How to Use MQ2: Examples, Pinouts, and Specs

The MQ2 is a versatile gas sensor module capable of detecting a wide range of gases, including carbon monoxide (CO), alcohol, methane (CH4), hydrogen (H2), and smoke particles. This sensor is widely used in the field of safety and air quality monitoring, making it an essential component for environmental sensors, home safety devices, and industrial leakage detection.

• Indoor Air Quality Monitoring: To detect harmful gases and ensure a healthy living environment.
• Industrial Safety: To monitor gas concentrations and prevent hazardous situations in factories.
• Home Safety Devices: Integrated into smoke alarms and carbon monoxide detectors.
• DIY Projects: Used by hobbyists for creating custom gas detection systems, often interfaced with microcontrollers like Arduino.

• Sensor Type: Semiconductor
• Detection Gases: LPG, Propane, Methane, Alcohol, Hydrogen, Smoke
• Concentration Range: 200 to 10000 ppm (parts per million)
• Preheat Duration: 20 seconds
• Supply Voltage: 5V DC
• Output Voltage: 0.1-0.3V (relative to gas concentration)
• Operating Temperature: -10 to 50°C
• Load Resistance: Adjustable via onboard potentiometer

1. Power Connection: Connect the VCC pin to a 5V supply and the GND pin to the ground.
2. Analog Output: Connect the AOUT pin to an analog input on your microcontroller to read gas concentration levels.
3. Digital Output: Connect the DOUT pin to a digital input on your microcontroller if you want to use a predefined threshold value for gas detection.

• Calibration: The MQ2 sensor requires calibration to accurately measure gas concentrations. This can be done by exposing the sensor to a known gas concentration and adjusting the onboard potentiometer until the desired output is achieved.
• Warm-Up Time: Allow the sensor to preheat for at least 20 seconds to stabilize its readings.
• Ventilation: Ensure proper ventilation around the sensor to prevent saturation and to allow for accurate readings.
• Avoid Extreme Conditions: Keep the sensor away from extreme temperatures and humidity levels to prevent damage and inaccurate readings.

// MQ2 Gas Sensor Example Code for Arduino UNO

int analogPin = A0; // Analog input pin connected to AOUT on the MQ2
int digitalPin = 2; // Digital input pin connected to DOUT on the MQ2
int sensorValue = 0; // Variable to store the sensor value

void setup() {
  pinMode(digitalPin, INPUT); // Set the digital pin as input
  Serial.begin(9600); // Start serial communication at 9600 baud rate
}

void loop() {
  sensorValue = analogRead(analogPin); // Read the analog value from sensor
  Serial.print("Gas concentration (analog): ");
  Serial.println(sensorValue); // Print the analog reading

  if (digitalRead(digitalPin) == HIGH) {
    // Check if the digital output is HIGH
    Serial.println("Gas detected!");
  } else {
    Serial.println("No gas detected.");
  }
  delay(1000); // Wait for 1 second before the next loop
}

• Inconsistent Readings: If the sensor provides inconsistent readings, ensure that it has been properly calibrated and that there is adequate ventilation.
• No Response to Gas: Check the power supply and wiring connections if the sensor does not respond to gas exposure.
• Sensor Not Heating Up: If the sensor does not heat up, verify the supply voltage and connections to the VCC and GND pins.

• Calibration: Perform calibration in a well-ventilated area with a known gas concentration.
• Sensor Replacement: The MQ2 sensor has a limited lifespan. If the sensor fails to operate after troubleshooting, consider replacing it.
• Check Connections: Loose or incorrect wiring can cause issues. Double-check all connections.

Q: How long does the MQ2 sensor last? A: The lifespan of the MQ2 sensor is typically around 2-5 years, depending on usage and environmental conditions.

Q: Can the MQ2 sensor detect natural gas? A: Yes, the MQ2 sensor can detect methane (CH4), which is the primary component of natural gas.

Q: Is the MQ2 sensor sensitive to alcohol? A: Yes, the MQ2 sensor can detect alcohol vapors, making it suitable for breathalyzers and similar applications.

Q: What is the best way to test the MQ2 sensor? A: The best way to test the sensor is by using a known gas concentration and observing the sensor's response while adjusting the onboard potentiometer for calibration.