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

LiquidCrystal_I2C lcd(0x27, 16, 2); // Ubah 0x27 jika LCD tidak nyala

// Pin
#define MQ2_PIN A0
#define LED_HIJAU 2
#define LED_MERAH 3
#define BUZZER 4

// Ambang batas gas (sesuaikan)
int batasGas = 300;

void setup() {
  pinMode(MQ2_PIN, INPUT);
    pinMode(LED_HIJAU, OUTPUT);
      pinMode(LED_MERAH, OUTPUT);
        pinMode(BUZZER, OUTPUT);

          lcd.init();
            lcd.backlight();
              lcd.setCursor(0, 0);
                lcd.print("Deteksi Gas");
                  lcd.setCursor(0, 1);
                    lcd.print("Initializing...");
                      delay(2000);
                        lcd.clear();
                        }

                        void loop() {
                          int nilaiGas = analogRead(MQ2_PIN);

                            if (nilaiGas > batasGas) {
                                // Gas terdeteksi
                                    digitalWrite(LED_MERAH, HIGH);
                                        digitalWrite(LED_HIJAU, LOW);
                                            tone(BUZZER, 1000); // Buzzer bunyi

                                                lcd.setCursor(0, 0);
                                                    lcd.print("!!! BAHAYA !!! ");
                                                        lcd.setCursor(0, 1);
                                                            lcd.print("Gas Terdeteksi ");
                                                              } 
                                                                else {
                                                                    // Aman
                                                                        digitalWrite(LED_MERAH, LOW);
                                                                            digitalWrite(LED_HIJAU, HIGH);
                                                                                noTone(BUZZER); // Matikan buzzer

                                                                                    lcd.setCursor(0, 0);
                                                                                        lcd.print("Aman           ");
                                                                                            lcd.setCursor(0, 1);
                                                                                                lcd.print("Tidak Terdeteksi");
                                                                                                  }

                                                                                                    delay(500);
                                                                                                    }