AVR (Atmega8) & Temperature Controlled fan

1. PRESENTATION
ON
EMBEDDED SYSTEM
 BY
 Abhijit Das
 Course-B.Tech, Branch- ECE, 3rd Year
 Roll-13104076, NIT Jalandhar
Training Centre – SKYPHI TECHNOLOGIES
Malviya Nagar , Jaipur

2. About Organisation :
 Skyphi Technologies is a Renowned Training and Development
Organization in the field of Software Development, Mobile
Application Development, Web Development, well known for
providing quality education in advance domains such
as iPhone Training, Android Training, Java Training, Dot Net
Training, PHP Training, Oracle Training, Linux Training, SEO
Training, C Training, Embedded System Training, VLSI
Training, Robotics Training, MATLAB Training, Ethical Hacking
Training etc.

3. What Is
Embedded System ?

4. DEFINATION :
1. An Embedded System employs a combination of
hardware & software to perform a specific function.
2. Software is used for providing features and flexibility
hardware(Processors, Memory...) is used for
performance & sometimes security.
3. Embedded systems are often mass produced, so the cost
savings may be multiplied by millions of items.
4. The core of any embedded system is formed by one or
several microprocessor or micro controller programmed
to perform a small number of tasks.

5. Example of Embedded System :-
 1.Automated tiller machines (ATMS).
 2. Integrated system in aircraft and missile.
 3.Computer printers, Copiers.
 4. Disk drives (floppy disk drive and hard disk drive)
 5.Microprocessor (MPU) .
 6. Multimedia appliances: internet radio receivers, TV set
top boxes.
 7. Small hand held computer with P1M5 and other
applications.

6. Introduction to AVR

7. Features of AVR (ATMEGA-8) :
 RISC Architecture.
 8 bit Microcontroller
 High performance - 16MIPS @ 16MHz
 Large program memory
 EEPROM – non volatile memory
 Two 8 bit, One 16 bit timer with total 4 PWM channels
 On chip 10 bit ADC, 8 channels
 UART, I2C, SPI protocol support

8. TOOLS :
 Compiler : WinAVR/AVR Studio/CodeVision AVR
 The programmer hardware
 Simple parallel/serial port based In System
Programmer (ISP) or
 USB based ISP (recommended) : USBasp
 Bread board, wires, power supply, crystal, etc.

9. PIN DIAGRAM ATMEGA-8 :

10. EMBEDED C :
 Ebedded C is a nothing but a subset of c language is
compatiable with certain microcontrollers.
 some features are added some header files like
 <avr/io.h>,<util/delay.h>
 scanf() and printf() are removed as the inputs are
scanned from the sensorsand output are given to the ports.
 control structure remain the same like
if statement ,for loop,do while etc.

11. Structure of a c program for an
embedded system :
*//headers
#include<avr/io.h //header filefor AVR i/o
#include<util/delay.h> //header file for delay
*// main program
* int main()
{
* while(1)
{code………..]
*return(0);
}

12. I/O PORTS :
We have three ports
PORTB
PORTC
PORTD

13. THREE REGISTERS
Each port pin have three registers
1.DDRx :-Data direction register
2.PORTx:-data output
3.PINx :-port input

14. DDRx – Data Direction Register 
 Configures data direction of the port - Input / Output
 DDRx.n = 0 > makes corresponding port pin as input
 DDRx.n = 1 > makes corresponding port pin as output
 Examples :
 to make all pins of port A as input pins :
DDRA = 0b00000000;
 to make all pins of port A as output pins
DDRA = 0b11111111;
 to make lower nibble of port B as output and higher nibble as
input
DDRB = 0b00001111;

15. PORT Register 
For data output, when port is configured as output:
 Writing to PORTx.n will immediately (in same clock cycle)
change state of the port pins according to given value.
 Examples :
to output 0xFF data on PB
DDRB = 0b11111111; //set all pins of port
b as outputs
PORTB = 0xFF; //write data on port
to output data in variable x on PA
DDRA = 0xFF; //make port a as output
PORTA = x; //output 8 bit variable on
port

16. PIN Register 
 Used to read data from port pins, when port is
configured as input.
 First set DDRx to zero, then use PINx to read the
value.
 If PINx is read, when port is configured as output, it
will give you data that has been outputted on port.
 Example :
DDRA = 0x00; //Set PA as input
x = PINA; //Read contents of PA

17. TEMPERATURE CONTROLLED
FAN

18. Components Used 
AVR Board
Motor Driver(L293D)
LM35
DC Motor
Wheel

19. AVR Board
Motor Driver(L293D)
LM35 (Temperature Sensor)
DC Motor
Wheel

20. Working principle 
 1. Initially switch the power supply.
 2. Microcontroller starts reading the temperature of the surroundings.
 3. The analog value of temperature is given by the temperature sensor.
 4. This analog value is applied to the analog to digital converter pin of
the micro controller.
 5. This analog value is converted to the digital value by the
microcontroller using successive approximation method internally.
 6. When the temperature is greater than the threshold value,
microcontroller sends a command to the controller to switch the motor.
 7. Thus fan starts rotating.

21. CIRCUIT DIAGRAM 

22. Code 
void Initialize()
{
 FAN_POWER_LED_DDR|=0B10000000;
 POWER_LED_OFF();
 DDRC|=0b00111111; //Seven segment
 DDRB|=0b00000010; //Middle
segment G
 Display(0);

23.  void Display(uint8_t num)
 {
 if(num>9)
 return;
 switch (num)
 {
 case 0:
 PORTC=0B00000000;
 PORTB|=0B00000010
 void Display(uint8_t num)
 {
 if(num>9)
 return;
 switch (num)
 {
 case 0:
 PORTC=0B00000000;

24.  case 2:
 // xxfedcba
 PORTC=0B00100100;
 PORTB&=(~(0B00000010));
 break;
 case 3:
 // xxfedcba
 PORTC=0B00110000;
 PORTB&=(~(0B00000010));
 break;
 break;

25.  PORTC=0B00011001;
 PORTB&=(~(0B00000010));
 break;
 case 5:
 // xxfedcba
 PORTC=0B00010010;
 PORTB&=(~(0B00000010));

26.  if(cmd==RC_ENTER)
 {
 if(fan_on)
 {
 POWER_LED_OFF();
 fan_on=0; //Turn Off
 }
 else
 {
 POWER_LED_ON();
 fan_on=1; //Turn On
 }
 }
 Display(speed);
 }

27. Application :
This can be used in home
applications.
 The circuit can be used in CPU
to reduce the heat .

28. THANK YOU