MQ-135 Gas Sensor
Resistive MQ-135 sensor for detecting ammonia, benzene, alcohol, CO2, and other harmful gases; outputs an analog voltage proportional to gas concentration.
Pinout
- DOUT1
digital threshold output
Type · GPIO - AOUT2
analog output
Type · Analog - GND3
ground
Type · Ground - VCC4
supply
Type · Power
| Pin | Position | Type | Function |
|---|---|---|---|
| DOUT | 1 | GPIO | digital threshold output |
| AOUT | 2 | Analog | analog output |
| GND | 3 | Ground | ground |
| VCC | 4 | Power | supply |
Pin details
4 connections- DOUT1
digital threshold output
GPIO - AOUT2
analog output
Analog - GND3
ground
Ground - VCC4
supply
Power
Start wiring
I2C · Analog · UART · 3.3 – 5 V · Breakout
Waveshare lists MQ-2 for combustible gases and smoke, MQ-3 for alcohol, and MQ-135 for mixed indoor pollutants such as NH3, NOx, alcohol,…
Module pins: VCC, GND, DOUT, AOUT. Schematik maps them to your board in the app.
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