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    BME680: IAQ problem with nRF52840

    BME680: IAQ problem with nRF52840

    Miloslav
    Member

    Hello,

    I am using BME680 with nRF52840 (ARM Cortex M4 with FPU). IDE: Segger Embedded Studio. Compiler: gcc. Normal version of BSEC, Cortex M4F.

    Temperature and humidity metering works just fine. BSEC status is OK. But IAQ accuracy remains 0, IAQ remains 25, CO2 equivalent remains 500. Running LP mode. Tried to wait more than hour for sensor to initialize.

    Attached file bme_user.c is done according to provided bsec_iot_example.

    I found this example in community topic https://community.bosch-sensortec.com/t5/MEMS-sensors-forum/BME-680-IAQ-stuck-at-25-and-accuracy-alw...

    Attacehd file bme_user_modified.c is done according to community topic - It is adding bsec_update_subscription(), bsec_serialized_configurations_iaq - generic_33v_3s_4d and changing config_load()

    Am I missing anything? Could you please help?

    Thanks,

    Miloslav

    9 REPLIES 9

    Jet
    Occasional Contributor

    Hi Sir:

         I think you should have a try to change your timestamp, currently I only suspect it.

         Did you use mark pen or other gases to stimulate BME680 after power on 5 minutes?

     

    Hi Jet,

    Sorry it was my mistake. File bme_user_updated.c ‏, which was in my initial post works. During testing I accidentaly changed Low Power Mode to Continous. Bluetooth stack is running in my apllication. I tried to turn the stack off. When Bluetooth was turn off IAQ metering worked even in Contious mode. Than I realized I set wrong metering mode and changed it to Low power mode. Now it works even with Bluetooth. Thank you for your support.

    I have one more question.

    I plan to use BME680 to meter/analyze CO2 and IAQ in flats and houses. Devices will be placed in one place for long periods(months or years). Which configuration/metering period would you recommend to achieve maximum accuracy? Is there a way to manualy (by code) start calibration when IAQ accuary level is not 3?

    Thanks.

    Jet
    Occasional Contributor

    Hi Sir:

         LP mode is ok and regarding 4d or28d configuration you should know the sensor placed where the airflow change speed is slow or fast.

         Don't need a way to manualy (by code) start calibration when IAQ accuary level is not 3, only keep air quality changed and calibartion will be executed by BESC algorithm.

     

    Hi Jet,

    BME will be placed in one room of a house. Staticaly pluged in electrical socket. I can not guarantee change in air quality. Is there a way to start calibration by code or keep IAQ accuracy level at 3? I do not want to wait for air quality change and loose data.

    For slow airflow change speed is recomended 4d or 28d configuration?

    Thanks,

    Mila

    Jet
    Occasional Contributor

    Hi Sir:

        I am not sure that how long the accuracy reachs to 3 with slow airflow change speed.

        BESC output is only a relative value, indicate the current environment become worse or better with the previous time, so it must know what is bad and good.

       If you want to get  accuracy 3, air quality change has to be meet.

      

     

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