Adafruit library shows different values than BSEC library

[Napsty]

I did some comparison between using the Adafruit CircuitPython BME680 python module and the compiled BSEC library from Bosch (using https://github.com/alexh-name/bsec_bme680_linux) and the values retrieved from the sensor differ.

$ cat adafruit_example.py 
import board
import busio
import adafruit_bme680
i2c = busio.I2C(board.SCL, board.SDA)
sensor = adafruit_bme680.Adafruit_BME680_I2C(i2c)
print('Temperature: {} degrees C'.format(sensor.temperature))
print('Gas: {} ohms'.format(sensor.gas))
print('Humidity: {}%'.format(sensor.humidity))
print('Pressure: {}hPa'.format(sensor.pressure))

Results:

$ python3 adafruit_example.py 
Temperature: 4.6993359375 degrees C
Gas: 1578360 ohms
Humidity: 57.53554887071429%
Pressure: 947.7445084251684hPa

The binary compiled with BSEC library shows different values:

2020-04-02 10:02:13,[IAQ (0)]: 25.00,[T degC]: -0.29,[H %rH]: 82.23,[P hPa]: 947.72,[G Ohms]: 104297,[S]: 0,[eCO2 ppm]: 500.000000000000000,[bVOCe ppm]: 0.4999999403953552246093750

Temperature: BSEC is right. I know it's currently below 0 outside.
Humidity: BSEC is more rightish, when I compare the Live Weather maps (https://kachelmannwetter.com/de/analyse/superhd/thurgau/luftfeuchtigkeit/20200402-0720z.html). The reading from 40 mins ago says between 70 and 80% humidity where I live.
Pressure: Both values are the same, look correct
Gas: Large difference! 104297 from BSEC and 1578360 from Adafruit

Are the calculations/calibrations in the Adafruit library incorrect? Do you have a partnership with Bosch to take a closer look at this?

Screenshot humidity map for comparison:

[evaherrada]

So the part of this library that is causing this issue is much more complicated than I initially assumed it would be. However, there is a really easy fix for the temperature. It seems like it is usually off by 5 degrees C, so we should just subtract 5 from it like the library you linked does.

[evaherrada]

@Napsty I've made a PR that ought to fix the temperature issue, although I haven't tested it. Do you think you might be able to test it and see how it compares to the BSEC library?

[jposada202020]

@Napsty Hello :), have you been able to test this? thanks

[Napsty]

Sorry - no, was not able to test yet. The BME680 sensor is still in daily use and I hope I will find a couple of hours to test this but currently busy on other things.

[FoamyGuy]

closing this for now, I believe it should be resolved by #32. If you get back to it and are still having trouble you can re-open.