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    BME680 eCO2 accuracy

    liamm36
    New Poster

    Re: BME680 eCO2 accuracy

    Hey BSTRobin,

    apologies for the delayed response. In the original firmware we did not log gas resistance at all. I have been experiementing both in Arduino and esp-idf and have found the BSEC_OUTPUT_RAW_GAS measurement to be static. 

    I have also tried running the stock arduino bsec library example https://github.com/BoschSensortec/BSEC-Arduino-library/blob/master/examples/basic/basic.ino and got the same results on our custom hardware and on a adafruit bme680 dev board found at https://www.mouser.co.uk/new/adafruit/adafruit-bme680-dev-board/

    The following is a sample arduino example output

    Time ,raw Temp, Press,raw  Hum,  Gas resistance, IAQ, acc, temp, humidity, static iaq, co2equiv, breathVocEquivalent

    1737036, 23.75, 101385.00, 36.38, 12887828.00, 85.26, 1, 23.69, 36.52, 51.32, 605.30, 0.74
    1740036, 23.75, 101379.00, 36.36, 12887828.00, 85.71, 1, 23.69, 36.50, 51.52, 606.09, 0.75
    1743036, 23.75, 101379.00, 36.35, 12887828.00, 86.16, 1, 23.69, 36.49, 51.72, 606.87, 0.75
    1746036, 23.75, 101379.00, 36.34, 12887828.00, 86.60, 1, 23.69, 36.48, 51.91, 607.64, 0.75
    1749036, 23.74, 101379.00, 36.34, 12887828.00, 87.04, 1, 23.68, 36.50, 52.10, 608.41, 0.75
    1752037, 23.74, 101383.00, 36.34, 12887828.00, 87.46, 1, 23.68, 36.50, 52.28, 609.13, 0.76
    1755037, 23.75, 101381.00, 36.34, 12887828.00, 87.84, 1, 23.69, 36.47, 52.45, 609.79, 0.76
    1758036, 23.74, 101383.00, 36.36, 12887828.00, 88.20, 1, 23.68, 36.51, 52.61, 610.43, 0.76
    1761036, 23.74, 101383.00, 36.36, 12887828.00, 88.54, 1, 23.68, 36.51, 52.76, 611.03, 0.76
    1764037, 23.74, 101381.00, 36.36, 12887828.00, 88.87, 1, 23.68, 36.51, 52.90, 611.60, 0.76
    1767037, 23.74, 101381.00, 36.37, 12887828.00, 89.17, 1, 23.68, 36.52, 53.03, 612.13, 0.76
    1770037, 23.74, 101381.00, 36.38, 12887828.00, 89.45, 1, 23.68, 36.52, 53.15, 612.62, 0.77
    1773037, 23.74, 101381.00, 36.40, 12887828.00, 89.70, 1, 23.68, 36.55, 53.26, 613.04, 0.77
    1776037, 23.74, 101383.00, 36.40, 12887828.00, 89.93, 1, 23.68, 36.54, 53.36, 613.46, 0.77
    1779037, 23.75, 101385.00, 36.41, 12887828.00, 90.12, 1, 23.69, 36.53, 53.45, 613.79, 0.77
    1782037, 23.74, 101385.00, 36.44, 12887828.00, 90.30, 1, 23.68, 36.58, 53.52, 614.09, 0.77
    1785037, 23.74, 101385.00, 36.44, 12887828.00, 90.46, 1, 23.68, 36.59, 53.59, 614.38, 0.77
    1788037, 23.74, 101383.00, 36.44, 12887828.00, 90.61, 1, 23.68, 36.59, 53.66, 614.64, 0.77
    1791037, 23.74, 101385.00, 36.45, 12887828.00, 90.74, 1, 23.68, 36.60, 53.72, 614.88, 0.77
    1794037, 23.74, 101385.00, 36.45, 12887828.00, 90.88, 1, 23.68, 36.59, 53.78, 615.11, 0.77
    1797037, 23.73, 101383.00, 36.45, 12887828.00, 91.02, 1, 23.67, 36.61, 53.84, 615.36, 0.77
    1800037, 23.73, 101383.00, 36.43, 12887828.00, 91.19, 1, 23.67, 36.58, 53.91, 615.65, 0.77
    1803037, 23.73, 101383.00, 36.42, 12887828.00, 91.36, 1, 23.67, 36.57, 53.99, 615.95, 0.77
    1806037, 23.72, 101383.00, 36.40, 12887828.00, 91.55, 1, 23.66, 36.57, 54.07, 616.29, 0.78
    1809037, 23.72, 101387.00, 36.41, 12887828.00, 91.74, 1, 23.66, 36.57, 54.15, 616.61, 0.78
    1812037, 23.73, 101383.00, 36.41, 12887828.00, 91.88, 1, 23.67, 36.55, 54.22, 616.87, 0.78
    1815036, 23.72, 101387.00, 36.38, 12887828.00, 92.08, 1, 23.66, 36.54, 54.30, 617.21, 0.78
    1818037, 23.72, 101387.00, 36.40, 12887828.00, 92.25, 1, 23.66, 36.55, 54.38, 617.51, 0.78
    1821037, 23.72, 101387.00, 36.39, 12887828.00, 92.42, 1, 23.66, 36.54, 54.45, 617.80, 0.78
    1824037, 23.71, 101385.00, 36.40, 12887828.00, 92.60, 1, 23.65, 36.56, 54.53, 618.11, 0.78
    1827037, 23.72, 101385.00, 36.38, 12887828.00, 92.76, 1, 23.66, 36.53, 54.60, 618.40, 0.78

    As you can see the gas resistance does not change even though the co2 and voc is updated and should be based on the gas resistance?

    Note even after several days of running the gas resistance does not change.

    All these tests have been run on ESP-32 microcontrollers. 

    Thank you,

    Liam

     

     

     

    BSTRobin
    Community Moderator

    Re: BME680 eCO2 accuracy

    Hi liamm36,

    Thanks for your feedback.
    After our internal discussion, it look likes gas is in resistant saturation situation, please check below information,
    1.Check the sensor heater if work or not, or use different heater temperature to check.
    2.Use another BME680 sensor to check if have same phenomenon.

    BSTRobin
    Community Moderator

    Re: BME680 eCO2 accuracy

    Hi liamm36,

    Do you have further feedback?

    BSTRobin
    Community Moderator

    Re: BME680 eCO2 accuracy

    Since there was no feedback for a long time, we close this topic first. You could update feedback in the future if you have.

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