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Sensirion / arduino-i2c-scd4x

Arduino library for Sensirion SCD4x sensors
BSD 3-Clause "New" or "Revised" License
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Undocumented sleep mode and powerDown() / wakeUp() command codes #7

Closed dominik-ho closed 2 years ago

dominik-ho commented 2 years ago

Hello dear all,

in the library, there are the powerDown() and wakeUp() functions, which send the command codes 0x36E0 and 0x36F6 respectively. Also, the "sleep mode" is mentioned in the comments of these functions in SensirionI2CScd4x.h https://github.com/Sensirion/arduino-i2c-scd4x/blob/59aaa4d9ce9eae00865f398c31e2a38f0832d81e/src/SensirionI2CScd4x.h#L380.

My problem is that neither these commands, nor their codes nor the sleep mode are mentioned at all in the latest SCD4x datasheet (Version 1.1). I've attached the Datasheet's Command Overview: image

As you can see, they are missing.

My question is whether these commands work as described in the comments or if there's a reason they are not included in the Datasheet and whether it's safe to use these two functions.

Thanks in advance.

MBjoern commented 2 years ago

Dear @DominikHoen

Powering down the sensor between single shots will likely result in increased signal noise and might compromise sensor accuracy. Also, power-cycling the sensor is not compatible with the automatic self-calibration algorithm that ensures highest long-term stability.

I hope this helps to answer your questions.

Best regards