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Exp No. 8 Date: / /

Stepper Motor Interfacing with AVR

Aim:
To monitor the status of a switch and perform the following:
(a) If Switch is open, the Stepper motor rotates clockwise.
(b) If Switch is closed, the Stepper motor rotates counterclockwise.

Requirements:

PC running Windows XP or later version with AVR Studio and Proteus Installed.

Theory:

PORTA is configured as an input port and PORTC is configured as an output port. Switch is
connected to PORTA Pin 0. A Unipolar Stepper Motor is interfaced to AVR through ULN2003A
driver IC. Because the AVR lacks sufficient current to drive the stepper motor windings, we
must use a driver such as the ULN2003A to energize the stator. ULN2003A has an internal diode
to take care of back EMF. 4 Input pins (pin 1 to 4) of ULN2003A are connected to PORTC pins 0
to 3 respectively. Windings A, B, C and D of Stepper Motor are connected to 4 output pins (pin
1 to 4) of ULN2003A. ULN2003A IC is provided with separate 5V DC supply. 2 COM windings of
Stepper motor are connected to 12V DC.

Components/Terminals in Proteus: ATMEGA32, ULN2003A, MOTOR-STEPPER, RES, SWITCH,

DC, GND

Dept. of Electronics Engg, GPTC Kottayam Page 41

 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Circuit Diagram:

Algorithm:

1. Set PORTC as output by initializing DDRC register with 0xFF and PORTA as input by
initializing DDRA register with 0x00
2. In a continuous loop, read the status of switch by reading value of PORTA Pin 0. If it is
low(Switch is closed), output the sequence 0x66, 0xCC, 0x99 and 0x33 to PORTC in order
with a delay of 100ms between each sequence.
3. If it is high (Switch is open), output the sequence 0x66, 0x33, 0x99 and 0xCC to PORTC in
order with a delay of 100ms between each sequence.

Dept. of Electronics Engg, GPTC Kottayam Page 42

 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Code:

#define F_CPU 1000000UL //1 MHz clock

#include <avr/io.h>
#include <util/delay.h>

int main(void)

DDRA = 0;
DDRC = 0xFF;

while(1)

if ((PINA & 0x01) == 0)

PORTC = 0x66;
_delay_ms(100);
PORTC = 0xCC;
_delay_ms(100);
PORTC = 0x99;
_delay_ms(100);
PORTC = 0x33;
_delay_ms(100);

else

PORTC = 0x66;
_delay_ms(100);
PORTC = 0x33;
_delay_ms(100);
PORTC = 0x99;
_delay_ms(100);
PORTC = 0xCC;
_delay_ms(100);

return 0;

Result:

Interfaced Stepper motor with AVR microcontroller using ULN2003A motor driver and using a
switch controlled the direction of rotation.

For Office use only Signature of Lab in charge Remarks

Completion of Experiment

Dept. of Electronics Engg, GPTC Kottayam Page 43

 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Exp No. 9 Date: / /

Seven segment display interface with AVR

Aim:

To interface a seven segment display with AVR microcontroller

Requirements:

PC running Windows XP or later version with AVR Studio and Proteus Installed.

Theory:

PORTC is configured output port. A common cathode 7 segment relay is connected to PORTC.
Port C Pins 0 to 6 are connected to D1 to D7 segment pins of 7 segment display which
correspond to segments a to g in 7 segment display. Digits 0 to 9 are displayed with 1s delay by
turning ON the appropriate segments of 7 segment display.

Components/Terminals in Proteus: ATMEGA32, 7SEG-COM-CATHODE

Dept. of Electronics Engg, GPTC Kottayam Page 44

 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Circuit Diagram

Algorithm:

1. Set PORTC as output by initializing DDRC register with 0xFF

2. 8 bit hex codes to display digits 0 to 9 in 7 segment display are stored in an array. The
program loops through the array continuously and outputs the code to PORTC.

Dept. of Electronics Engg, GPTC Kottayam Page 45

 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Code:
#define F_CPU 1000000UL //1 MHz clock
#include <avr/io.h>
#include <util/delay.h>

char seg_7[10] = {0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x6F};

int main(void)
{
DDRC = 0xFF; //port C is output
PORTC = 0x00;
int i= 0;
while(1)
{
PORTC = seg_7[i];
_delay_ms(1000);
i+=1;
if(i>=10)
{
i=0;
}
}
return 0;
}

Result:

7 segment display has been interfaced and digits 0 to 9 displayed continuously.

