Air quality sensor for CO2, ammonia, benzene, alcohol. Analog and digital output.
| Pin | Name | Function | Type |
|---|---|---|---|
| VCC | VCC | 5V power | PWR |
| GND | GND | Ground | GND |
| DOUT | DOUT | Digital output, HIGH = pollutant detected | I/O |
| AOUT | AOUT | Analog output, higher = worse air | ADC |
The MQ-135 air quality sensor detects ammonia, benzene, alcohol, CO2, and other harmful gases. It is commonly used in air quality monitoring systems and ventilation control. Outputs both analog and digital signals.