#include <Servo.h>

#define TRIG_PIN 2
#define ECHO_PIN 3
#define BUZZER_PIN 5
#define SERVO_PIN 9

Servo palang;

long duration;
int distance;
bool isOpen = false; // status palang

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

  palang.attach(SERVO_PIN);
  palang.write(0); // posisi awal tertutup
}

void loop() {
  // Kirim pulsa trigger
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  // Baca echo
  duration = pulseIn(ECHO_PIN, HIGH);
  distance = duration * 0.034 / 2; // konversi cm

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

  if (distance > 0 && distance < 100) {
    if (!isOpen) {
      // Jika palang baru dibuka
      palang.write(90);           
      Serial.println("Palang Terbuka");
      
      // Bunyi buzzer 2 detik
      digitalWrite(BUZZER_PIN, HIGH);
      delay(2000);
      digitalWrite(BUZZER_PIN, LOW);

      isOpen = true;
    }
  } else {
    if (isOpen) {
      // Jika palang baru ditutup
      palang.write(0);
      Serial.println("Palang Tertutup");
      isOpen = false;
    }
  }

  delay(200);
}