void setup() {
  // put your setup code here, to run once:
  volatile char *dir=0x30;
  volatile char *out=0x31;
  volatile long i;
  *dir=0b00000001;//1
  while(1)
  {
    *out=0b00000001;
    for(i=0;i<2000;i++);//delay 
    *out=0b00000000;
    for(i=0;i<2;i++);//delay
  }
}

void loop() {
  // put your main code here, to run repeatedly:

}