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BME280 fail

2024-09-23
2024-09-24
  • Dave Wilkes

    Dave Wilkes - 2024-09-23

    Hi guys do you know what would cause my BME280's to fail?
    one will work for a few days then become unresponsive and the admin pages says not found!
    fit a new one and that will work for a while !
    had 4 fail now

     
  • brownrb

    brownrb - 2024-09-24

    Hi Dave

    Which connection did you use? Assuming you are using a PCB?
    J8 has 3.3V
    The sensor itself is rated as

    The sensor provides both SPI and I²C interfaces and can be supplied using 1.71 to 3.6 V for the
    sensor supply VDD and 1.2 to 3.6 V for the interface supply VDDIO.

    So using 5V to power the sensor is not the best idea. Some modules allow the use of 5V but some do not.

    Also make sure that it it not a BME280P sensor as this has issues. Eg it does not measure humidity.

    Make sure that C6 and C5 are fitted, C6 is there to reduce noise and C5 is there to smooth any glitches in the power supply.

    I would also check gnd continuity by ensuring that all gnd points are at the same potentional, as any ground loop will kill the sensor.

    The BME is very sensitive to dew and humidity or rain. It will definately stop working if affected by these. This is the reason I suggested to mount underneath the case.

    Check that the metal case of the sensor does not touch anything metallic so it does not create a pathway between the sensor case and anything that has gnd or +v voltage.

    On the application note for BME sensor, there is a note about re-conditioning the sensor if it gets exposed to rain/humidity

    The pdf has mention of this

    When exceeding the operating range (e.g. for soldering), humidity sensing performance is
    temporarily degraded and reconditioning is recommended as described in section 7.8.
    Operating range only for non-condensing environment

    7.9 Reconditioning Procedure
    After exposing the device to operating conditions, which exceed the limits specified in
    section 1.2, e.g. after reflow, the humidity sensor may possess an additional offset. Therefore
    the following reconditioning procedure is mandatory to restore the calibration state:
    1. Dry-Baking: 120 °C at <5% rH for 2 h
    2. Re-Hydration: 70 °C at 75% rH for 6 h

    or alternatively
    1. Dry-Baking: 120 °C at <5% rH for 2 h
    2. Re-Hydration: 25 °C at 75% rH for 24 h

    or alternatively after solder reflow only
    1. Do not perform Dry-Baking
    2. Ambient Re-Hydration: ~25 °C at >40% rH for >5d

    Regards
    Robert

     
  • Dave Wilkes

    Dave Wilkes - 2024-09-24

    hi Robert thanks for that I will check those things
    I am using the pcbbut will make sure its 3.3v and the caps are installed.
    currently it's ina dry test environment so not getting moisture.
    best regards

     

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