#include "avr/io.h"
#include "avr/interrupt.h"
ISR (TIMER1_OVF_vect)
{
	OCR1AH = 0;
	OCR1AL = ~OCR1AL;
}
int main ( )
{
	DDRD |= (1<<5);	
	OCR1AH = 0;	
	OCR1AL = 31;	
	TCCR1A = 0x81;	
	TCCR1B = 0x0A;	
	TIMSK = (1<<TOIE1);
	sei ( );
	while (1);
	return 0;
}