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DFF flag set

Mike_chute
Intellectual 825 points

Other Parts Discussed in Thread: BQ20Z90

In PFstatus we have several batteries with the DFF flag set. The pack doesn't shut off when the pack voltage is below the Shutdown voltage. The Z95 is still producing 3.1v

from pin 8 REG33. What can cause the DFF flag to be set?

  • 0
    TI__Guru 73830 points

    Mike

    The device will not enter Shutdown, if any permanent failure flags are set.

    This statement is from the TRM.

    "Data Flash Failure—The bq20z90/bq20z95 can detect if the data flash is not operating correctly. A
    permanent failure is reported when either: (i) After a full reset the instruction flash checksum does
    not verify; (ii) if any data flash write does not verify; or (iii) if any data flash erase does not verify."

    Was the pack voltage low when the DFF fault occurred?

    Regards
    Tom

  • 0 in reply to ThomasCosby
    Intellectual 825 points

    The device will not enter Shutdown, if any permanent failure flags are set.

    I am not sure when the DFF fault occured. The PF Status -Scanning has the DFF and RSVD set. So those will keep the 3.3v  at pin 8. That is a problem because I am powering a I2C expander from that voltage. Over time it will discharge my pack.  I need to know how to turn off the DFF flag. The reset permanent failure command didn't work. I can't see anything wrong with the gg file to produce a DFF fault.

    Mike

  • 0 in reply to Mike_chute
    TI__Guru 73830 points

    Mike

    If you cannot clear the DFF fault with the PF clear code, then there probably is a DFF fault. You will need to reload the senc file to fix the firmware. I attached the senc file, if you need it.

    Regards
    Tom

    bq20z95_1_50.senc
  • 0 in reply to ThomasCosby
    Intellectual 825 points

    That is bad because we could deplete the battery. If I reprogram the battery with the senc u sent will that erase the gg file and chemistry file? Will that cause the max error to be greater than 1%.

  • 0 in reply to Mike_chute
    TI__Guru 73830 points

    Mike

    If the DF is truly corrupted, then you do not want to operate the device in that condition either, because it may not work properly. You could reload the senc file and your golden DFI or ROM file and it should return to the state of a new pack. (MaxErr should be 1%.) If you want to extract senc files from a good pack and a bad pack and send them to me, then I will try to determine what is corrupted. Since you have several packs returned in this condition - the next step would to determine how the corruption is induced and find a way to prevent it.

    Regards
    Tom

  • 0 in reply to Mike_chute
    Intellectual 825 points

    I dont believe the zip file with the two senc files were sent to you. My email address is mulmer@stingermedical.com if you need to contact me directly.

    Mike

  • 0 in reply to Mike_chute
    Prodigy 130 points

    I thought I'd share some experience with DFF. On a 20Z45 pack, we encountered DFF because the system host issued a reset and immediately tried to access dataflash.  The reset was part of a host controlled learning cycle. We discovered that there needs to be at least 2S delay after a Reset, before accessing the Data Flash. Hope this helps