#include <avr/io.h>

#ifndef _BV
#define _BV(x) (1 << x)
#endif

#define F_CPU 16000000

int main(void){
  DDRD |= _BV(6);

  while(1){
    PORTD |= _BV(6);
    _delay_ms(1000);
    PORTD &= ~_BV(6);
    _delay_ms(1000);
  }
  return 0;
}