For Office use only Signature of Lab in charge Remarks

Completion of Experiment

Dept. of Electronics Engg, GPTC Kottayam Page 46

 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Exp No. 10 Date: / /

DAC interfacing with AVR

Aim:

To interface DAC0808 IC with AVR microcontroller

Requirements:

PC running Windows XP or later version with AVR Studio and Proteus Installed.

Theory:

In DAC0808, the digital inputs are converted to current (Iout), and by connecting a resistor to
the Iout pin, we convert the result to voltage. Iref current output is isolated by connecting it to
an op-amp such as the 741. PORTD is configured as an output port. 8 digital input pins A1 to A8
of DAC0808 are connected to PORT. 12V DC is connected to VREF+ pin of DAC0808 and -12V DC
is connected to VEE pin of DAC0808. 741 Op Amp is configured as a I to V converter.

Components/Terminals in Proteus: ATMEGA32, 741, DAC0808, CAP, RES, DC, GND,

OSCILLOSCOPE

Dept. of Electronics Engg, GPTC Kottayam Page 47

 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Circuit Diagram:

Algorithm:

1. Set PORTD as output by initializing DDRD register with 0xFF.

2. Increment PORTD values from 0x00 to 0xFF continuously with steps of 0x01 with a delay
of 100us between each step.
3. Observe the Ramp output on Oscilloscope.

Dept. of Electronics Engg, GPTC Kottayam Page 48

 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Code:

#define F_CPU 1000000UL //1 MHz clock

#include <avr/io.h>
#include <util/delay.h>

int main(void)
{
unsigned char i = 0;
DDRD = 0xFF;
while(1)
{
PORTD = i;
_delay_us(100); //for oscilloscope ramp display
//_delay_ms(200); //for DC voltmeter display
i++;
}
return 0;
}

Result:

Interfaced DAC0808 with ATMEGA32 and observed the following Ramp Waveform on
Oscilloscope

Dept. of Electronics Engg, GPTC Kottayam Page 49

 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

For Office use only Signature of Lab in charge Remarks

Completion of Experiment

Dept. of Electronics Engg, GPTC Kottayam Page 50

 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Exp No. 11 Date: / /

ADC interfacing using I2C

Aim: To interface ADC module PCF8591 with AVR and display binary data

Requirements:

PC running Windows XP or later version with AVR Studio and Proteus Installed.

Theory:

The PCF8591 is a single-chip, single-supply low power 8-bit CMOS data acquisition device with
four analog inputs, one analog output and a serial I2C-bus interface. Three address pins AO, A1
and A2 are used for programming the hardware address. Address, control and data to and from
the device are transferred serially via the two-line bidirectional I2C bus.
SCL and SDA pins of PCF8591 are connected to the SCL and SDA pins of ATmega32. LM34
Temperature sensor is connected to Analog Input pin AIN0. A0,A1,A2 are grounded to make
device address as 000.
VREF pin of PCF8591 is provided with 2.56V either directly through a DC source or through a
potentiometer. AGND pin is grounded. PCF8591 is configured as an ADC and has 8-bit
resolution. So the number of steps will be 256. The step size is calculated as (VREF – AGND)/256
= (2.56 V – 0 V)/256 = 10 mV. LM34 sensor produces 10 mV for each degree of temperature
change and the ADC step size is also 10 mV. So each degree of temperature change
corresponds to 1 ADC step. So the binary output of the ADC directly corresponds to the real
temperature.
An A/D conversion cycle is always started after sending a valid read mode address to a PCF8591
device. Once a conversion cycle is triggered an input voltage sample of the selected channel is
stored on the chip and is converted to the corresponding 8-bit binary code. The conversion
result is stored in the ADC data register and awaits transmission.

