#include <LiquidCrystal.h>

LiquidCrystal lcd(PB12, PB13, PB14, PB15, PA8, PA9);

#define GAS_SENSOR PA0
#define BUZZER PA5
#define THRESHOLD 2500

void setup()
{
  pinMode(GAS_SENSOR, INPUT_ANALOG);
  pinMode(BUZZER, OUTPUT);

  lcd.begin(16, 2);
  lcd.clear();

  lcd.setCursor(0, 0);
  lcd.print("SAFE FLAME");

  lcd.setCursor(0, 1);
  lcd.print("SYSTEM READY");

  delay(2000);
  lcd.clear();
}

void loop()
{
  int gasValue = analogRead(GAS_SENSOR);

  if (gasValue >= THRESHOLD)
  {
    lcd.setCursor(0, 0);
    lcd.print("!!! WARNING !!!");

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

    tone(BUZZER, 1000);
  }
  else
  {
    lcd.setCursor(0, 0);
    lcd.print("GAS LEVEL:      ");

    lcd.setCursor(0, 1);
    lcd.print("NORMAL          ");

    noTone(BUZZER);
  }

  delay(300);
}