MQ2 Gas sensor is a Metal Oxide Semiconductor (MOS) type Gas Sensor mainly used to detect gases like Methane, Butane, LPG, Smoke, etc. It is also known as Chemiresistors as the gas detection is based on the change of resistance of the sensing material when the Gas comes in to contact. If you want to measure a different type of Gas you can check these Gas Sensors. 

MQ2 Gas sensor module works on 5V DC and uses around 800mW. It can detect LPG, Smoke, Alcohol, Propane, Hydrogen, Methane and Carbon Monoxide concentrations in a range of 200 to 10000 ppm.

Specifications:

• Operating Voltage is +5V
• Analog output voltage: 0V to 5V
• Digital Output Voltage: 0V or 5V (TTL Logic)
• Preheat duration 20 seconds
• Can be used as a Digital or analog sensor
• The Sensitivity of Digital pin can be varied using the potentiometer

How to interface with an Arduino?

The MQ-2 gas sensor module is a versatile sensor used to detect a variety of gases, including methane, butane, LPG, and smoke. It is commonly used in applications such as gas leak detection and air quality monitoring. This guide will walk you through the process of interfacing the MQ-2 sensor with an Arduino to measure gas concentrations.

Components Required

• Arduino Uno

• MQ-2 Methane Butane LPG Smoke Gas Sensor Module

• Jumper wires

• Breadboard

• LED (optional for visual feedback)

• Resistor (220 ohms, optional for LED)

Understanding the MQ-2 Gas Sensor Module

The MQ-2 sensor module detects gases using a heating element and a gas-sensitive layer. It has the following pins:

1. VCC: Power supply (5V)

2. GND: Ground connection

3. AO: Analog output pin, which provides a voltage proportional to the gas concentration

4. DO: Digital output pin, which provides a HIGH or LOW signal based on a set threshold

Connecting the MQ-2 to Arduino

Follow these steps to connect the MQ-2 sensor to your Arduino:

1. Connect the VCC pin of the MQ-2 to the 5V pin of the Arduino.
2. Connect the GND pin of the sensor to the GND pin of the Arduino.
3. Connect the AO pin of the sensor to the A0 analog input pin on the Arduino.
4. (Optional) Connect the DO pin to a digital pin (e.g., D2) if you want to use the digital output.

Optionally, you can also connect an LED to pin 13 of the Arduino with a 220-ohm resistor for visual feedback.

Arduino Code

Below is the Arduino code to read the analog output from the MQ-2 sensor. This code will read the sensor values and print them to the Serial Monitor.

#define MQ2AnalogPin A0 // MQ-2 sensor analog output connected to A0

void setup() {
  pinMode(MQ2AnalogPin, INPUT); // Set the MQ-2 pin as input
  Serial.begin(9600); // Begin serial communication for debugging
}

void loop() {
  int sensorValue = analogRead(MQ2AnalogPin); // Read the analog value from the sensor
  Serial.print("MQ-2 Sensor Value: ");
  Serial.println(sensorValue); // Print the sensor value to the Serial Monitor
  delay(1000); // Delay for 1 second
}

Conclusion

By following this guide, you have successfully interfaced the MQ-2 gas sensor with an Arduino Uno. This setup allows you to monitor gas concentrations in real time. You can use the analog output to gauge gas levels and the digital output for threshold-based detection. For more advanced applications, you may need to calibrate the sensor and implement more complex algorithms to interpret the sensor data accurately.