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    BME 280 humidity reading less than actual

    BME 280 humidity reading less than actual

    New Poster


    I am working with BME280 sensors for over a year now. I currently have 10 BME280 sensors, all from Adafruit. 

    8 sensors are showing humidity -8% and 2 sensors are showing +12% humidity. I am checking them against the UT333 sensor and handheld psychrometer. 

    I have tried to recalibrate the sensors, by dry baking them in reflow oven at 120c for 2 hours and rehydrating them for 24 hours at 80%+ humidity. 

    After recalibration attempt, 2 sensors that were showing +12% humidity are now showing correct readings. but the remaining 8 sensors which were showing -8% are still showing -8% humidity. 

    How can I fix this? 

    5 REPLIES 5

    Community Moderator
    Community Moderator

    The relative humidity output is within range of 0% - 100%.  there is no possibility to output negative humidity value. 

    The -8% can be caused by compensation / calculation errors in SW.

    Did you able to use the lasest BME280 API on Github?

    If possible,  you can provide all calibration parameters as well as the ADC value from register to us, we can cross check at our side about those parameters first. 

    Apologies for the confusion, I didn't mean value are showing negative. 

    I was saying values are less than actual by 8%.

    When The psychrometer is showing 77% humidity, all 8 BME sensors show 69%. 

    Also, could you please let me know how to use the official API with Arduino? 

    Community Moderator
    Community Moderator

    Sorry, i don't have a working example under Arduino for BME280 right now. 

    But the official API is based on C langurage,  it can be called by Arduino code directly if you just include the head file in your Arduino project. 

    For the 6 sensors with 8% deviation compared to reference sensor output,  did you also compare the temperature output of those sensors? 

    are they output the same temperature value?

    Further more,  i want to double check with you that both sensors are put into same environment, right? 

    @Vincent wrote:

    For the 6 sensors with 8% deviation compared to reference sensor output,  did you also compare the temperature output of those sensors? 

    are they output the same temperature value?

    Sensors with an 8% deviation are showing temperature 0.8 to 1.1 degrees less than the actual temperature.

    I am cross-checking the temperature and humidity with a handheld psychrometer and HTC-206 hygrometer. And yes, all sensors are in the same environment.