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    BME 680 IAQ accuracy abnormal operation

    adam_smith
    New Poster

    BME 680 IAQ accuracy abnormal operation

    Hi,

    I am working with a BME680 VOC sensor on a project and I have detected some abnormal performance while reading values for a long time.

    My setup is as follows:

    - BSEC 1.4.8.0 Normal Version

    - generic_18v_300s_4d config operation

    - I have a sensor calibrated as indicated in the manual: about 30 minutes exposed to fresh air and another 30 minutes in a box with exhaled breath. During this calibration process I was able to see how the IAQ accuray went from  index 0 to index 3.

    - Location: Indoor office

    After that, I was reading some values that were more or less correlated with measurements taken from other VOC sensors that we were using as a reference. However, at some point in time, BME680 took some wrong value and started a recalibration (index 2) until new calibrated values were obtained.

    Here you can find a snapshot of the logs:

    [05:23:17.046] T, 24.52, rH, 30.85, Pa, 93866.99, IAQ, 128.94 (3), Static IAQ, 110.07, CO2e, 1100.71 (3), bVOC, 1.80 (3)
    [05:23:20.052] T, 24.51, rH, 30.93, Pa, 93863.14, IAQ, 129.27 (3), Static IAQ, 110.33, CO2e, 1103.35 (3), bVOC, 1.81 (3)
    [05:23:23.058] T, 24.52, rH, 30.90, Pa, 93866.49, IAQ, 128.77 (3), Static IAQ, 109.92, CO2e, 1099.20 (3), bVOC, 1.80 (3)
    [05:23:26.064] T, 24.52, rH, 30.94, Pa, 93865.57, IAQ, 128.38 (3), Static IAQ, 109.60, CO2e, 1096.01 (3), bVOC, 1.79 (3)
    [05:23:29.070] T, 24.52, rH, 30.95, Pa, 93866.09, IAQ, 132.40 (3), Static IAQ, 112.89, CO2e, 1128.92 (3), bVOC, 1.88 (3)
    [05:23:32.076] T, 24.51, rH, 30.95, Pa, 93862.64, IAQ, 153.91 (3), Static IAQ, 130.48, CO2e, 1304.86 (3), bVOC, 2.46 (3)
    [05:23:35.082] T, 24.52, rH, 30.93, Pa, 93866.60, IAQ, 174.60 (3), Static IAQ, 147.41, CO2e, 1474.13 (3), bVOC, 3.18 (3)
    [05:23:38.088] T, 24.52, rH, 30.97, Pa, 93864.11, IAQ, 189.91 (3), Static IAQ, 159.93, CO2e, 1599.35 (3), bVOC, 3.84 (3)
    [05:23:41.094] T, 24.52, rH, 30.96, Pa, 93865.80, IAQ, 212.69 (3), Static IAQ, 178.56, CO2e, 1785.64 (3), bVOC, 5.09 (3)
    [05:23:44.100] T, 24.52, rH, 30.95, Pa, 93865.80, IAQ, 236.98 (3), Static IAQ, 198.43, CO2e, 1984.37 (3), bVOC, 6.87 (3)


    [05:23:47.106] T, 24.52, rH, 30.95, Pa, 93865.85, IAQ, 264.75 (2), Static IAQ, 221.86, CO2e, 2218.62 (2), bVOC, 9.80 (2)
    [05:23:50.112] T, 24.52, rH, 30.95, Pa, 93865.07, IAQ, 312.35 (2), Static IAQ, 261.79, CO2e, 2617.94 (2), bVOC, 17.92 (2)
    [05:23:53.118] T, 24.52, rH, 30.97, Pa, 93865.98, IAQ, 369.26 (2), Static IAQ, 309.70, CO2e, 3097.06 (2), bVOC, 36.98 (2)
    [05:23:56.124] T, 24.53, rH, 30.98, Pa, 93866.55, IAQ, 427.10 (2), Static IAQ, 358.71, CO2e, 3587.18 (2), bVOC, 77.59 (2)
    [05:23:59.130] T, 24.52, rH, 31.03, Pa, 93865.92, IAQ, 471.39 (2), Static IAQ, 396.78, CO2e, 3967.88 (2), bVOC, 137.96 (2)
    [05:24:02.136] T, 24.53, rH, 31.02, Pa, 93865.97, IAQ, 489.92 (2), Static IAQ, 413.58, CO2e, 4135.87 (2), bVOC, 177.84 (2)
    [05:24:05.142] T, 24.52, rH, 30.98, Pa, 93864.74, IAQ, 491.81 (2), Static IAQ, 416.52, CO2e, 4165.27 (2), bVOC, 185.92 (2)

    [05:24:29.190] T, 24.53, rH, 30.87, Pa, 93868.17, IAQ, 500.00 (2), Static IAQ, 441.76, CO2e, 4417.66 (2), bVOC, 272.29 (2)
    [05:24:32.196] T, 24.54, rH, 30.88, Pa, 93869.30, IAQ, 500.00 (2), Static IAQ, 451.84, CO2e, 4518.46 (2), bVOC, 317.11 (2)
    [05:24:35.202] T, 24.53, rH, 30.87, Pa, 93869.53, IAQ, 500.00 (2), Static IAQ, 455.42, CO2e, 4554.22 (2), bVOC, 334.72 (2)

