BME688 BSEC IAQ need calibration

Hello!

I'm trying to use a BME688 sensor with the BSECv2 lib.

Everything seems to work ok except the IAQ, CO2, BreathVOC, etc. The accuracy is 0 when I start my program, then changes to 1 after ~5 minutes. According to the datasheet, 1 means it needs a calibration. I tried to close the sensor in a box with "bad" air for ~30mins, then take it outside for ~30mins. But the accuracy doesn't want to change. Also keep getting 25 for IAQ and 500 for CO2 equivalent.

What could cause my problem?

Thanks for the help!

Best reply by micha_pr

In normal case the BME680 sensor need a calibration time of some hours - if the environment have changed conditions.
If not - it can take 3 days (in my case for a home office room) until it will reach iaqAccuracy 3.

But after some time it can go back to "1" (not clear why in this time - see /mems-sensors-forum-jrmujtaw/post/bme680-iaq-accuracy-going-from-3-o-1-QoiVD02fRhf9Do3)

In any case you should save the sensor state - there is a sample in code. If not, the sensor will start at new with calibration when restarting the sketch.

Michael

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