Hallo,

gibt es eine Möglichkeit die automatische Kalibrierfunktion (ASC) des Sensirion SCD30 CO2 Sensors zu deaktivieren? Wir nutzen 12 dieser Sensoren für bauphysikalische Experimente und würden ASC gerne deaktivieren, aber finde dazu nichts in der API Beschreibung.

Danke im voraus...Gabriel

Edited August 24, 2022 at 05:27 PMAug 24, 2022 by gabrojas

Cross reference: CO2 Bricklet 2.0 accuracy

Thanks! That helps already a lot, I had read it before, but after reading it again I still don't know if I can switch it off via API or if I have to change sensor firmware. A short answer on that would be highly appreciated, then I would know if feasible for me or if I need to involve collegues...Thanks

Hi Gabrojas,

It is not possible to switch ASC on/off via API with the current firmware.

That other thread ultimately led to firmware 2.0.3, which forces ASC on at startup. Before that, at least some CO2 Bricklets erroneously shipped with ASC switched off.

I would welcome the option to control ASC manually, but if you know how to build firmware, it might be feasible to implement yourself. This is the diff for the above FW change.

Hope this helps.

Thanks Superp,

Do you know: does that mean that if I install firmware 2.0.2 the ASC will be turned off? The changelog for 2.0.3 says "Make sure ASC is enabled on each startup", but does that mean that ASC is disabled with 2.0.2 after a startup or not necessarily and if ASC is activated (now with 2.0.3) it stays activated, even if you flash with 2.0.2?

I don't know.

Did you read the thread I linked to above?

Firmware < 2.0.3 did not touch ASC, it was assumed to be activated during manufacturing.

But, apparently, at least some Bricklets were shipped with ASC not activated. So, I would say, a Bricklet that has never run 2.0.3 has ASC in an unknown state.

2.0.3. activates ASC.

2.0.2. and older do not touch ASC.

So the question is: does the Bricklet retain the state of ASC between restarts?

Thanks! Yes, I read the thread and I read the GitHub documentation (and the available changelog. But it wasn't conclusive for me how some sensors with old firmware, where shipped with and some without ASC turned off. But thanks to your clarification I get it now. But what you say points to the conclusion that the bricklet remains the state of ASC between restarts...Seems like there is no way around reprogramming the firmware. Thanks again!

I think you're right – once a Bricklet has booted 2.0.3, ASC is on forever – but I am not sure. Would be nice if e.g. @borg could confirm.

vor 12 Stunden schrieb Superp:

I think you're right – once a Bricklet has booted 2.0.3, ASC is on forever – but I am not sure. Would be nice if e.g. @borg could confirm.

You are correct. The SCD30 documentation states:

Zitat

ASC status is saved in non-volatile memory. When the sensor is powered down while ASC is activated SCD30 will continue with
automatic self-calibration after repowering without sending the command.