/*   Filename: TCNT0
Author:    Renier Del Rosario
Date:    10/5/2024
Description:  Timer Interrupt
*/

#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/pgmspace.h>
#include <util/delay.h>

#define TOGGLECYCLES 10

volatile unsigned char overflowCounter = 0;

int main(void)
{
  cli();                                //disable all interrupt
  DDRA = 0x80;                          // PORTA output
  PORTA = 0x00;                         // clear PORTA
  TCNT0 = 0x00;                         // clear the  timer
  TCCR0A = 0x00;                        // mode 0.
  TCCR0B = 0x03;                        // 64 prescaler

  TIMSK0 = TIMSK0 | (1 << TOIE0);       // Enables overflow interrupt
  TIFR0 = TIFR0 | (1 << TOV0);          // Set the overflow flag
  sei();                                // Enables all interrupts

  while(1);
  {
      ;
  }
  }

  ISR(TIMER0_OVF_vect)
  {
    if(overflowCounter == TOGGLECYCLES)
    {
      PORTA = PORTA ^ 0b10000000;
      overflowCounter = 0;
      // _delay_ms(500);
    }
    overflowCounter++;
    TIMSK0 = TIMSK0 | (1 << TOIE0);                   // re-arm interrupt
  }