AVR Line Follower - Page 3

Source Code:

/***
Project : Line Follower
Version :
Date :
Comments:
Chip type : ATmega16
Program type : Application
Clock frequency : 7.372800 MHz
Memory model : Small
External SRAM size : 0
Data Stack size : 256
***/
//#define debug 1
#include <mega16.h>
#include <delay.h>
#ifdef debug
#include <stdio.h>
#endif
#define FWD 0xAA
#define REV 0x55
#define R 0x22
#define L 0x88
#define CW 0x99
#define CCW 0x66
#define STOP 0x00
#define B 0xFF
#define RSPEED OCR1AL
#define LSPEED OCR1BL
#define SPEED0 255
#define SPEED1 0
#define SPEED2 0
#define SPEED3 0
#define MAX 3
#define HMAX 1
void move (unsigned char dir,unsigned char delay,unsigned char power);
unsigned char i,rdev,ldev,ip,delay,dir,power,dirl,history[MAX],hcount=0,rotpow;
#ifdef debug
unsigned char rep=0,prev=0;
#endif
void main(void)
{
// Input/Output Ports initialization
// Port A initialization
// Func7=In Func6=In Func5=In Func4=In Func3=In Func2=In Func1=In Func0=In
Line Follower
Page 12 of 17
// State7=T State6=T State5=T State4=T State3=T State2=T State1=T State0=T
PORTA=0x00;
DDRA=0x00;
// Port B initialization
// Func7=In Func6=In Func5=In Func4=In Func3=In Func2=In Func1=In Func0=In
// State7=T State6=T State5=T State4=T State3=T State2=T State1=T State0=T
PORTB=0x00;
DDRB=0x00;
// Port C initialization
// Func7=In Func6=In Func5=In Func4=In Func3=In Func2=In Func1=In Func0=In
// State7=T State6=T State5=T State4=T State3=T State2=T State1=T State0=T
PORTC=0x00;
DDRC=0xFF;
// Port D initialization
// Func7=In Func6=In Func5=Out Func4=Out Func3=In Func2=In Func1=In Func0=In
// State7=T State6=T State5=0 State4=0 State3=T State2=T State1=T State0=T
PORTD=0x00;
DDRD=0x30;
// Timer/Counter 0 initialization
// Clock source: System Clock
// Clock value: Timer 0 Stopped
// Mode: Normal top=FFh
// OC0 output: Disconnected
TCCR0=0x00;
TCNT0=0x00;
OCR0=0x00;
// Timer/Counter 1 initialization
// Clock source: System Clock
// Clock value: 921.600 kHz
// Mode: Fast PWM top=00FFh
// OC1A output: Non-Inv.
// OC1B output: Non-Inv.
// Noise Canceler: Off
// Input Capture on Falling Edge
TCCR1A=0xA1;
TCCR1B=0x0A;
TCNT1H=0x00;
TCNT1L=0x00;
ICR1H=0x00;
ICR1L=0x00;
OCR1AH=0x00;
OCR1AL=0xFF;
OCR1BH=0x00;
OCR1BL=0xFF;
// Timer/Counter 2 initialization
// Clock source: System Clock
// Clock value: Timer 2 Stopped
// Mode: Normal top=FFh
// OC2 output: Disconnected
ASSR=0x00;
TCCR2=0x00;
TCNT2=0x00;
OCR2=0x00;
// External Interrupt(s) initialization
// INT0: Off
// INT1: Off
// INT2: Off
MCUCR=0x00;
MCUCSR=0x00;
#ifdef debug
// USART initialization
// Communication Parameters: 8 Data, 1 Stop, No Parity
// USART Receiver: On
// USART Transmitter: On
// USART Mode: Asynchronous
// USART Baud rate: 57600
UCSRA=0x00;
UCSRB=0x18;
UCSRC=0x86;
UBRRH=0x00;
UBRRL=0x07;
#endif
// Timer(s)/Counter(s) Interrupt(s) initialization
TIMSK=0x00;
// Analog Comparator initialization
// Analog Comparator: Off
// Analog Comparator Input Capture by Timer/Counter 1: Off
ACSR=0x80;
SFIOR=0x00;
while (1){
#ifdef debug
if(rep<255)
rep++;
if(prev!=PINA) {
prev=PINA;
printf("%u\r",rep);
for(i=0;i<8;i++)
printf("%u\t",(prev>>i)&0x01);
rep=0;
}
#endif
if(PINA!=255){
rotpow=255;
ldev=rdev=0;
if(PINA.3==0)
rdev=1;
if(PINA.2==0)
rdev=2;
if(PINA.1==0)
rdev=3;
if(PINA.0==0)
rdev=4;
if(PINA.4==0)
ldev=1;
if(PINA.5==0)
ldev=2;
if(PINA.6==0)
ldev=3;
if(PINA.7==0)
ldev=4;
if(rdev>ldev)
move(R,0,195+12*rdev);
if(rdev<ldev)
move(L,0,195+12*ldev);
if(rdev==ldev)
move(FWD,0,200);
}
else {
for(i=0,dirl=0;i<MAX;i++) {
if(history[i]==L)
{dirl++;}
}
if(rotpow<160) {rotpow=160;}
if(rotpow<255) {rotpow++;}
if(dirl>HMAX)
{move(CW,0,rotpow);}
else
{move(CCW,0,rotpow);}
}
};
}
void move (unsigned char dir,unsigned char delay,unsigned char power) {
PORTC=dir;
if(dir==L || dir==R) {
hcount=(hcount+1)%MAX;
history[hcount]=dir;
}
LSPEED=RSPEED=255;//power;
//delay_ms(delay);
}

 

Possible Improvements:

  • Use of differential steering with gradual change in wheel speeds.
  • Use of Hysteresis in sensor circuit using LM339
  • Use of ADC so that the exact position of the line can be interpolated
  • Use of Wheel Chair or three wheel drive to reduce traction.
  • General improvements like using a low dropout voltage regulator, lighter chassis etc