#define MQ2_ANA A1
#define MQ2_DIG 2
#define redLed 12
#define buzzer 8
#define dht22 1
void setup() 
{
  Serial.begin(9600);
  pinMode(MQ2_ANA, INPUT);
  pinMode(MQ2_DIG, INPUT);
  pinMode(redLed, OUTPUT);
  pinMode(buzzer, OUTPUT);
}
void loop() 
{
  int smokVal = analogRead(MQ2_ANA);
  delay(1000);
  if(smokVal > 450)
  {
   tone(buzzer, 8);
   delay(500);
   noTone(buzzer);
  }
  else
  {
   noTone(buzzer);
  }
}