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

#define MQ2_PIN 34
#define BUZZER_PIN 26

LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  Serial.begin(115200);

  pinMode(BUZZER_PIN, OUTPUT);
  digitalWrite(BUZZER_PIN, LOW);

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

  lcd.setCursor(0, 0);
  lcd.print("Gas Monitoring");
  lcd.setCursor(0, 1);
  lcd.print("System Ready");
  delay(2000);
  lcd.clear();
}

void loop() {

  int gasValue = analogRead(MQ2_PIN);

  Serial.print("Gas Value: ");
  Serial.println(gasValue);

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

  if (gasValue > 2000) {

    lcd.setCursor(0, 1);
    lcd.print("GAS DETECTED!");

    digitalWrite(BUZZER_PIN, HIGH);

  } else {

    lcd.setCursor(0, 1);
    lcd.print("Air Normal");

    digitalWrite(BUZZER_PIN, LOW);
  }

  delay(500);
}