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

// LCD I2C address 0x27 (ubah jika berbeda)
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Pin deklarasi
const int mq2Pin = 34;     // Input analog MQ2
const int ledMerah = 27;
const int ledHijau = 26;
const int buzzer = 25;

void setup() {
  Serial.begin(115200);
  pinMode(ledMerah, OUTPUT);
  pinMode(ledHijau, OUTPUT);
  pinMode(buzzer, OUTPUT);

  lcd.init();
  lcd.backlight();

  lcd.setCursor(0, 0);
  lcd.print("MQ2 Gas Sensor");
  delay(2000);
  lcd.clear();
}

void loop() {
  int gasValue = analogRead(mq2Pin);
  Serial.print("Gas Value: ");
  Serial.println(gasValue);

  lcd.setCursor(0, 0);
  lcd.print("Gas: ");
  lcd.print(gasValue);
  lcd.print("     ");

  // Ambang batas gas (ubah sesuai kebutuhan)
  if (gasValue > 600) {
    digitalWrite(ledMerah, HIGH);
    digitalWrite(ledHijau, LOW);
    digitalWrite(buzzer, HIGH);
    lcd.setCursor(0, 1);
    lcd.print("Bahaya! Gas tinggi");
  } else {
    digitalWrite(ledMerah, LOW);
    digitalWrite(ledHijau, HIGH);
    digitalWrite(buzzer, LOW);
    lcd.setCursor(0, 1);
    lcd.print("Aman               ");
  }

  delay(500);
}