const int trigPin = 9;
const int echoPin = 10;
const int buzzer = 8;

long duration;
int distance;

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

void loop() {
  // Kirim sinyal trigger ultrasonik
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Baca durasi echo
  duration = pulseIn(echoPin, HIGH);
  distance = duration * 0.034 / 2;

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

  // Cek dan kontrol buzzer
  if (distance > 0 && distance < 50) {
    Serial.println("Terlalu dekat! Buzzer ON");
    tone(buzzer, 1000); // buzzer aktif
  } else {
    Serial.println("Aman. Buzzer OFF");
    noTone(buzzer); // buzzer mati
  }

  delay(200);
}