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Original question:

BQ40Z80EVM-020: Can't connect through Battery Management studio or Python scripts

BQ40Z80: Chip unresponsive after calibration with BQstudio

shane mattner
Prodigy 90 points
Part Number: BQ40Z80
Other Parts Discussed in Thread: BQSTUDIO, EV2400,

Tool/software:

I made a custom board with BQ40Z80RSMT on it.  I'm using a 3s configuration.

I was able to communicate with the chip with the EV2400 and BQstudio.  This appeared to work fine, I was able to read and write parameters.  Then I tried to do a calibration, where I only input the cell 1 voltage (there were 4 different fields).  

The calibration went through successfully and now I cannot talk to the chip at all.  Here is the schematic:

I tried removing all the batteries and power and re-connecting but I had no luck re-connecting.  Any ideas what might have happened?

  • 0
    Prodigy 90 points

    I also tested with a ESP32 application that had been previously able to communicate with the chip. After the calibration I was not able to talk to the chip.

  • 0 in reply to shane mattner
    TI__Guru 61366 points

    Please make sure that there's a voltage on PACK. It looks like you may have configured something to trip the protector and the gauge turns off everything. If the gauge is in shutdown it won't communicate. You can try connecting PACK to the battery voltage temporarily (not permanently, you don't want to disable the protection) and see if this makes it possible to talk to the gauge again.

  • 0 in reply to Dominik Hartl11
    Prodigy 90 points

     thank you for the suggestion.  I do not have anything attached to the Pack output, I just have the batteries inserted (3s).  I tried removing all the batteries and inserting them 1 by 1 and still found the chip unresponsive.

    Is there any guide on how to do the calibration steps properly?  The BQstudio isn't easy to navigate with all the options.

  • 0 in reply to shane mattner
    TI__Guru 61366 points

    Are you able to recover communication with bqStudio? If not, then you may have triggered a state that requires re-flashing of the FW (due to a temporary voltage spike on a TS input).

  • 0 in reply to Dominik Hartl11
    Prodigy 90 points

    After momentarily touching BATT+ to PACK+ I was able to recover communications to the chip.  Thank you!

    Is there a document or guide I can follow for properly setting up the BQ40Z80 chip?

  • 0 in reply to shane mattner
    TI__Guru 61366 points

    This indicates that the gauge entered shutdown mode or was power cycled. Which is good as this indicates that this is not a major problem.

    The bq40z80 requires that you turn it on if it's e.g. in shutdown mode. It's intended to be permanently attached to cells in a battery so if you remove cells and re-connect them you need to restart the bq40z80 and one requirement is that the voltage on PACK exceeds 2.25V (see datasheet, 7.3).

    The EVM user's guide has information how to get started with this gauge: www.ti.com/.../sluubt4b.pdf