#include <wiringPi.h>
int pin = 3;
void blink() {
  digitalWrite (pin, HIGH);
  delay (500);
  digitalWrite (pin,  LOW);
  delay (500);
}

int main (void)
{
  wiringPiSetup ();
  pinMode (pin, OUTPUT);
  for (;;) {
    blink();
  }
  return 0 ;
}