#include <Servo.h>

#define TRIGGER_PIN  9
#define ECHO_PIN     10
#define SERVO_PIN    11
#define MAX_DISTANCE 20

Servo servo;
bool isOpen = false;

void setup() {
  Serial.begin(9600);
  pinMode(TRIGGER_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  servo.attach(SERVO_PIN);
}

void loop() {
  long duration, distance;
  
  // Mengirim sinyal ultrasonik
  digitalWrite(TRIGGER_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIGGER_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIGGER_PIN, LOW);
  
  // Mengukur durasi dan menghitung jarak
  duration = pulseIn(ECHO_PIN, HIGH);
  distance = (duration / 2) / 29.1;

  // Validasi jarak
  if (distance < 0 || distance > MAX_DISTANCE) {
    distance = MAX_DISTANCE + 1; // Atur ke nilai yang lebih besar dari MAX_DISTANCE
  }

  // Kontrol servo berdasarkan jarak
  if (distance <= MAX_DISTANCE && !isOpen) {
    servo.write(90); // Buka tutup
    isOpen = true;
    delay(1000); // Tunggu selama 1 detik
  } else if (distance > MAX_DISTANCE && isOpen) {
    servo.write(0); // Tutup tutup
    isOpen = false;
  }

  // Menampilkan jarak di Serial Monitor
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");
  
  delay(100); // Tunggu sebelum pembacaan berikutnya
}