getCO2() sends wrong serial command? about mh-z19 HOT 4 CLOSED

Also the reading itself is way off, it starts off at ~8000 and goes down to ~3000 after a minute.

from mh-z19.

It seems that using .getCO2(false); will issue the correct command - not sure why this is not the default behavior.

from mh-z19.

The default is an alternative not documented which allows you to return a CO2 reading uncapped (unlimited by range or background CO2); it's useful to see if the sensor is misbehaving. For example in your case it might be above your defined range - you know there's an issue. You can find these details in the examples (though not in BasicUsage, I've updated this) or in the library it's self which is mostly annotated.

I would guess that your sensor has not been calibrated correctly, which can be awkward. If you're not having any luck with the example, try pulling the zero HD pin low for 7 Sec (see the datasheets in extras) or the Calibration example (which has been updated to be clearer also).

from mh-z19.

Closing due to inactivity - feel free to reopen.

from mh-z19.