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BQ40Z50-R1: Static Chem DF Signature on a sealed battery

Jerry%20Leung
Intellectual 905 points
Part Number: BQ40Z50-R1

Hi, 

I am working with a client who is using the BQ40Z50-R1 and would like to get some clarifications for the following:

"We’re trying to verify that the BQ40Z50-R1 based battery pack has been programmed correctly.  It looks like the field we want to check is the “Static Chem DF Signature.”  Please verify this.  The challenge seems to be that on the BQ-Studio tool no parameters can be read on a sealed battery.  Is this a tool feature, or a BQ40Z50-R1 feature?  In other words, can we verify that a pack has been programmed correctly after it’s been sealed, and if so how?  We’d like to do this quick check as part of the power-up-self-test."

Thanks in advance for the help,

Jerry

  • 0
    TI__Mastermind 42535 points
    You cannot verify a pack after it has been sealed. If you want to read the statis chem df checksum, you can do it via the mac command 0x0008. But you cannot write df parameters after sealing the gauge. This is not a feature of the tool but it is how the bq40z50-r1 gauge works.
  • 0 in reply to Batt
    TI__Intellectual 905 points
    Hi Batt,

    Thanks for the response. Is there a recommended document that describes what a MAC command is? The customer mentioned that the TRM has lots of info, but almost no explanation.

    We’re looking for a check value that covers the whole set of customer-set parameters – i.e. a check to see if the pack was programed with our rev x.x file vs. not programmed vs. programmed with different parameters. Please verify that “Static DF Signature” is the checksum that does this.

    Thanks for the help and best regards,
    Jerry
  • 0 in reply to Jerry%20Leung
    TI__Guru* 76230 points

    Jerry,

    Yes The static df signature can be used for verification of static programmed parameters (one that don't) get updated. Alternative, they could do a comparison of the file they programmed with one extracted after the programming has been done. The TRM contains thorough description of what the mac commands are and how they can be sent. For additional info, you can see the smbus spec document attached.

    4657.smbus20[1].pdf

    thanks

    Onyx

  • 0 in reply to Onyx Ahiakwo
    TI__Intellectual 905 points
    Hi Onyx,

    Want to clarify a couple questions from the customer:
    The big question is can the below be done on a sealed battery? It seems like TI built in several verification mechanisms, but none that work on a sealed battery. On a sealed battery, this forces us to include unsealing, verifying, and resealing FW capability, which can be very dangerous in a product. A product should not have the ability to change the battery parameters, unless it’s a sophisticated application that is required to do so. Please confirm.

    Another follow-up question on this. Why is the Static DF Signature (and the All DF Signature) always 0 on BQ Studio? The Static Chem DF Signature is displayed as a number so it looks to be supported, but this only covers the chem parameters (which are important for safety, but doesn’t tell us which parameter file is loaded).

    Thanks for info and support.
    Best,
    Jerry
  • 0 in reply to Jerry%20Leung
    TI__Guru* 76230 points
    Most folks are out for the July 4th Holidays. We should get back to you after the break.
  • 0 in reply to Onyx Ahiakwo
    TI__Guru* 76230 points
    When a device is sealed only limited registers are accessible. The parameters that are not accessible are made that way to protect the customers data flash settings from third parties. Your host isn't supposed to do any unsealing as the pertinent data needed are available even in the sealed state.

    Static df is of no consequence and isn't functional. static chem df is functional and helps guarantee the integrity of the chem id data

    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    TI__Genius 14985 points

    The checksum commands are available when in SEALED mode.  In the bq40z5-R1 TRM, Table 13-1 lists the MAC commands available and the 7th column denotes whether those commands are allowed while in SEALED mode or not. 

    The StaticDFSignature, StaticChemDFSignature, and possibly AllDFSignature are the commands you sound interested in using.