MQ2

int mq2Pin = A1;
int dig = 13;

void setup() {
  // put your setup code here, to run once:
  pinMode(mq2Pin, INPUT);
  pinMode(13, INPUT);
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  int analVal = analogRead(mq2Pin);
  int digiVal = digitalRead(dig);

  Serial.print("Analog Value = ");
  Serial.print(analVal);
  Serial.print("    Digital Value = ");
  Serial.println(digiVal);
  delay(500);
}