Download AVR Line Following Robot

AVR Line Following Robot
Priyank Patil, [email protected]
Block Diagram
The robot uses IR sensors to sense the line, an array of 8 IR LEDs (Tx) and sensors (Rx), facing
the ground has been used in this setup. The output of the sensors is an analog signal which
depends on the amount of light reflected back, this analog signal is given to the comparator to
produce 0s and 1s which are then fed to the µC.
L4
L3
L2
Left
L1 R1 R2
Center
Sensor Array
R3
R4
Right
Starting from the center, the sensors on the left are named L1, L2, L3, L4 and those on the right
are named R1, R2, R3, R4.
Let us assume that when a sensor is on the line it reads 0 and when it is off the line it reads 1
The µC decides the next move so as to position the robot such that L1 and R1 both read 0 and the
rest read 1.
L4
1
Left
L3
1
L2
1
L1 R1 R2 R3 R4
0
0
1
1
1
Center
Right
Desired State L1=R1=0, and Rest=1
Algorithm:
1.
L= leftmost sensor which reads 0; R= rightmost sensor which reads 0.
If no sensor on Left (or Right) is 0 then L (or R) equals 0;
For example:
L4
1
L3
0
L2
0
Left
R2
1
Here L=3 R=0
L2 L1 R1 R2
0
0
0
0
Left
Center
Here L=2 R=4
If all sensors read 1 go to step 3,
else,
If L>R Move Left
If L<R Move Right
If L=R Move Forward
Go to step 4
L4
1
2.
L1 R1
1
1
Center
L3
1
R3
1
R4
1
Right
R3
0
3.
Move Clockwise if line was last seen on Right
Move Counter Clockwise if line was last seen on Left
Repeat step 3 till line is found.
4.
Go to step 1.
R4
0
Right
Sensor Circuit
For a good voltage swing from the potential divider use
R1= Sqrt (Resistance of sensor when light falls on it * Resistance of sensor when light does not fall on it)
Motor Interface and Control Circuit:
The 8 sensors are connected to PORTA.
You need not connect anything to AVCC and AREF, it is required only if ADC is used.
The L298 Motor Driver has 4 inputs to control the motion of the motors and two enable inputs
which are used for switching the motors on and off. To control the speed of the motors a PWM
waveform with variable duty cycle is applied to the enable pins. Rapidly switching the voltage
between Vs and GND gives an effective voltage between Vs and GND whose value depends on
the duty cycle of PWM. 100% duty cycle corresponds to voltage equal to Vs, 50 % corresponds
to 0.5Vs and so on. The 1N4004 diodes are used to prevent back EMF of the motors from
disturbing the remaining circuit.
You may drop your feedback at [email protected]
Download:
Source code: Lfsource.c
Complete Document: AVR Line Follwing Robot
/*****************************************************
Project : Line Follower
Version :
Date
: 2/19/2006
Author : Priyank
Company : Home
Compiler: CodeVision AVR
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
#define
#define
#define
#define
#define
#define
#define
#define
#define
#define
#define
#define
#define
#define
#define
FWD 0xAA
REV 0x55
R 0x22
L 0x88
CW 0x99
CCW 0x66
STOP 0x00
B 0xFF
RSPEED OCR1AL
LSPEED OCR1BL
SPEED0 255
SPEED1 0
SPEED2 0
SPEED3 0
MAX 7
HMAX 3
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
// 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);
}