const int trigPin = 4;
const int echoPin = 2;
const int ledPin = 13;

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(ledPin, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  long duration;
  float distance;
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);
  distance = (duration / 2.0) / 29.41;

  if (distance < 0 || duration == 0) {
    Serial.println("Tidak terdeteksi");
    digitalWrite(ledPin, LOW);
  } else if (distance >= 300) {
    Serial.println("Diluar jangkauan");
    digitalWrite(ledPin, HIGH);
  } else {
    Serial.print("Jarak: ");
    Serial.print(distance);
    Serial.println(" cm");
    digitalWrite(ledPin, LOW);
  }

  delay(500);
}