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    BMI088 Temperature Reading Always 25C (Doesn't change)

    BMI088 Temperature Reading Always 25C (Doesn't change)

    droberson
    New Poster

    Hello again,

    I am having an issue where the BMI088 temperature sensor always reports 25C regardless of how much I heat the board using a heat gun. I have verified that the data coming back from reading registers 0x22 and 0x23 is [0x02, 0x19] respectively. Ie, it is not a logic / code error. (See screenshot below)

    image.png

    Referencing "5.3.7 Temperature sensor data" from the datasheet, the above value calculates out to be 25 C.

    I also made sure the accelerometer is enabled by writing 0x04 to ACC_PWR_CTRL and reading acceleormeter values prior to reading temperature values every 2 seconds since it is updated every 1.28 seconds.

    Data log:

    <info> app: Accel - X: -49, Y: -25, Z: 1361
    <info> app: Accel - X: -52, Y: -16, Z: 1362
    <info> app: Accel - X: -50, Y: -23, Z: 1368
    <info> app: Accel - X: -51, Y: -26, Z: 1365
    <info> app: Accel - X: -54, Y: -19, Z: 1363
    <info> app: Accel - X: -55, Y: -15, Z: 1369
    <info> app: Accel - X: -55, Y: -18, Z: 1363
    <info> app: Accel - X: -53, Y: -21, Z: 1367
    <info> app: Accel - X: -48, Y: -22, Z: 1365
    <info> app: Accel - X: -54, Y: -15, Z: 1363
    <info> app: Accel - X: -51, Y: -19, Z: 1371
    <info> app: Accel - X: -52, Y: -26, Z: 1365
    <info> app: Accel - X: -47, Y: -19, Z: 1358
    <info> app: Accel - X: -48, Y: -14, Z: 1368
    <info> app: Temp: 25 C
    <info> app: Temp: 25 C (2 seconds later)
    <info> app: Temp: 25 C (2 seconds later)
    <info> app: Temp: 25 C (etc...)
    <info> app: Temp: 25 C
    <info> app: Temp: 25 C
    <info> app: Temp: 25 C
    <info> app: Temp: 25 C
    <info> app: Temp: 25 C
    <info> app: Temp: 25 C
    <info> app: Temp: 25 C

    What am I missing? Is the sensor broken?

    Thanks,

    Derek

    2 REPLIES 2

    FAE_CA1
    Community Moderator
    Community Moderator

    Hi,

    Thanks for your inquiry. BMI088 accelerometer temperature sensor is 11 bit with register 0x22 as MSB and register 0x23 upper three bits as LSB. The sensitivity is 0.125C/LSB and 23C when both register 0x22 and 0x23 are 0x00.

    Therefore, register 0x23 can only have the following values: 0x00, 0x20, 0x40, 0x60, 0x80, 0xA0, 0xC0 and 0xE0. But in your case you gotthe value of 0x19 for register 0x23. That means your I2C communication may have some issues.

    Thanks.

    Figured out the issue. I was trying to read the temperature data using the Gyroscope I2C address. Reading with the acceleormeter I2C address works. Oops.

    Thanks for your help.

    Derek

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