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BQ40Z50-R1: BQ40Z50-R1 I2C read date abnormal randomly

Star Xu
Genius 9645 points
Part Number: BQ40Z50-R1
Other Parts Discussed in Thread: BQ40Z50, BQSTUDIO, EV2400

Hi

The customer design with BQ40z50-r1,they use STM32F103 to communicate with BQ40Z50 based on software I2C.

During the communication process, they can read normal data, but there will always be occasional abnormal values. 

The communication timing has also changed many kinds of delays, including the timing of bqstudio. The problem now is that normal values ​​can be read, but abnormal values ​​occasionally appear.

Several kinds of abnormal jumps can be caught through the logic analyzer, which should appear randomly.

Attached waveform is reading SOH

The command send is normal, the blue line is SDA .Please help check it.

Waiting for your reply.

Thanks

Star

  • 0
    TI__Guru** 105590 points

    Hello Star,

    What is the clock frequency being used? Also what is the pull-up strength for the bus? Can you also confirm if the abnormal value is being read both by the host and the logic analyzer? Sometimes the analyzer will have additional filters which will not be what BQStudio/host reads.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    TI__Genius 9645 points

    Hi Wyatt

    Thanks for your reply.

    The clock frequnency is about 76kHz, the pull-up resistance is 4.7K, and I also confirm those abnormal values are all appearing both by the host and the analyzer at the same time, otherwise, I imitate the timing sequence which I catched by logic analyzer, implemented the base command and 0x44 command, in other words, the timing sequence I used should be ok, the bq40z50 is also ok since the data showed by the bqstudio is ok, so only the link maybe someting wrong?

    Waiting for your reply.

    Thanks

    Star

  • 0 in reply to Star Xu
    TI__Guru** 105590 points

    Hello Star,

    If the TI toolchain (BQStudio and EV2400) does not show the issue it is most likely a timing issue with the host. Yes something with the link may be causing the issue as well.

    Sincerely,

    Wyatt Keller