/************************************************
MIT Solar Electric Vehicle Team
Michael Seeman '04

AVR Sample Code : Blink LED with Timer

-- sample.c --

Created: 9/30/02
Last Modified: 10/7/02
************************************************/

#include <avr/io.h>
#include <avr/signal.h>
#include <avr/interrupt.h>
#include "sample.h"

/* global variable definitions */

/* volatile means value can change without explicit assignment */
volatile unsigned char  timer_step = 0;

int main (void)
{
  // char    error = 0;

  /* Initialize port directions */
  DDRA = port_a_io;
  DDRB = port_b_io;
  DDRC = port_c_io;
  DDRD = port_d_io;

  /* Initialize timer */
  timer_init();
  /* Enable interrupts */
  sei();
  
  /* Define local variables */
  unsigned char  save=0;
  char state=0;

  /* do an infinite loop */
  for (;;) {
    /* check to see if 8 timer_step ticks have elapsed (about .5 sec) */
    if (((unsigned char)(timer_step - save)) > 8) {
      /* reset save */
      save = timer_step;
      /* toggle state of LED */
      if (state) {
	PORTD &= ~(1<<io_led_heartbeat); // clear heartbeat pin
	state=0;
      } else {
	PORTD |= (1<<io_led_heartbeat);
	state=1;
      }
    }
  }
  /* note: the AVR doesn't like falling off the end of the program
     thus, it is good to have an infinite loop somewhere in your code */
}