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    BME688 Development board (Adafruit + 8xBME688) - Temperature sensor - offset of 5 degrees+

    BME688 Development board (Adafruit + 8xBME688) - Temperature sensor - offset of 5 degrees+

    fpineau
    Member

    Hello, 

    On my project, we would to use the BME688 4 in 1 sensor. I already test the COV, humidity and pressuee part.
    And now I work on the temperature sensor BME688. So, I'm posting here because I want to have more information about the data of this temperature sensor.
    I see that in the datasheet the accuracy of this sensor is +/-0.5°C between 0-65°C.

    So for my tests, I did some run with the development board ( Adafruit + 8 BME688) and I put the board in a fidge at 15°C (with a variation of 0.3°C).
    You can see below a 4 days run with the heater profile HP-322 / RDC-3-12. 

    fpineau_2-1663689134221.png

    We can see that we have an offset of 5°C. We are far that the accuracy of  +/-0.5°C between 0-65°C.
    Also I see that this offset change with the heater profile.

    So my questions are : Where come from the offset of 5°C ? And I how I can fix it ?

    Thank you for your precision.

    Florian

    6 REPLIES 6

    BSTRobin
    Community Moderator
    Community Moderator

    Hi fpineau,

    Sorry for the delay reply.
    For your test environment "I put the board in a fidge at 15°C (with a variation of 0.3°C).", can your test environment ensure accurate temperature control at about 15 °?

    BSTRobin
    Community Moderator
    Community Moderator

    Hi fpineau,

    Could you give feedback?

    Hello,

    Sorry for the late feedback. 
    So for this test I used the "ST 1 P SMART PRO" for m POL-EKO APARATURA.
    We have a quality control certificate dated of 04.02.2022.

    And the accurence at every temperature is 0.1°C. (please see an excerpt of the incubator datasheet ).

    fpineau_0-1666684514769.png
    So that's why I don't understand the 5 degree offset

    Best regards.
    Mister Pineau Florian

     

    BSTRobin
    Community Moderator
    Community Moderator

    Hi fpineau,

    If you want to fix it, you can modify the offset which located in function 'ProcessData()' of Bsec2.cpp as following:

    screenshot-1.png

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