MQ7 Gas Sensor Waveshare

With the help of placed on the reverse side of the board, potentiometer, set is the threshold, exceeding of which, causes the output D0 changing from a high to a low status. The pin D0 can be linked directly with a microcontroller or commissioning set, including Arduino, or for example, a module with a buzzer, which will signal a too low or too high level of unwanted gases in the air

Analog output A0

The sensor has an analog output A0, which must be connected to the pin of the converter A/D (analog input in Arduino). This will allow you to measure the proportional voltage signal and more accurately determine the concentration.