#define TRIG_PIN 9
#define ECHO_PIN 10
#define BUZZER_PIN 8

void setup() {
  Serial.begin(9600);
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(BUZZER_PIN, OUTPUT);
}

void loop() {
  long duration, distance;
  
  // Mengaktifkan sensor ultrasonik
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  
  duration = pulseIn(ECHO_PIN, HIGH);
  
  // Menghitung jarak
  distance = (duration * 0.034) / 2; // dalam cm
  
  Serial.print("Jarak: ");
  Serial.print(distance);
  Serial.println(" cm");
  
  // Deteksi objek dalam jarak tertentu
  if (distance < 20) { // Jarak deteksi 20 cm
    digitalWrite(BUZZER_PIN, HIGH); // Nyalakan buzzer
    delay(2000); // Buzzer berbunyi selama 2 detik
    digitalWrite(BUZZER_PIN, LOW); // Matikan buzzer
  }
  
  delay(500);
}