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bq34z100 Control Sub Commands

Steve Hinshaw
Intellectual 515 points
Other Parts Discussed in Thread: MSP430F5638, BQ34Z100

I'm writing firmware for a MSP430F5638 to read the bq34z100 fuel gauge using I2C and have the standard and extended commands working, but have a few questions about reading the control sub command information.

I have a routine to read the control sub command information and the values that I get back match the values read using the DataRam -> Conrol method of reading the control values with the exception of reading the Static Chem Checksum. Is a delay required between issuing the Static Chem Checksum command and reading the result?

I've noticed that the values that I read for the Device Type, FW Ver and HW Ver with either my code or the TI app using either the DataRam -> Conrol method or the Read/Write I2C Byte methods don't match the FW Ver or HW Ver info on the Data Flash tab, should this not be the same?

Thanks,
Steve

  • 0
    TI__Guru 73830 points

    Steve,

    A wait time is required after issuing the Checksum commands and reading the result. It should be about 100ms.


    The FW_VERSION and HW_VERSION reported by the Control Subcommand reports the actual revisions of the device. The DF parameters are available to the user to set the firmware and hardware versions on the pack.

    Tom

  • 0 in reply to ThomasCosby
    Intellectual 515 points

    Hi Tom,

    Thanks for the quick reply!

    One more question-

    A footnote to the Extended Commands table on page 35 of the datasheet states "In SEALED mode, data flash cannot be accessed through commands 0x3e and 0x3f." How can you read the 'Cell Charge Voltage T-T', 'Charge Current T-T' and 'JEITA T' parameters located at offsets 28-40 of subclass 48 when the pack is sealed? I would think that the charger would need access to these parameters for setting the charging profile for the battery pack.

    Thanks,

    Steve

  • 0 in reply to Steve Hinshaw
    TI__Guru 73830 points

    Steve, 

    Data flash accesses are restricted when sealed. The charging profile is normally set up when the pack is built and then not changed. The gauge will then broadcast the ChargingCurrent and ChargingVoltage to the charger. But, you can unseal it and change the profile. 

    Tom

  • 0 in reply to ThomasCosby
    Intellectual 515 points

    Tom,

    The charging parameters for the charger that I'm using are set from the same MSP430F5638 that I'm using to read the battery info, so my question is, how does the 'charger' read this information when the battery is sealed? Do the can'd chargers that directly read the charging requirements from the fuel gauge unseal the pack to read the charging parameters and then re-seal the pack?


    Thanks,

    Steve

  • 0 in reply to Steve Hinshaw
    TI__Guru 73830 points

    I forgot that the bq34z devices do not have broadcast mode. You can read the ChargingVoltage with extended command 30/31 and the ChargingCurrent with 32/33 when the pack is sealed.

  • 0 in reply to ThomasCosby
    Intellectual 515 points

    Tom,

    OK, but why can you program JEITA charging profile info into the bq34Z100 if the charger can't read this info from a sealed battery???


    Steve