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    BME680 IAQ fixed value up to 100 measurements

    BME680 IAQ fixed value up to 100 measurements

    New Poster

    Hi there:

    I am using a BME680 with BSEC library and I have some problem with the IAQ values.  IAQ value start at 25 and it is fixed in 25 until after 100 measurements.  Also the iaqAccuracy is 0 until this momemnt. I´m using BSEC_SAMPLE_RATE_LP. 

    Is this behavior normal? I mean, the library take proper values of IAQ and iaqAccuracy only after 100 measurments?

    Thank you in advance,


    5 REPLIES 5

    Community Moderator
    Community Moderator

    Yes, this is normal and expected behavior. When gas measurements are triggered after the BME680 was turned off for some time, the output may need some time to stabilize. This initial period is indicated by an IAQ accuracy of 0 (and a fixed IAQ output if no state file is loaded) for a duration 5 minutes in LP mode (i.e. 5*60/3=100 samples), or 20 minutes in ULP mode.


    Thank you so much for clarifying my doubt @handytech ! So, if I load a state file the IAQ value can variate, although the accuracy will be 0 until after 5 min in LP mode. Isn´t it?

    Community Moderator
    Community Moderator

    Exactly, the initial run in period will still be indicated by an IAQ accuracy of 0 since performance may not be optimal yet, but if a valid state was loaded (and ideally the state was saved when accuracy was at 3) you will already observe some changes in the IAQ output during the first few minutes .

    Please can you elaborate on how the initial period is being tracked by the code, i have the sensor with an esp8266 that crashes and reboots every couple of minutes but the sensor power stays on regardles, what is my understanding from your reply is that I will never get out of the initialization [if that's the right term to use]. That agrees with my readings that have been always 25. 


    I am using codes from the basic Arduino example but inside my home automation device and code.