const int sensorPin = A0;   // Pin connected to MQ sensor AO
const int buzzerPin = 8;    // Pin connected to Buzzer (optional)
const int ledPin = 13;      // Built-in LED on Arduino

// Threshold for detection (0 to 1023)
// Adjust this value based on your room's clean-air reading
const int gasThreshold = 400; 

void setup() {
  pinMode(sensorPin, INPUT);
  pinMode(buzzerPin, OUTPUT);
  pinMode(ledPin, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  int gasValue = analogRead(sensorPin); // analogRead returns an integer (0–1023)
  
  Serial.print("Gas Sensor Value: ");
  Serial.println(gasValue);

  // Check if gas level exceeds the threshold
  if (gasValue > gasThreshold) {
    digitalWrite(ledPin, HIGH);        // Turn on LED alert
    digitalWrite(buzzerPin, HIGH);     // Sound buzzer
    Serial.println("WARNING: Gas Detected!");
  } else {
    digitalWrite(ledPin, LOW);         // Turn off LED
    digitalWrite(buzzerPin, LOW);      // Turn off buzzer
  }

  delay(500); // Small delay to prevent spamming the serial monitor
}