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    General questions about BME680

    Napsty
    Member

    Re: General questions about BME680

    Hello @handytech

    I've kept the sensor running for more than one week now to let it calibrate properly.

    On positive notes: Temperature, Humidity and Pressure seem to give very accurate readings. Nice!

    However I am kind of confused by the raw gas readings (resistance in ohm). Even these resistance values seem to be dependable on the humidity. I see that during the night (with high humidity) the resistance shows  extreme changes (from 95K to 4.6M). Only in the last 2 days seem to be more "stable".

    My problem is how am I able to represent a "correct" air quality when even the raw gas values change because of humidty? The IAQ value from BSEC can only be used when humidity has stabilized during the day. If I want to try and create my own calculation, this is still based on the raw resistance values but they too, are obviously impacted by humidity. Does that even make sense?

    Any thoughts on this?

    handytech
    Community Moderator

    Re: General questions about BME680

    It is hard to comment without reference or absolute sensor, but I would say that your observations make sense. In general it is known that ambient humidity will impact gas sensing, which is compensated for in our IAQ calculation algorithms. Please note that VOC (and other pollutant) compounds and concentrations vary between outdoor and indoor use-cases, and expect our current outputs to perform optimally indoor for stationary applications.

    vraifluss
    New Poster

    Re: General questions about BME680

    I am new to this sensor. wanted to use SPI interface.

    To use SPI interface,the 2 registers were set as below,

    0x75 address sets  0x1(spi_3w_en) and

    0x72 address sets to 0x40(spi_3w_int_en), and then SPI_Data from sensor is stopping to come out.

    without this configuration, at least SPI_data is coming out from sensor.

    Can anyone help how to set SPI Configuration?

    Vrai

     

     

     

    vraifluss
    New Poster

    Re: General questions about BME680

    The ID from page 0 is readable in SPI interface. trying to read the oversampling registers on page 1 register mem ,after page1 mem is set and writing control data as required. read register values are expected as write data, but read values are always all "0xFF". My question is if the control registers are readable or not? datasheet doesnot say anything about thta.Can anyone help ? Assumed that the SPI interface is established due to The Check ID register was written and the result was correct as ID , 0x61.

    Vrai.

     

      

     

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