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BQ27200 not talking nice on I2C bus - actually not talking at all...

DJH
Intellectual 985 points
Other Parts Discussed in Thread: BQ27200

I am looking for some pointers as what I can check to figure out why my BQ27200 isn't responding to I2C calls.  I don't get any ack after calling it.  I've tried address 0x55, 0x77, 0xAA, 0xAB, plus several others.  In fact, I've actually had a linux utility go off and query every possible address and I get responses back from my other three devices - just nothing from the mute in the corner.

The part is powered up and all the pins seem to be at acceptable levels.  Is there any way I can tell if the part is alive besides I2C?  Does anyone have any ideas on what else I can investigate; at what point do I start to think it's a dead chip?

Thanks in advance,

-David

  • 0
    TI__Expert 4115 points

    David,

    Can you provide some more information the issue?  The following information would be very beneficial:

    • Are you using an EVM provided by TI or is this issue seen on a board that you have created?  If you have created a board can you provide the schematic and layout?
    • Have you been able to test out multiple ICs?  If so, do you see the same issue on each?
    • Could you provide oscope shots that show the I2C bus communication? 

    Thank you.

  • 0 in reply to Jared Casey
    Intellectual 985 points

    1.  This testing is being done on a custom board.  Here is the schematic:

    5481.BQ27200.pdf

    2.  Not yet, but that is in process.  I am having it replaced right now.

    3.  Yes.  Here are scope images of writes to 4 different addresses.  0x55, 0x77, 0xAA, 0xAB:

  • 0 in reply to DJH
    TI__Expert 4115 points

    David,

    Sorry about the delay.  The factory is looking into the issue.  Did you see the issue when the IC was swapped out?  Any other updates?  Thank you.

  • 0 in reply to Jared Casey
    Intellectual 985 points

    Yes, the problem persisted even after swapping out the chip.  Every pin was behaving correctly and the levels were all within spec, I just hadn't seen any response on the I2C.  On a lark, one of the software engineers mentioned if I'd tried a slower data rate.  I said that I had...I thought.  Turns out that if I turn the data rate down to 100KHz then I get responses from the chip.

    I haven't looked carefully since finding that out, but I don't recall reading that in the datasheet.  400KHz is such a standard that I'm surprised I had to go to 100KHz.  But anyway, at least we can yell at it and it yells something back. 

    Thanks for your support.

    -David