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    Internal calibration for humidity, other parameters

    Internal calibration for humidity, other parameters

    mayor
    Established Member

    I have three BME680 sensors whose readings you can see below. They are in the same location, so I would expect readings to be within specified tolerances.

    You can see that the "yellow" sensor is off, especially with regards to humidity.

    I have not seen APIs to apply humidity calibration. Can this be done within the sensor, so that IAQ readings take it into account, and not as a post-reading calculation?

    Note the gas readings are also very different. 

    This isn't confidence-inspiring, but I am willing to try whatever is suggested here.

    Screen Shot 2022-01-21 at 6.37.31 AM.png

    5 REPLIES 5

    Minhwan
    Community Moderator
    Community Moderator

    Hello mayor, 

     

    Which API or BSEC are you using it? 

    We calibrate humidity using calc_humidity fucntion. 

    It should be located in bme680.c or bmx680.c. 

    Thanks, 

    mayor
    Established Member

    Hi Minhwan,

    I had seen that function which takes into account factory "dev->calib.par_h*" parameters. There is no API or documentation (besides reverse-engineering the code in that function) to adjust those params. I'm not even sure they are writable?

    But even then, I use BSEC...

    Minhwan
    Community Moderator
    Community Moderator

    Hello Mayor, 

     

    I'm confused. So please let me clear. 

    The files I mentioned (bme68x.c and bme680.c) are used in BSEC. 

    You can find in our library folder. For example bsec2 case, 

    \bsec_2-0-6-1_generic_release_04302021\BSEC_2.0.6.1_Generic_Release_04302021\examples\bsec2\src\bme68x\bme68x.c

    Please let me know if you have any questions. 

    Thank you. 

    mayor
    Established Member

    Interesting, I am on 1.4.8 and can't find a download on the Bosch site for V2.

    In any event, is there now documentation for the calibration registers? Are they writable? 

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