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    BMX055 Magnetometer Data Ready Interrupt

    BMX055 Magnetometer Data Ready Interrupt

    BobbyTables
    New Poster

    Hello,

    I'm facing some issues with the bmx055 magnetometer data ready interrupt line. The sensor is mounted on the shuttle board. I want to establish an interrupt based data readout with an ATmega via SPI and it works just fine - but only for some time. After a certain period the magnetometer data ready interrupt just stays high. If I'm lucky than it starts working again, but will fail again, too. I can continue the data readout by polling, but I would like to avoid that solution. I also noticed that the pulse width of the interrupt signal, while working, varies greatly, but the width of the other two for accelerometer and gyroscope remains constant (all in non-latched mode). Is this a known issue or is there a workaround like a reinitialization after some time?

    Normal and advanced self-test seem to be fine, whereas I get margins of up to 50uT. Concerning the magnetometer my initialization routine (without the self-tests & trim data) does the following:

    -set power control bit(set reg 0x48 bit 0)

    -set high precision mode (reg 0x51 write 0x17, reg0x52 write0x29)

    -set to normal mode & ODR to 20Hz(reg 0x4c write 0x28)

    -enable DRDY interrupt, map to pin &active high(reg 0x4e write 0x84)

    After the initialization I do not modify any registers, only updating data and doing some further calculations. Am I missing something?

     

    Much thanks in advance and have a nice weekend!

    9 REPLIES 9

    FAE_CA1
    Community Moderator
    Community Moderator

    Hi,

    Thanks for your inquiry.

    When you set BMX055 magnetometer to high accuracy preset, nXY = 47 and nZ = 83. So you need to write register 0x51 with the value of 0x17 so that nXY = 1 + 2*(0x17) = 47 which is correct. You need to write register 0x52 with the value of 0x52 so that nZ = 1 + 0x52 = 83. But you write it with the value of 0x29. Please try again.

    Thanks.

    Hello,

    thank you for your hint. I changed it, but I see still the same behaviour. I'm attaching some scope screenshots, where you can see the variation in the interrupt behaviour. The MAG pictures were all taken with the same oscilloscope settings. As a reference I add a ACC interrupt picture.

    Edit: Do you get the pictures? I can attach but I don't see them in the post. I added them to my public album just in case.

     

    Thanks

    FAE_CA1
    Community Moderator
    Community Moderator

    Hi,

    Sorry for the late response. I don't see the pictures in your message. Please attach them again.

    Thanks.

    Hello,

    as I said I don't know why they don't appear in the post, although I upload them. I'm trying again.  But in my profile's public album you can have a look at them.

    https://community.bosch-sensortec.com/t5/media/gallerypage/user-id/6362/album-id/1669/tab/albums

    Thanks for your efforts.

     

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