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twartzek / bme680-raspberry

C Code which reads measurements of a BME680 connected to a raspberry pi.
MIT License
20 stars 9 forks source link

calibration and gas readings #1

Open And1DS opened 6 years ago

And1DS commented 6 years ago

Hi, first of all thanks for your code, it allowed me to finally get the bme680 working on my Raspi3!

From what I have seen in code of others, they calibrate the sensor somehow prior to get the readings. Is this done in the bme680 driver already or would it be to be added?

I found a C Library from Bosch BSEC which they recommend to use, but i dont think it works on the Raspi3 - i think that library would then also give you some GAS values or Air Quality Index, do you know how to make sense of the gas resistance value?

I just run 100 measurements with 10sec delay and the gas resistance value kept increasing...

Some times I am not getting any value for the temperature, it just stays at 0.00 - and its definitely not that cold in here!! :-)

cheers! Andreas

heinemml commented 6 years ago

Hi, I'd also like to thank @twartzek for this Code. Made it pretty easy to test my sensor and verify it against a python implementation I'm currently putting together.

But I'm also trying to make sense of the Gas Resistance values. I would be more than happy for any explanation what this actually represents.

@AjejeBraso I think you're correct in assuming that the BSEC Lib which can calculate the IAQ Value is not available for the Raspberry... So the Gas measurement is currently pretty useless... bummer...

ludwich66 commented 6 years ago

I have set here times a 12 hours curve of the sensor. http://www.ludwich.de/ludwich/Sensoren-TFLG.html The zag after about an hour seems to hang with the sunset together. The room was in the measuring period without persons, only three small room plants. The windows closed. Who craps the IAQ index ;-)

ludwich

twartzek commented 6 years ago

Hello together,

thanks for your comments. In deed the BSEC library was not used, hence the gas values just show the raw resistance value. This will also change in case of humidity or temperature change. That is why, Bosch developed the BSEC algorithm which is a sensor fusion algorithm to calculate a reliable air quality value.

Someone told me, the sensor needs some days in working to settle. So it would be interesting if the gas values also change after several days at constant conditions.

Best, Tobias

ludwich66 commented 6 years ago

There is another Library on https://github.com/pimoroni/bme680 it is with a implementation for IAQ

??: The Resistance Value is with this Prog <> 80 K Ohms, the Pimorinis library is <>230K Ohms.

Gruss ludwich