Internal calibration for humidity, other parameters

[mayor]

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.

[Minhwan]

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]

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]

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]

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?