#define echoPin 2
#define trigPin 3

void setup() {
  Serial.begin(115200);
  pinMode(LED_BUILTIN, OUTPUT);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
}

float readDistance() {
  // Kirim trigger 10us
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Baca waktu pantulan
  long duration = pulseIn(echoPin, HIGH);

  // Konversi ke cm (kecepatan suara ~0.034 cm/us)
  float distance = duration * 0.034 / 2;
  return distance;
}

void loop() {
  float distance = readDistance();

  Serial.print("Jarak: ");
  Serial.print(distance);
  Serial.println(" cm");

  // Contoh: nyalakan LED jika objek dekat (< 10 cm)
  if (distance < 10) {
    digitalWrite(LED_BUILTIN, HIGH);
  } else {
    digitalWrite(LED_BUILTIN, LOW);
  }

  delay(500);
}