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BQ40Z50: -R3 battery communication data loss with system

Long Lu
Prodigy 60 points
Part Number: BQ40Z50

Tool/software:

Our customer found communication data loss during test and it happened frequently. System read battery information every 5s and there're about 37 error during 30min.

Also here attached both battery and system side schematic and oscilloscope capture when good and fail reading happend.

Is there any clue what might casue this issue? or shoud I include more information for analysis?

Thanks very much.

battery_side_bq40z50_schematic.pdf

  • 0
    TI__Mastermind 28480 points

    Hello,

    Does the host in use support clock stretching? If so, can you please confirm whether the FLASH_BUSY_WAIT bit in the SBS Configuration register is set at this time?

    Regards,

    Anthony

  • 0 in reply to Anthony
    Prodigy 60 points

    Hi Anthony,

    Thanks for the prompt response.

    The host is using Simulated I2C, there's no clock stretching related function, also FLASH_BUSY_WAIT bit is set to 0 by default in bq40z50-R3 fuel gauge.

  • 0 in reply to Long Lu
    TI__Mastermind 28480 points

    Hello,

    Understood, thank you for the clarification.

    In the commands that are creating errors, can you please confirm that the timing requirements are being met for the device?

    Regards,

    Anthony

  • 0 in reply to Anthony
    Prodigy 60 points

    Hi Anthony, there's the screenshot of the bad communication in the orignal post, is this helpful?

    Also our customer mentioned simulated I2C method with qualcomm SM6225, do you think it will have issues with the SMBus v1.1 compatible interface which is supported by bq40z50 chip?

    Thanks.

  • 0 in reply to Long Lu
    TI__Mastermind 28480 points

    Hello,

    It is difficult to confirm the exact values if we cannot zoom in and check the actual time values in the scope shot, however I believe this should be fine since there are previous commands being sent with this structure that are working. Is there a possibility that there are collisions on the communication lines that are causing this issue since it is being sent every 5 seconds?

    Regards,

    Anthony

  • 0 in reply to Anthony
    Prodigy 60 points

    Hi Anthony, our customer tried to remove all the other components only leaving battery on the communication line, these errors still exist, so it might not be collisions.

    Also, they send the error message and the oscilloscope screenshot of the bad communication

  • 0 in reply to Long Lu
    TI__Mastermind 28480 points

    Hi Long,

    The screenshot above seems like the gauge is using clock stretching seen below:

    Has this been tested yet with the FLASH_BUSY_WAIT bit enabled to see if it alleviates the issue?

    Regards.

    Anthony

  • 0 in reply to Anthony
    Prodigy 60 points

    Tried to change the communication frequency to 400KHz on both system and battery side (XL bit  in SBS Configuration), it seems like this problem disppeared.

    Thanks.