/*This program is used to test stepper motor*/
#include <mega32.h>     
#include <stdio.h>
#include <stdlib.h>

#define begin {
#define end }

// Declare your global variables here
unsigned char count,reload,step,stop;
unsigned int time0;
   
//**********************************************************
//timer 0 overflow ISR
interrupt [TIM0_OVF] void timer0_overflow(void)
begin
   //reload to force 1 mSec overflow
   TCNT0=reload;
   //clear the flag, task1 should be executed
   time0++;
end   
     
//**********************************************************
void initialize(void)
{    	
	DDRA=0xff;
	PORTA=0xff;
	
	//output LED
	DDRB=0xff;
    PORTB=0x00;
                  
 	DDRD=0xff;
 	PORTD=0x00;
	

	//timer0 is used to control the turning speed
	time0=0;
	reload=256-125;
	TCCR0=0x03 ;
	TCNT0=reload;
	TIMSK=1;
	OCR0=0x00;
    stop=0;    
    count=1;
    #asm
      	sei
    #endasm

}               

void leftsteer(void)
{   

	time0=0;  
	step=0;
	while (step<4) 	//we can change number of steps the motor turns
    {
   
       	if (time0==2000) //to clearly see the step, we put delays to the program
       	{     
       		if (count==4) count=1;
     		else count++;
       
           
	 		if (count==1) PORTA=0b00001010;
      		else if (count==2) PORTA=0b00101000;
  		    else if (count==3) PORTA=0b10100000;
  		    else if (count==4) PORTA=0b10000010;	 
   
   			step++;
   			time0=0;
         
        } 
	 }
}    

void rightsteer(void)
{   //same as leftsteer except the sequence is reversed 

	time0=0; 
	step =0;
	while (step<4) 
    {
   
       	if (time0==2000) 
       	{     
     		if (count==1) count=4;
     		else count--;
         
	 		if (count==1) PORTA=0b00001010;
      		else if (count==2) PORTA=0b00101000;
      		else if (count==3) PORTA=0b10100000;
      		else if (count==4) PORTA=0b10000001;	 
          	step++;
   			time0=0;
   
     	} 
    }
} 

void main(void)
{
      initialize();    
      count=1;
      while (1)
      { 
        	//perform 1 left turn and 1 right turn  	      
    		if (stop!=1) 
    		{ 
				leftsteer();
    	  		rightsteer();
    	  		stop=1;
      		}
      }
                
}