BME688 Development board (Adafruit + 8xBME688) - Temperature sensor - offset of 5 degrees+

[fpineau]

Hello, 

On my project, we would to use the BME688 4 in 1 sensor. I already test the COV, humidity and pressuee part.
And now I work on the temperature sensor BME688. So, I'm posting here because I want to have more information about the data of this temperature sensor.
I see that in the datasheet the accuracy of this sensor is +/-0.5°C between 0-65°C.

So for my tests, I did some run with the development board ( Adafruit + 8 BME688) and I put the board in a fidge at 15°C (with a variation of 0.3°C).
You can see below a 4 days run with the heater profile HP-322 / RDC-3-12. 

We can see that we have an offset of 5°C. We are far that the accuracy of  +/-0.5°C between 0-65°C.
Also I see that this offset change with the heater profile.

So my questions are : Where come from the offset of 5°C ? And I how I can fix it ?

Thank you for your precision.

Florian

[fpineau]

Hello Robin,

Thank you for the answer. 

And if I use an other CPU than ESP for controling the BME688 (Exemple: EFR32 form silabs). So, I just need to take the value from "temp_xlsb", "temp_lsb" and "temp_msb" , make the calcul below and add 5 to the data "temp_comp". It is right? 

Have a nice day.

Best regards!
Mister fpineau

[BSTRobin]

Hi fpineau,

No. You need to refer previous comment to modify offset.