BME680 and VOC gas readings

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Tom_Henry
 
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BME680 and VOC gas readings

Post by Tom_Henry »

BME680 VOC gas sensor

I have set up the BME680 and the PCF8523 with the Metro 4 AirLift Lite that sends RTC and BME680 readings to an Adafruit Dashboard.

See attached copy of the code.py and of the dashboard.

I am trying to make sense out of the VOC gas reading. I just get a very larger number and have no idea how to figure out what this number means.

I read this on an Adafruit page:

“Gas is returned as a resistance value in ohms. This value takes up to 30 minutes to stabilize! Once it stabilizes, you can use that as your baseline reading. Higher concentrations of VOC will make the resistance lower.”

Can you tell what different values of the VOC gas reading mean? Or perhaps you can direct me to a url that helps me understand what the reading means.

Thank you,

Tom Henry
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Metro BME680.png
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code.py
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mikeysklar
 
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Re: BME680 and VOC gas readings

Post by mikeysklar »

There is a good discussion here with some simple formulas to convert the resistance in ohms gas readings to AQI.

https://forums.pimoroni.com/t/bme680-ob ... gs/6608/17

Code: Select all

comp_gas = log(R_gas[ohm]) + 0.04 log(Ohm)/%rh * hum[%rh]

Code: Select all

comp_gas = log(gas_reading) + 0.04 * humidity_reading

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