BME680 calibration parameters are constant?

[timmbo]

Dear all,

I'm using the BME680 together with a MCU which only has 16kByte of Flash memory. I'm using the BME680 driver provided by Bosch, but the driver alone eats up quite a lot of memory. Especially the calc_* routines are memory hungry. Honestly, I don't fully understand why the BME680 can't do these calculations internally.

Anyhow, I would like to only store the raw adc value and later, by post processing, calculate temperature, humidity, ... from it. For the post processing I would then need the raw data plus the device-specific calibration data (par_h1, par_h2, .... and so on).

Question is (couldn't find it in the documentation): is the calibration data in the calibration registers (par_*) constant for every single BME680 (once written during production) or does it change over time due to internal calibrations?

I briefly tested it and they seem constant, I would just like to confirm it.

Thanks in advance,

Timm

[handytech · Accepted solution]

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@timmbo wrote:

Question is (couldn't find it in the documentation): is the calibration data in the calibration registers (par_*) constant for every single BME680 (once written during production) or does it change over time due to internal calibrations?

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Calibration registers are one time programmable (OTP) set during production, thus are constant and will not change over time. As long as you can keep track of which calibration registers belong to which specific sensor/device, running the compensation formulas in post-processing sounds possible.