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




void timer_init(void) {
    // wafeform generation mode bit, see page160
    // CTC Mode, TOP=OCR2A
    TCCR2A |= (1<<WGM21);
    // top value
    OCR2A = 15625;
    // set OC2A on compare match - from original code...useless?
    TCCR2A |= (1<<COM2A0) | (1<<COM2A1);

    // prescalar: 1024
    TCCR2B |= (1<<CS22) | (1<<CS21) | (1<<CS20);
    
    // if timer2 reaches the value in OCR2A, fire interrupt
    TIMSK2 |= (1<<OCIE2A);
}




#define LED1 PB0
ISR(TIMER2_COMPA_vect) {
    PORTB ^= (1 << LED1); // toggle LED1
}




int main (void) {
	timer_init();
	sei();

	for (;;) {
	}
}