BSEC_INPUT_HEATSOURCE - How to define?

[rindler]

I have finally created some enclosures for a few of my BME680-sensors. There're quite some holes in it, but still the temperature is 4.6 degrees above the air around. Understand that this is possible to compensate by changing the BSEC_INPUT_HEATSOURCE in some way, but I don't get how I define it? Could you please help me? Am using the basic ino.

Kind regards

[handytech]

The value of BSEC_INPUT_HEATSOURCE will subtracted from BSEC_INPUT_TEMPERATURE to compute BSEC_OUTPUT_SENSOR_HEAT_COMPENSATED_TEMPERATURE.

BSEC_OUTPUT_SENSOR_HEAT_COMPENSATED_HUMIDITY also takes into account BSEC_INPUT_HEATSOURCE to convert BSEC_INPUT_HUMIDITY from temperature BSEC_INPUT_TEMPERATURE to BSEC_OUTPUT_SENSOR_HEAT_COMPENSATED_TEMPERATURE.

[rindler]

Thanks for your reply!
Yes, but I don't quite understand how I define the value in my arduino sketch. Obviously it is not by using #define BSEC_INPUT_HEATSOURCE 4.6; or similar, hehe. Or do I define it somehow in the iaq.begin section?

[o_o]

You have 2 choices:

The simple way : Indeed, send a constant value of 4.6 celsius to BSEC with each datapoint, knowing that the output will wrong until your board has actually heated up.
The accurate way : You can model the thermal response of your module using a reference ambient sensor. Use this model to get a good BSEC_INPUT_HEATSOURCE estimation.

If your device is always-on and boot times of a few minutes do not scare you, then the simple way may provide an acceptable output for your use-case. If you have multiple heat sources (CPU, wireless chip, Battery charger, display, etc) which are not constant, then modelling the thermal behavior of your design is essential, if the BME680 cannot provide an accurate measurement using placement alone
o_o

[rindler]

Thanks again for your reply. Yes, it is always on and I want to use the simple way with just sending a constant, but I don't get how I should write it since #define BSEC_INPUT_HEATSOURCE 4.6; is not working. Any other suggestions?