#include "avr/io.h"
#include "avr/interrupt.h"

int main ()
{
	DDRB |= 0x20;		

	TCNT0 = -32;		
	TCCR0 = 0x01;		

	TIMSK = (1<<TOIE0);
	sei ();			

	DDRC = 0x00;	
	DDRD = 0xFF;	

	while (1)			
		PORTD = PINC;	
}

ISR (TIMER0_OVF_vect)	
{
	TCNT0 = -32;
	PORTB ^= 0x20;		
}