Components/Terminals in Proteus: ATMEGA32, PCF8591, LM34, LED-RED, RES, DC, GND

Dept. of Electronics Engg, GPTC Kottayam Page 51

 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Circuit Diagram:

Algorithm:

1. Call i2c_init() function which initializes I2C communication module of ATmega32 and
then call i2c_start() function which is used to set start condition and initiate an I2C
communication,
2. i2c_write() function is called with 0x90 which is the address of PCF8591 (1001000) and 0
in LSB which corresponds to write mode.
3. i2c_write() function is called with 0x00 to select single ended input channel 0 AIN0.
4. In a continuous loop first call i2c_start() function and then call i2c_write() function with
0x91 which is the address of PCF8591 (1001000) and 1 in LSB which corresponds to
read mode.
5. i2c_read_ack() function is then called to read a byte from PCF8591 device with
acknowledgement, which is fetched to the TWDR register in ATmega32. This function
returns the TWDR value which is the value read from PCF8591.
6. Then i2c_read_no_ack() function is called to read a byte from PCF8591 device with NO
acknowledgement, which is fetched to the TWDR register in ATmega32. This function

Dept. of Electronics Engg, GPTC Kottayam Page 52

 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

returns the TWDR value which is the value read from PCF8591 and is stored in a variable
temp.
7. PORT D is configured as output by writing 0xFF in DDRD. 8 LEDs are connected to
PORTD.
8. The digital value read from PCF8591 is written to PORTD, and the LEDs connected to
PORTD show the digital value.

Code:
#define F_CPU 1000000UL //1 MHz clock
#include <avr/io.h>
#include <util/delay.h>

void i2c_init(void)
{
TWSR = 0x00; //set pre-scaler bits to 0
TWBR = 0x47; //set SCL freq = CPU freq/(16+(2*71))
TWCR = 0x04; //enable TWI
}

void i2c_start(void)
{
TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN); //set TWI interrupt, generate START
//condition & TWI enable
while((TWCR & (1<<TWINT)) == 0); //wait till TWINT bit in TWCR is set to 1 after
//successful TWI operation
}

void i2c_write(unsigned char data)

{
TWDR = data;
TWCR = (1<<TWINT) | (1<<TWEN); //set TWI interrupt & TWI enable
while((TWCR & (1<<TWINT)) == 0); //wait till TWINT bit in TWCR is set to 1 after
//successful TWI operation
}

void i2c_stop(void)
{
TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO); //set TWI interrupt,TWI enable
//& generate STOP condition.
for (int k = 0; k<100; k++) //To add a small delay.
{

}
}

unsigned char i2c_read_ack(void)

{
TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA);
while((TWCR & (1<<TWINT)) == 0); //wait till TWINT bit in TWCR is set to 1
//after successful TWI operation
return TWDR;
}

Dept. of Electronics Engg, GPTC Kottayam Page 53

 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

unsigned char i2c_read_no_ack(void)

{
TWCR = (1<<TWINT) | (1<<TWEN);
while((TWCR & (1<<TWINT)) == 0); //wait till TWINT bit in TWCR is set to 1
//after successful TWI operation
return TWDR;
}

int main(void)
{
DDRD = 0xFF; //portD as output
i2c_init();
i2c_start();
i2c_write(0x90); //address of PCF8591 (1001000) + W(0)
i2c_write(0x00); //select single ended input channel 0 AIN0
i2c_stop();

unsigned char temp;

while(1)
{
i2c_start();
i2c_write(0x91); //address of PCF8591 (1001000) + R(1)
i2c_read_ack();
temp = i2c_read_no_ack();
i2c_stop();
PORTD = temp; //display digital value in led
}
return 0;
}

Result:

Interfaced PCF8591 module in ADC mode with ATmega32. LM34 temperature sensor IC was
connected to PCF8591 ADC module and observed the binary output from PCF8591
corresponding to the analog temperature value through LEDs connected to PORTD.

For Office use only Signature of Lab in charge Remarks

Completion of Experiment

Dept. of Electronics Engg, GPTC Kottayam Page 54

 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Date: / /

OPEN ENDED PROJECT

Dept. of Electronics Engg, GPTC Kottayam Page 55

 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Dept. of Electronics Engg, GPTC Kottayam Page 56

 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

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 Embedded Systems Lab - 5047 Prepared by:
Arjun P, Lr. in Electronics Engg

Dept. of Electronics Engg, GPTC Kottayam Page 58