What is MQ-7 Gas Sensor?

The MQ-7 is a gas sensor capable of detecting carbon monoxide (CO) gas concentrations. It is widely used in air quality monitoring and safety systems.

Working Principle of MQ-7

The MQ-7 sensor detects CO by heating the sensing material and measuring the change in resistance as the gas reacts with it. The output is an analog signal proportional to the CO concentration.

• The sensor heats the sensing material inside.
• The resistance of the sensor changes based on the CO concentration.
• ESP32 reads the analog signal and processes the data.

Formula: CO Concentration = Resistance Measurement

Components Required

• ESP32 board
• MQ-7 Gas Sensor
• Jumper wires
• Breadboard

Pin Configuration of MQ-7

• VCC: Connects to 5V on ESP32
• GND: Connects to GND on ESP32
• AOUT (Analog Out): Sends analog signal to ESP32

Make sure to calibrate the sensor to achieve accurate readings.

Wiring MQ-7 Gas Sensor to ESP32

• VCC -> 5V
• GND -> GND
• AOUT -> GPIO 34

Arduino Code for ESP32 + MQ-7

1int mq7Pin = 34;
2void setup() {
3  Serial.begin(115200);
4}
5void loop() {
6  int sensorValue = analogRead(mq7Pin);
7  Serial.print("CO Concentration: ");
8  Serial.println(sensorValue);
9  delay(1000);
10}

Code Explanation (Line-by-Line)

• int mq7Pin = 34;: Defines GPIO 34 for reading analog data from the MQ-7.
• int sensorValue = analogRead(mq7Pin);: Reads the analog data from the sensor.

Applications

• Air quality monitoring
• Carbon monoxide detectors
• Home safety alarms

Conclusion

The MQ-7 gas sensor provides an easy and effective way to detect carbon monoxide gas, and with ESP32, it is suitable for various air quality monitoring and safety applications.