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cant find bq78PL114 EVM on SMBUS

Ronald Deang
Intellectual 260 points
Other Parts Discussed in Thread: BQ78PL114, BQWIZARD

Hi, I'm working on configuring a 6 cell battery circuit on a bq78PL114 EVM. Right now I'm just simulating the battery cells with resistors as shown in the user's guide. However, when I try to run bqWizard, it can't find the bq78PL114 on the SMBUS line. I'm using the usb-to-gpio adapter and I've updated its firmware. Can anyone help me figure out why the SMBUS connection isn't working?

 

I'm concerned the board isn't being powered correctly and that's causing the SMBUS to fail. I know there are LEDs, but when I turn on the power supply I don't see anything happen with them. Is this just because I'm using resistors and not actual battery cells? How can I check that the board is actually running?

 

Thanks,

Ronald Deang

  • 0
    TI__Intellectual 1940 points

    The bq78PL114 expects 8 cells.  If you don't have 8, you will initially get 0 cells found.  Check section 5.7 of the user guide.  It discusses switching the cell count.

    You will eventually need to change the firmware too.  See the attached initial evaluation and firmware upgrade procedure.

     

    bq78PL114S12 Procedure.doc
  • 0 in reply to Jim M15252
    Intellectual 260 points

    I read through section 5.7 and I'm not able to get to the configuration menu. When I run the BQWizard, it doesn't go past the splash screen telling me "Unable to connect to device Please Check power and the connections to the hardware." I'm presented three options: Scan Bus, Retry and Exit. Selecting Scan Bus checks all the adresses and then gives me "No target found on SMBus!" Retry gives me "Unable to connect to device..." I'm running ver 3.0.16

    Could the SMBus be down because I'm underpowering the board? I know we need 3.6 V/cell, which I was not providing (only because I couldn't find a power supply that large). However, I just found a 24V power supply and will be giving that a try. But could that be the issue?

    Thanks,

    Ronald

  • 0 in reply to Ronald Deang
    TI__Intellectual 1940 points

    Verify all cell voltages are steadily providing 3.6V.

    Verify that the VLDO1 (ref to VSS) and VLDO2 (ref to V2) of the bq78PL114 are reading 2.5V.

    Verify that there is digital communications on the SDO0 pin.  Just look that there is activity, do not try to decode it as the protocol is proprietary.

  • 0 in reply to Jim M15252
    Intellectual 260 points

    Great, it worked! Thanks! Turns out I wasn't getting the right voltage across the resistors.

    I do have one more question though. In section 5.7 of the user manual, to turn on the FETs, it talks about the Pack Configuration tab and editing the Algorithm Enable register. I can't find this in the software. I think it may have changed since version 2.5 as referenced in the document. Do you know how I can change this setting?

     

    edit: Never mind. I found the tab; it was hidden and I had to click on the Tab button in the upper right-hand corner. Thanks again.