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    BME688 not giving gas readings

    boydy
    Member

    BME688 not giving gas readings

    Hi

    I am developing a lightweight sensor board which contains the BME688.

    I am looking to implement the forced read mode, and have written code that I believe reflects the quick start.

    I am using the sensor with SPI and can communicate with the device, and am writing the code as a bare metal implementation in C.

    I am also able to read back any register value, and am getting values for temp, pressure and humidity - but nothing for gas resistance.

    The gas_r_lsb register is reporting 0x04, which suggests that the device has not achieved the heating current - yet no changes of times or target currents seem to change this.

    I have read back the registers in the device, and they all appear to be as expected. I have also observed that the current draw from the device does inrease if the heating time is increased, as I can see the linear device that powers it warm up by a few degrees with a thermal camera when the time is extended.

    As an experiment I also switched the device into paralell mode, but this made no difference to the output.

    What am I missing?

    Ta!

    Tags (3)
    4 REPLIES 4
    BSTRobin
    Community Moderator

    Re: BME688 not giving gas readings

    Hello boydy,

    According your description, suggest you use BSEC1 for your reference, BSEC1 package contained BME68X driver code, BSEC library, integration guide. You could download it from here: https://www.bosch-sensortec.com/software-tools/software/bsec/

    boydy
    Member

    Re: BME688 not giving gas readings

    Hi BSTRobin (we share a first name :-))

    I have just downloaded the BSEC package, and I'm not sure I can make it work - I am using a PIC processor in my application, which is not supported by the pre-compiled library.

    I note a comment about the supply voltage requiring a compensation for the self heating - I am running at 1.8v on my board, do I need to change the calculation for the target heater current?

    Thanks!

    boydy
    Member

    Re: BME688 not giving gas readings

    I am still struggling to get any sense out of this, is there any more information available?

    Thanks!

    BSTRobin
    Community Moderator

    Re: BME688 not giving gas readings

    Hello boydy,

    You could check the following supported platform document to see if you host MCU could compile BSEC library.
    https://www.bosch-sensortec.com/media/boschsensortec/downloads/bsec/bsec1_binary_size_information.pd...

    If your host MCU and compiler didn't match the document list. you could visit https://www.bosch-sensortec.com/about-us/contact/contact-form, and use the contact form to submit your application.

    From BSEC integration guide, 1.8V was also supported.

    BSEC configurations.png

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