    .............
    [05:31:02.976] T, 24.54, rH, 30.83, Pa, 93864.33, IAQ, 243.24 (2), Static IAQ, 285.56, CO2e, 2855.62 (2), bVOC, 25.67 (2)
    [05:31:05.982] T, 24.55, rH, 30.86, Pa, 93865.46, IAQ, 242.80 (2), Static IAQ, 285.03, CO2e, 2850.32 (2), bVOC, 25.47 (2)
    [05:31:08.988] T, 24.55, rH, 30.84, Pa, 93865.01, IAQ, 243.85 (2), Static IAQ, 286.27, CO2e, 2862.78 (2), bVOC, 25.95 (2)
    [05:31:11.994] T, 24.55, rH, 30.85, Pa, 93863.44, IAQ, 243.36 (2), Static IAQ, 285.67, CO2e, 2856.76 (2), bVOC, 25.72 (2)
    [05:31:15.000] T, 24.55, rH, 30.83, Pa, 93863.95, IAQ, 242.47 (2), Static IAQ, 284.61, CO2e, 2846.14 (2), bVOC, 25.31 (2)
    [05:31:18.006] T, 24.55, rH, 30.81, Pa, 93864.39, IAQ, 241.47 (2), Static IAQ, 283.40, CO2e, 2834.03 (2), bVOC, 24.85 (2)
    [05:31:21.012] T, 24.55, rH, 30.78, Pa, 93865.75, IAQ, 241.06 (3), Static IAQ, 282.90, CO2e, 2829.09 (3), bVOC, 24.66 (3)
    [05:31:24.018] T, 24.55, rH, 30.78, Pa, 93864.90, IAQ, 240.78 (3), Static IAQ, 282.57, CO2e, 2825.71 (3), bVOC, 24.54 (3)
    [05:31:27.024] T, 24.55, rH, 30.78, Pa, 93865.99, IAQ, 240.46 (3), Static IAQ, 282.17, CO2e, 2821.70 (3), bVOC, 24.39 (3)
    [05:31:30.030] T, 24.55, rH, 30.81, Pa, 93863.61, IAQ, 241.72 (3), Static IAQ, 283.66, CO2e, 2836.67 (3), bVOC, 24.95 (3)
    [05:31:33.036] T, 24.55, rH, 30.84, Pa, 93864.17, IAQ, 241.62 (3), Static IAQ, 283.54, CO2e, 2835.40 (3), bVOC, 24.90 (3)
    [05:31:36.042] T, 24.55, rH, 30.86, Pa, 93864.39, IAQ, 241.94 (3), Static IAQ, 283.91, CO2e, 2839.14 (3), bVOC, 25.04 (3)
    [05:31:39.048] T, 24.55, rH, 30.88, Pa, 93864.28, IAQ, 242.02 (3), Static IAQ, 283.99, CO2e, 2839.94 (3), bVOC, 25.07 (3)
    [05:31:42.054] T, 24.55, rH, 30.91, Pa, 93864.06, IAQ, 242.32 (3), Static IAQ, 284.34, CO2e, 2843.48 (3), bVOC, 25.21 (3)
    [05:31:45.060] T, 24.56, rH, 30.91, Pa, 93865.12, IAQ, 242.10 (3), Static IAQ, 284.07, CO2e, 2840.73 (3), bVOC, 25.10 (3)
    [05:31:48.066] T, 24.55, rH, 30.92, Pa, 93864.23, IAQ, 241.52 (3), Static IAQ, 283.37, CO2e, 2833.76 (3), bVOC, 24.84 (3)
    [05:31:51.072] T, 24.56, rH, 30.90, Pa, 93866.09, IAQ, 241.65 (3), Static IAQ, 283.52, CO2e, 2835.21 (3), bVOC, 24.89 (3)
    [05:31:54.078] T, 24.56, rH, 30.90, Pa, 93865.29, IAQ, 240.92 (3), Static IAQ, 282.63, CO2e, 2826.39 (3), bVOC, 24.56 (3)

    As you can see, we are working in a controlled area with around 1000ppm CO2 values. This concentration values did not change throughout the test (we know this because other VOC sensors gave us CO2 concentration values around 1000ppm throughout the test). However, as you can see, the BME680 started to provide some abnormally high CO2 values (it even hit an IAQ of 500!), began a recalibration, and after that it provided abnormal unrealistically high IAQ, CO2e, and bVOC values.

    We don't undertand why the sensor suddenly started showing these strange values. We are planning to use this sensor to monitor Air Quality in critical areas and we can't afford to provide erroneous values.

    Have you experienced something like this? Could it be a bug within BSEC library? Do you have any suggestions on what may be going on?

    Regards

     

    10 REPLIES 10
    BSTRobin
    Community Moderator

    Re: BME 680 IAQ accuracy abnormal operation

    Hello adam_smith,

    Are they IAQ accuracy innside the red rectangle?

    BSEC log.png

    adam_smith
    New Poster

    Re: BME 680 IAQ accuracy abnormal operation

    Hi,

    Yes, They are the IAQ accuracy. Every number in parentheses is the accuracy associated with the value displayed immediately to its left.

    Thanks

    BSTRobin
    Community Moderator

    Re: BME 680 IAQ accuracy abnormal operation

    Hello adam_smith,

    Do you have full log file to check?

    adam_smith
    New Poster

    Re: BME 680 IAQ accuracy abnormal operation

    Hello,

    Attached you can find the log file that we have. The key is that for the entire indicated time the environment remains at a CO2 concentration of around 1000ppm, but we do not know why the sensor begins to calibrate again.

    Thanks

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