SensorTile temperature readings

David Heise · ‎2018-07-07

Posted on July 07, 2018 at 14:09

I am attempting to use a SensorTile for continuous audio recording and environmental monitoring, recording data to the SD card hosted in the cradle. I am finding that temperature readings are unreliable/unusable, which I hypothesize is due to local heat being generated by the SensorTile. I believe the temperature sensor on the cradle is the HTS221.

During recording, temperature readings start at ambient temperature (as recorded by an external reference) and begin to rise, typically to 31-33 C.

Does this hypothesis seem reasonable? Has anyone else encountered this issue? Is the heat likely generated by the STM32L476 MCU? Is there a recommended heat sink to mitigate this issue? Other known/recommended solution?

Thanks in advance.

Davide G · ‎2018-09-17

Hi David,

Unfortunately, measuring the ambient temperature on a pcb is a delicate matter.

Even if we took some precautions during the design of the board (see AN4722 https://www.st.com/resource/en/application_note/dm00208002.pdf), in such a small platform it is very difficult to isolate the sensor from the other heat sources on the board (I believe the SD card in your case).

It's maybe possible to reduce the heat coming from the STM32 implementing some low power optimization in the code; see FP-SNS-ALLMEMS2 function pack as an example:

https://www.st.com/en/embedded-software/fp-sns-allmems2.html