//ECE476 -- Alex Cerruti and Chris Wherry
//STEPTEST80.c -- tests operation of stepper motor
//rotates wheel counter-clockwise, clockwise, and reset
// with different buttons pushed.

#include <90S8515.h>
#include <delay.h>

//timeout values for each task
#define t1 25
#define t2 25

unsigned char reload;				//timer 0 reload to set 1 mSec
unsigned char time1;    			//timeout counters
unsigned char count;				//light states

//the three task subroutines
void task1(void);

void initialize(void); //all the usual mcu stuff

//**********************************************************
//timer 0 overflow ISR
interrupt [TIM0_OVF] void timer0_overflow(void)
  {
  //reload to force 1 mSec overflow
  TCNT0=reload;

  //Decrement the three times if they are not already zero
  if (time1>0)	--time1;

  }

//**********************************************************
//Entry point and task scheduler loop
void main(void)
  {
  initialize();

  //main task scheduler loop
  while(1)
    {
      if (time1==0)	task1();
      if (time2==0)	task2();    }
  }

//**********************************************************
//Task subroutines
//Task 1
void task1(void)
{
  time1=t1;  //reset the task timer
  if(PINB.0==0)
  {
    //make motor step forward twenty steps
    for(count=0; count<5; count++)
    {
	PORTA = 0x01;
        delay_ms(5);
	PORTA = 0x02;
        delay_ms(5);
	PORTA = 0x04;
        delay_ms(5);
	PORTA = 0x08;
        delay_ms(5);
    }
  }

  else if(PINB.1==0)
  {
    //make motor step backward twenty steps
    for(count=0; count<5; count++)
    {
	PORTA = 0x08;
        delay_ms(5);
	PORTA = 0x04;
        delay_ms(5);
	PORTA = 0x02;
        delay_ms(5);
	PORTA = 0x01;
        delay_ms(5);
    }
  }

  else if(PINB.2 == 0)
  {
    //make motor to reset position
    for(count=0; count<52; count++)
    {
	PORTA = 0x01;
        delay_ms(5);
	PORTA = 0x02;
        delay_ms(5);
	PORTA = 0x04;
        delay_ms(5);
	PORTA = 0x08;
        delay_ms(5);
    }
  }

  else
  {
  PORTA = 0x08;		//otherwise lock the colorwheel in place
  }
}

//**********************************************************
//Set it all up
void initialize(void)
{
//set up the ports
  DDRB=0x00;	//PORT D in an input
  DDRA=0xff;    // PORT A is an ouput
  PORTA=0x00;  	//PORT C is an output
  DDRC =0xff;
  PORTC = 0x00;

  reload=256-250; //value for 2 Msec for 8 MHz
  TCNT0=reload;
  TIMSK=2;  	  //turn on timer 0 overflow ISR (Mega pg. 30)
  TCCR0=3;	  //prescalar to 64

  //init the task timers
  time1=t1;

  //make motor to reset position
  for(count=0; count<52; count++)
  {
  PORTA = 0x01;
     delay_ms(5);
  PORTA = 0x02;
     delay_ms(5);
  PORTA = 0x04;
     delay_ms(5);
  PORTA = 0x08;
     delay_ms(5);
  }

  //crank up the ISRs
  #asm
  	sei
  #endasm
}