void setup() {

  Serial.begin(9600);

  pinMode(EchoPin, INPUT);

  pinMode(TrigPin, OUTPUT);

}

void loop() {

  digitalWrite(TrigPin, LOW);

  delayMicroseconds(2);

  digitalWrite(TrigPin, HIGH);

  delayMicroseconds(10);

  digitalWrite(TrigPin, LOW);

  duration = pulseIn(EchoPin, HIGH);

  distance = duration / 58.00;

  Serial.print("Ultrasonic sensor: ");

  Serial.print(distance);

  Serial.println(" cm");

  delay(1000);

}

void setup() {

  pinMode(13, OUTPUT);

}

void loop() {

  int i = 0;

  while(1) {

    i++;

    if (i > 2) {

      digitalWrite(13, HIGH);

      delay(1000);

      i = 0;

    } else {

      digitalWrite(13, LOW);

      delay(1000);

    }

  }

}