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    BMI 270 is not responding in SPI 4wire mode

    BMI 270 is not responding in SPI 4wire mode

    joma
    Established Member

    Hello,

    For evaluation we ordered Shuttle Board BMI270 (Shuttle Board BMI270 Bosch Sensortec | Mouser Slovakia).
    We want to use 4wire SPI mode for communication. In this mode BMI270 is not responding to read chip ID (always returning 0).

    Shuttle Board BMI270 is connected with IMX6 running Linux, pinout is following:
    Pin 1,2 – VCC (3.3V)
    Pin 3 – GND
    Pin 4 – MISO
    Pin 4 – CS
    Pin 16 – MOSI
    Pin 18 – CLK
    Pin 20 – IRQ
    Jumpers are removed.

    SPI frequency is set to 100kHz for testing. CS is low during SPI communication with BMI270.
    I am trying to read register 0 (first write 0x80 on SPI, then read 8 bit).
    During communication I don’t see any activity on MISO line – it is always low. Do I need to do any special startup procedure ?

    Thanks

    5 REPLIES 5

    Minhwan
    Community Moderator
    Community Moderator

    Hello Joma, 

     

    Here is the BMI270 datasheet, and there is our interface requirements in page 129. 

    bst-bmi270-ds000.pdf

    I'm not sure whether your interface is for SPI because 100khz is quite slow than usual. 

    If your interface is for SPI, could you test with higher speed like 2Mhz? 

    Thanks, 

     

    joma
    Established Member

    With 3 MHz it is the same. No activity on MISO line.

    Minhwan
    Community Moderator
    Community Moderator

    Hello Joma, 

     

    I think there is some interface issue. 

    You can write softreset for test. 

    Reg 0x7E value 0xB6 and delay 150ms before trying to read data from register 0x00.  

    If your interface is okay, MOSI shall transmit 0xB6 value to Register 0x7E. 

    If not, need to check hardware side. 

    Thanks, 

     

    joma
    Established Member

    Same issue. 

    Is my Shuttle Board BMI270 wiring correct ? Is everything required connected or do I need to ground some unused pins ?

    During IMX6 startup CS pin is changed several times (when uboot/linux reconfigures pinmux) - can be this problem ?

    Thanks.

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