BME680: Recommendations for gas sensing heating temperature and time?

[gbeloev]

Hi everyone,

I implemented code to read T/P/H and gas resistance including basic compensation based on the Bosch reference code. To measure gas resistance, we have to set specific temperature and heating time. My question is: what are the recommended values and how do they affect the results?

• What are the pros and cons of using higher/lower temperature and longer/shorter time?
• Does the gas sensor react to VOCs faster/slower with different temperature/time settings?
  • Does it recover faster/slower when exposed to clean air?
• Do certain VOCs absorbed (and hence measured) better/worse with different temperature settings?
• Do I need to sweep temperature settings, e.g, make several measurements between 200C and 400C to get a more comprehensive result?
• Do I need to use a certain setting intermittently, e.g., every 100 measurements at 300C do one at 400C?

To clarify, I know about the BSEC library, and I already tried using it in my project. But I also want to understand how to make basic gas resistance measurements in case I don't need the features provided by the library.

Thanks!

[BSTRobin]

Hello gbeloev,

At present, we provide BSEC algorithm library and do not disclose how it is implemented.
You could develop your own products based on BSEC.

[gbeloev]

Thanks. I am not asking about IAQ, eCO2, or any other calculated values, the calculation of which is apparently proprietary. All I am asking about is gas resistance measurement. This is documented in the data sheet and exposed in the open-source API, what's missing is just some recommendations on usage. Are these proprietary as well?

Regards,
-- Georgi

[BSTRobin]

Hello gbeloev,

Currently, gas registance as raw values are transformed to an index for air quality(IAQ) by smart algorithm inside BSEC. There are no other usage examples.