Interfacing MQ-6 Gas Sensor with Arduino

Have you ever been curious about how devices detect gas leaks? With the MQ-6 gas sensor, you can create your very own gas detection system! This amazing sensor can identify gases like LPG, butane, and propane—common fuels used in cooking and heating. Let’s dive into an exciting and simple project to learn how to use the MQ-6 with an Arduino.

How the MQ-6 Sensor Works

The MQ-6 sensor has a tiny part inside called a sensing element. When there’s gas in the air, this part reacts with it, causing the sensor to send a signal to the Arduino. The more gas in the air, the stronger the signal.

The sensor has two types of outputs:

1. Analog Output (AO): Shows the amount of gas in the air.

2. Digital Output (DO): Tells if the gas level is above a set limit (like a simple ON/OFF switch).

Specifications

Sensor pinout:

Hardware Requirements

1x Arduino
1 x Buzzer
1x MQ-6 Gas Sensor
1x breadboard
Some jumper wire
A Small Lighter (for testing, under adult supervision)

Circuit Diagram

Interfacing MQ-6 Gas Sensor with Arduino

MQ-6 Sensor Configuration

Buzzer Configuration

Code

const int analogPin = A0; // Connect AO to A0
const int digitalPin = 2; // Connect DO to D2
const int alertPin = 3;   // Buzzer or LED (optional)

void setup() {
  Serial.begin(9600); // Start serial communication
  pinMode(digitalPin, INPUT);
  pinMode(alertPin, OUTPUT);
}

void loop() {
  int gasLevel = analogRead(analogPin); // Read gas level from Analog Pin
  Serial.print("Gas Level: ");
  Serial.println(gasLevel);

  int threshold = digitalRead(digitalPin); // Check threshold from digital Pin
  if (threshold == HIGH) {
    Serial.println("Gas level is too high!");
    digitalWrite(alertPin, HIGH); // Turn on buzzer or LED
  } else {
    digitalWrite(alertPin, LOW); // Turn off buzzer or LED
  }

  delay(100); // Wait 100 millisecond
}

1. Variables Declaration

const int analogPin = A0; // Connect AO to A0
const int digitalPin = 2; // Connect DO to D2
const int alertPin = 3;   // Buzzer or LED (optional)

I) analogPin: Reads the gas level as an analog signal, providing a range of values.
II) digitalPin: Reads a digital signal (HIGH/LOW) to indicate whether the gas level exceeds a preset threshold.
III) alertPin: Controls a buzzer or LED to signal if the gas level is too high

2. Setup Function

void setup() {
  Serial.begin(9600); // Start serial communication
  pinMode(digitalPin, INPUT);
  pinMode(alertPin, OUTPUT);
}

 I) Serial.begin(9600): Starts communication with the computer so data can be sent to the Serial Monitor.
II) pinMode(digitalPin, INPUT):Configures the digital pin to read the sensor’s threshold output.
III) pinMode(alertPin, OUTPUT):Prepares the alert pin to control a buzzer or LED.

3. Main Loop

void loop() {
  int gasLevel = analogRead(analogPin); // Read gas level from Analog Pin
  Serial.print("Gas Level: ");
  Serial.println(gasLevel);

I) analogRead(analogPin): Reads the gas concentration as a numerical value from the sensor’s analog output. The value typically ranges from 0 to 1023.
II) The gas level is displayed on the Serial Monitor for real-time monitoring.

  int threshold = digitalRead(digitalPin); // Check threshold from digital Pin
  if (threshold == HIGH) {
    Serial.println("Gas level is too high!");
    digitalWrite(alertPin, HIGH); // Turn on buzzer or LED
  } else {
    digitalWrite(alertPin, LOW); // Turn off buzzer or LED
  }

  delay(100); // Wait 100 millisecond
}

I) digitalRead(digitalPin): Reads the digital pin to check if the gas level exceeds the sensor’s preset threshold.
II) if (threshold == HIGH): If the sensor’s digital output is HIGH, it indicates the gas level is too high:

a) A warning message is sent to the Serial Monitor.
b) The buzzer or LED connected to the alert pin is activated (turned on).

III) else: If the gas level is below the threshold:
IV) The alert signal (buzzer/LED) is turned off.
V) delay(100): Introduces a short pause (100 milliseconds) before repeating the loop. 

How It Works

1. The analog output (AO) provides a continuous reading of gas concentration, which you can monitor via analogRead().
2.The digital output (DO) indicates whether the gas concentration exceeds a preset threshold. This threshold can be adjusted using the onboard potentiometer.
3.The code includes an optional buzzer or LED to provide alerts.

Calibration

1. Connect the sensor and let it warm up for 2–5 minutes.
2. Adjust the potentiometer on the sensor module to set the desired threshold.

Serial Terminal:

Serial Plotter: