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BQ27421-G1A: load golden image in driver

Hank Chu
Expert 1340 points
Part Number: BQ27421-G1

We used TI BQ27421-G1A gauge in our product.

Currently, the golden image is only loaded into gauge when the battery had been disconnected.

1) After the plastic case of the product is put on the PCB Assembly, if the golden image is updated in F/W image,

it is necessary for the customer to disconnect the battery inside.

In order to reload the golden image into the gauge.

1-1) But this behavior is not REASONABLE and user-friendly.

2) If we reload the golden image into the gauge every time when gauge driver was initialized during the bot-up of system,

it will over-write the parameters in Data Memory of gauge every time when the system booted up.

2-1)  Are there any side-effect if we do so?

Thank you.

  • 0
    TI__Guru 61006 points
    2-1: This is not recommended because the gauge will lose impedance information for the installed battery every time you boot up.

    You can check the ITPOR bit in the flags register during system boot up. If this bit is set then the gauge was reset and you should download the .gm.fs file.
  • 0 in reply to Dominik Hartl11
    Expert 1340 points
    Thank you very much.

    1) We met the problem as follows:
    >> The new golden image is in the new F/W image.
    >> And after the new F/W image is upgraded into the device with the plastic case,
    >> the customer cannot disconnect the battery (in the plastic case) to let gauge driver reload the new golden image into gauge.
    >> Because the plastic case is already put on the PCB Assembly, it cannot disconnect the battery to do so.

    Q2) Will the gauge re-learn the impedance information for the installed battery every time the gauge driver boots up and reloads the golden image?

    3) According to the bq27421-G1 Technical Reference (document: SLUUAC5C), Chapter 4.4 Flags(): 0x06 and 0x07, it said:
    >> ITPOR = Indicates a POR or RESET subcommand has occurred.

    3-1) The current gauge driver already only loaded the golden image if ITPOR bit is set.

    3-2) It is not same as the problem we met (F/W upgraded with new golden image).
    Q3-2-1) Could you tell us your comment for the problem in 1)?

    Have a nice day.
  • 0 in reply to Hank Chu
    TI__Guru 61006 points
    A2: The gauge will start with the battery data from the golden image. The gauge will re-learn over time (several charge/discharge cycles) until you load the golden image again.

    There is no need to physically disconnect the battery when you update anything.

    If you have a new FW with a new golden image (which is intended to update the gauge with a better configuration) then you'll have to download the new golde image once and the gauge will start "fresh" with this new golden image. It will re-learn the characteristics of your cell over time.
  • 0 in reply to Dominik Hartl11
    Expert 1340 points
    Thank you for your kind support.
    We got it.

    Because it is possible to upgrade a new F/W with a new golden image in the future,
    we will reload the golden image every time the system boots up.
    In order to make sure the new golden image is loaded into the gauge.