timer.c

/*
 * timer.c
 *
 * Created: 2/16/2016 2:55:03 PM
 * Author : shuffleres
 */ 

#include <avr/io.h>
#include <avr/interrupt.h>

void init_timer_0();

volatile int counter = 500;

int main(void)
{
    /* Replace with your application code */
	DDRB = 0x80;
	PORTB = 0x0;
	init_timer_0();
    while (1) 
    {
		//
    }
}

void init_timer_0() {
	TCCR0A = 0X02;
	OCR0A = 0XFA;
	TIMSK0 = 0X02;
	TCCR0B = 0x03;
	sei();
}


ISR(TIMER0_COMPA_vect) {
	counter--;
	if (counter <= 0) {
		counter = 500;
		PORTB ^= 0X80;
	}
}