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    BME280 wrong values from humidity sensor

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    Member

    BME280 wrong values from humidity sensor

    We use your sensor BME280 for one of our products. We have made a hardware modification to our product and produced a prototype series with the adapted PCB . With the first 10 pieces everything works, except that the sensor returns wrong humidity values. But the temperature and the air pressure have realistic normal values. With the exact same software on the old PCB I get the correct humidity values. The scheme is identical for both versions.
    Can you explain this? We have already replaced the supposedly defective sensors and got the same result again.

    Best Regards

    Loris De Fina

    8 REPLIES 8
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    Community Moderator

    Re: BME280 wrong values from humidity sensor

    Hi,

    Thanks for your inquiry.

    You said that on your old PCB BME280 gives correct humidity results, but on your new PCB with the same software BME280 gives wrong humidity values. This could be contamination inside the new BME280 during your PCB assembly.

    Please let us know which country you are located in. Our local FAE can contact you for further failure analysis.

    Thanks.

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    Member

    Re: BME280 wrong values from humidity sensor

    Our company is seated in switzerland. We replaced the sensor and made sure it wasn't contaminated. Did Bosch changed something for calculating the humidity in the last 2 years?

    Best Regards

    Loris De Fina

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    Community Moderator

    Re: BME280 wrong values from humidity sensor

    No, the humidity calculate formula is not changed.

    You can also refer to our latest API on Github for more detail. 

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    Member

    Re: BME280 wrong values from humidity sensor

    So then I have no clue what I am doing wrong. As i said before we have a hardware which works with the BME 280. We had to change the dimensons of the PCB and took some parts off of the PCB which resulted in the prototype series which have the problem with the humidity sensor. The same software works with the old but not with the new PCB. We also changed the working sensor on the old PCB with one from the reel we made the prototypes which are currently not working. The result was that the old hardware doesn't work with the changed sensor. We also ordered sensors from a different distributor but it didn't changed the fact that the sensor gives back the wrong humidity values. Always in the range from 85%-100%. All the prototypes give different results in this range but they are all on my desk and should give the same value +- the humidity tolerance.

    Best Regards

    Loris De Fina

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