#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// Atur alamat I2C (umumnya 0x27 atau 0x3F)
LiquidCrystal_I2C lcd(0x27, 16, 2);

int trigger_pin = 2;
int echo_pin = 3;
int buzzer_pin = 10;
int led_biru = 8;
int led_merah = 9;
long waktu;
int jarak;

void setup() {
  Serial.begin(9600);
  pinMode(trigger_pin, OUTPUT);
  pinMode(echo_pin, INPUT);
  pinMode(buzzer_pin, OUTPUT);
  pinMode(led_biru , OUTPUT);
  pinMode(led_merah, OUTPUT);

  // Inisialisasi LCD
  lcd.init();
  lcd.backlight();
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("Status Pintu:");
  delay(1000);
}

void loop() {
  // baca sensor ultrasonik
  digitalWrite(trigger_pin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigger_pin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigger_pin, LOW);

  waktu = pulseIn(echo_pin, HIGH);
  jarak = (waktu * 0.034) / 2;

  if (jarak >= 70) {
    Serial.println("Pintu Terbuka");
    digitalWrite(buzzer_pin, HIGH);
    digitalWrite(led_biru, HIGH);
    digitalWrite(led_merah, LOW);

    // tampilkan ke LCD
    lcd.clear();
    lcd.setCursor(0,0);
    lcd.print("Pintu Terbuka");
    lcd.setCursor(0,1);
    lcd.print("Jarak: ");
    lcd.print(jarak);
    lcd.print(" cm");
  } else {
    Serial.println("Pintu Tertutup");
    digitalWrite(buzzer_pin, LOW);
    digitalWrite(led_biru, LOW);
    digitalWrite(led_merah, HIGH);

    // tampilkan ke LCD
    lcd.clear();
    lcd.setCursor(0,0);
    lcd.print("Pintu Tertutup");
    lcd.setCursor(0,1);
    lcd.print("Jarak: ");
    lcd.print(jarak);
    lcd.print(" cm");
  }

  delay(300); // jeda supaya LCD tidak berkedip terlalu cepat
}