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danwahl / adanet-co2-monitor

Adanet CO₂ Monitor
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Verify that the SCD40 works as a drop-in replacement for the SCD41 #8

Closed danwahl closed 1 year ago

danwahl commented 2 years ago

The Low Power Operation document says:

Power Cycled Single Shot Operation (SCD41 only)

But the firmware is not currently using single-shot operation, so I don't think this applies.

Still, worth verifying before purchasing SCD40s in bulk!

danwahl commented 1 year ago

I verified this, but still purchased the SCD41 for the first build round (since it was in stock). Given the functionality currently being used, I don't think it matters which of the SCD4x sensors is used. Keeping this open as a reminder to adjust the README accordingly.

danwahl commented 1 year ago

I confirmed that the SCD40 works using the periodic measurement mode, same as the SCD41 (which is expected).

I then tried to use the "Power Cycled Single Shot Operation" as described in the above document (which required modifying the arduino-i2c-scd4x library) but was getting suspicious temperature/humidity readings.

I'm not 100% sure that using the sensor in periodic measurement mode for two samples is a valid way to do low-power operation, and so I updated the README to recommend the SCD41 for now (so that a firmware fix could in theory resolve any issues).