#define F_CPU 16000000UL
#include <avr/io.h>
#include <util/delay.h>

int main(void)
{
  DDRB = 0b00100000;	
	
  while (1) 
  {
    PORTB = 0b00100000;
	_delay_ms(500);
	PORTB = 0b00000000;
	_delay_ms(500);
  }
}

