9532 – MQ-7 Gas Sensor/en

Documentation notice: This technical documentation was independently rewritten from an archived supplier source. Check technical details and commands against the product version and manufacturer documentation before use.

Summary

The MQ-7 is a carbon monoxide sensor based on tin dioxide (SnO2). Its conductivity increases as CO concentration rises. The module provides analog and digital outputs, operates at 2.5–5.0 V, and requires about one minute of preheat time to heat the sensitive material.

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Technical overview

Sensitivity: specialized for carbon monoxide; output voltage rises with gas concentration.
Operating voltage: 2.5 V to 5.0 V at VCC; ground at GND.
Dimensions: 40.0 mm × 21.0 mm; mounting hole diameter 2.0 mm.
Analog output AOUT and digital output DOUT are available on the module.
Preheat time: about 1 minute so the sensitive material reaches operating temperature.
Indicator LED: lights up when the target gas is present; turns off when the sensor is removed.
Pico wiring: VCC→3.3 V, GND→GND, AOUT→GP26, DOUT→GP22.
STM32F103RB wiring: VCC→3.3 V, GND→GND, AOUT→PA6, DOUT→PA4.
Arduino UNO wiring: VCC→5 V, GND→GND, AOUT→A0, DOUT→D2.
Examples are provided for Pico (C/C++ and MicroPython), STM32 (HAL library), and Arduino.

Commands and examples – verify before use:

sudo apt-get install p7zip-full
cd ~
sudo wget https://files.waveshare.com/upload/4/48/MQ-7-Gas-Sensor-code.7z
7z x MQ-7-Gas-Sensor-code.7z -o./MQ-7-Gas-Sensor-code
cd ~/MQ-7-Gas-Sensor-code/Pico/c/build/
cmake ..
make -j9
cp main.uf2 /media/pi/RPI-RP2/

Notes and version constraints

The example environments are based on STM32F103RBT6/H743 and Arduino UNO; other boards require custom adaptations.
The sensor must be preheated for about one minute before reliable readings; without this warm-up, values are unreliable.
The Pico firmware choice (e.g., rp2-pico-20210418-v1.15.uf2) is version-sensitive – verify that the current firmware matches your board before flashing.
The download URL in the source points to an external archive; its validity should be verified before use.
No calibration, certification, or warranty information is present in the source material – please confirm with the supplier.

Source and revision record

MQ-7 Gas Sensor - Waveshare Wiki
Source revision: 75812
Captured: 2026-08-29T09:43:46+00:00
SHA-256: 0d145d12c9990357fe8780633e95781431d81fa3abc13a88bef70cba32f8d9f6