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    BME280/BME680 Pressure Readings

    BME280/BME680 Pressure Readings

    Occasional Visitor

    I have a BME280 and a BME680 sensor and get reasonable readings for temperature and humidity (and gas). But the pressure is always around 955 hPa; +/- 2 hPa. Both, BME280 and BME680, measures always the same constant pressure (only the decimal place differs).

    I use the official examples, also the BSEC example. Tried also some Python examples from the web, same result. Temperature, humidity (and gas) are ok, pressure always constant.

    I have no clue why only the pressure is not valid, e.g. constant. What do I wrong?

    Appreciate any help, hint, …

    Thanks in advance


    5 REPLIES 5

    Occasional Contributor

    Since both pressure sensors measured the same value, the value is exactly the current environmental pressure. Also, the unit is hpa, so the changes in decimal places are acceptable.

    Well I have something similar.

    I have BME680 purchased in the form of a Seeed Studios Grove style sensor board, supported by a Arduino MCU.
    my temp and RH readings look OK, and agree with data published by the weather bureau. But pressure differs.
    weather bureau say it us 1020 hPa /mBAR, but my device says its 1001 hPa. The difference in values is more or less consistent.
    My altitude is 96 metres above mean sea level, I do not know if this would account for the difference.
    What formula can I use to compensate for altitude and temperature ?
    Is there another source of error ?
    Could my device be faulty ? (I see no similar complaints on Seeed forum).

    It is common to observe an "absolute offset" after assembling/mounting the pressure sensor. Such offsets are typically stable over time, which seems to match your observations. Therefore such offsets may be compensated by a one point calibration method (use a calibrated reference device in a stable environment right next to the sensor to estimated your offset, then subtract it from future pressure measurements). Using a calibrated reference device is strongly advised above weather station data to prevent any local weather or altitude changes to influence the measurements.

    Thanks for your response.

    I found that if I use the DFROBOT Library (containing BME680 Library), it provides a more expensive set of functions for the BME 680.  I am able to provide an altitude to calibrate a Sea Level function, and then Fetch pressure compensated for Altitude, and its reasonably accurate.  However when I tried to integrate the DFRobot library into my own sketch, I have run into problems with compilation, the subject of a separate message on this board.