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

int main ()
{
	DDRB |= 0x20;		

	OCR0 = 40;		
	TCCR0 = 0x09;		

	TIMSK = (1<<OCIE0);	
	sei ();			

	DDRC = 0x00;		
	DDRD = 0xFF;		

	while (1)			
		PORTD = PINC;	
}

ISR (TIMER0_COMP_vect)		
{
	PORTB ^= 0x20;		
}