WeatherDuino Forum

Hi,
Back from holidays and building my new AQM; l notice on the pcb a connector labeled “cal”, could you please explain the use of this connector.
Is there a schematic available?
Regards
Jim

Hello Jim,

The connector labelled "cal" is connected to HD pin on the MH-Z19B sensor, used for a manual ZERO point calibration. Usually doing a ZERO point calibration isn't necessary.
For more info refer to MH-Z19B datasheet:

https://www.winsen-sensor.com/d/files/in...ver1_0.pdf