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    BME280 incorrect readings

    BenShapiro
    New Poster

    BME280 incorrect readings

    Hi,

    I have BME280 on custom board connected to CC1350 host via I2C.

    I configure BME280 to normal mode. When I read temperature right after power down I get at the first read correct values, then second read the value is about 25% higher than first read, and third read the value is about 50%-70% higher then in the first read, and I am sure the readings are incorrect.

    What could be the cause for such behaviour?

    Regards

    6 REPLIES 6
    FAE_CA1
    Community Moderator

    Re: BME280 incorrect readings

    Hi,

    Thanks for your inquiry.

    I think you may mean you read temperature data after power on, not power down. The temperature data should be stable, not increasing 25% and 50%. Please refer to BME280 API source code at https://github.com/BoschSensortec/BME280_driver about how to initialize BME280 and how to read sensor data.

    Thanks.

    BenShapiro
    New Poster

    Re: BME280 incorrect readings

    Hi,

    I am working with a driver provided in SDK by Texas Instruments, I guess this a working driver. 

    Can this beahviour happen because some HW conditions? over heating, incorrect voltage etc... 

    Or do you think this is a SW problem? 

    FAE_CA1
    Community Moderator

    Re: BME280 incorrect readings

    Hi,

    Yes, this should be SW problem.

    If you initialize BME280 correctly with normal mode, oversampling for T, H and P sensors, then you can use the attached "sample_calculation_BME280.xlsx" to verify your SW. For example, you can manually type trimmed values from the BME280 chip that you are working with into the Excel file dig_T1 to T3, dig_P1 to P9 and dig_H1 to H6 cells. Then every time when you get the unsigned integers raw data for T, H and P sensors, you can manually type the values into the UT, UP and UH cells. The Excel file will calculate the final T in C, final H in %RH and final P in Pa. Then you can compare the results against what you get from the SDK from TI. If they match, then your SW is OK. Otherwise, there is a problem in your SW.

    Thanks.

    Minhwan
    Community Moderator

    Re: BME280 incorrect readings

    Hello BenShapiro,

     

    At early part of data reading, if there is 40 ms delay, could you put some delay and request to read some data? 

    Thanks, 

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