#define MQ2pin A0
#define buzzerPin 8
#define redLedPin 7
#define greenLedPin 4

float sensorValue;  // variable to store sensor value

void setup()
{
  pinMode(buzzerPin, OUTPUT);
  pinMode(greenLedPin, OUTPUT);
  pinMode(redLedPin, OUTPUT);
  Serial.begin(9600); // sets the serial port to 9600
  Serial.println("Gas sensor warming up!");
  delay(5000); // allow the MQ-2 to warm up
}

void alarmOn() {
  tone(buzzerPin, 500, 1000);      // Activate the buzzer
  digitalWrite(redLedPin, HIGH);   // Turn on the red LED
  digitalWrite(greenLedPin, LOW);  // Turn off the green LED
}

void alarmOff() {
  tone(buzzerPin, 0, 0);               // Turn off the buzzer
  digitalWrite(redLedPin, LOW);    // Turn off the red LED
  digitalWrite(greenLedPin, HIGH); // Turn on the green LED
}

void loop()
{
  sensorValue = analogRead(MQ2pin); // read analog input pin A0
  Serial.print("Sensor Value: ");
  Serial.print(sensorValue);
  
  if (sensorValue > 200) {         // Threshold for smoke detection
    alarmOn();
    Serial.print("Smoke detected!");
    Serial.println(" PERINGATAN: Asap terdeteksi!");
  } else {
    alarmOff();
    Serial.print("No Smoke detected");
    Serial.println(" Normal: Tidak ada asap terdeteksi.");
  }

  delay(2000); // wait 2s for next reading
}