Robert Gillespie asked 4 years ago
I’m running two BME680s side by side from two different UNOs. The temperature, pressure, and humidity readings are comparatively within range. The Gas, however, is very different. The readings for the Gas are stable. They are at this moment 434.70 and 1064.93. I’m displaying them on two oleds. Is there something wrong with one of the sensors or both? How do you convert to a relative IAQ? Could I use a cleaner of some sort to wipe the exposed section of the BME680.
Sara Santos Staff answered 4 years ago
Hi Robert.
The gas readings vary with many factors and they may need to be calibrated. But, I’m not familiar with that process.
There is a library for the BME680 sensor provided by bosch to get IAQ from the gas resistance and other factors.
We have already a discussion opened about that issue here on the forum: https://rntlab.com/question/bme680-and-iaq-index-on-datasheet/
It seems there is some issue wi
th the library and the ESP32.
I haven’t experimented it with the Arduino. Maybe it is working with the Arduino: https://github.com/BoschSensortec/BSEC-Arduino-library
To clear a section of the OLED display, it may be useful taking a look at this discussion: https://forum.arduino.cc/index.php?topic=383909.0
I hope this helps.
Regards,
Sara
Robert Gillespie answered 4 years ago
Hi Sara:
I’m following the discussion on the BME680 and IAQ index that you are having with William Lucid. It is very interesting. My question was why do two bme680s have two widely different gas readings when setting side by side? My 2nd question suggests that maybe there is contamination of the metal sensor on one or both of the bme680s that could account for the wide differences in gas readings and if the metal sensor could be cleaned a bit with something to remove contamination.
My OLED displays work great.
Have a great day Sara and stay safe.
Bob
Sara Santos Staff answered 4 years ago
Hi.
Yes, your assumption might be correct. Also, note that the temperature and humidity can influence the gas resistance readings.
Regards,
Sara
William Lucid answered 4 years ago
Hi Robert,
I believe it takes a period of 20 -30 minutes for the BME680 to stablize into “normal” operation. Have read refernce to starting the BME680 in “clean” air. Just, not sure how to achive “clean” air.
Before beginning; should be noted, “BSEC” library does not run on the “Arduino Uno” due to memory requirements.
Do you have the BSEC library installed and functional?
Next, you need to run “Bosch,” BSEC Library’s “basic_config_state.ino?”
BSEC Library’s, “basic_config_state.ino” Running the sketch can take much time; comment in sketch, “every 360 minutes writes to EPROM, 4 times a day” Repeat for second BME680.
Challenge:
After running “basic_config_state.ino” try placing one BME680 over a jar contain a small amount of isopropyl alcohol. Run the “BSEC, basic.ino” example; so the EPROM does not get updated. Record results.
Repeat process for second BME680. Are your results closer to being the same now?
William