#define F_CPU 1000000UL

#include <avr/io.h>
#include <util/delay.h>

int main(void)
{
          /* enable pin as output by setting the data direction register */
          DDRC|= (1<<DDC5);

          while (1) {
                      /* led on, pin=0 */
                      PORTC &= ~(1<<PORTC5);
                      _delay_ms(5000);
                      /* set output to 5V, LED off */
                      PORTC|= (1<<PORTC5);
                      _delay_ms(5000);
          }
          return(0);
}