const int trigPin = 9;  // pin trigger sensor ultrasonik
const int echoPin = 10;  // pin echo sensor ultrasonik
const int ledPin = 13;  // pin LED

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

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

  duration = pulseIn(echoPin, HIGH);
  distance = duration * 0.034 / 2;  // menghitung jarak dengan rumus dari datasheet
  Serial.print("Jarak : ");
  Serial.print(distance);
  Serial.println(" cm");
  
  if(distance < 10) {  // jika jarak kurang dari 10 cm
    digitalWrite(ledPin, HIGH);  // nyalakan LED
  } else {
    digitalWrite(ledPin, LOW);   // matikan LED
  }
  delay(500);  // tunggu selama 0,5 detik
}