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BQ27427: SET_CFGUPDATE waiting time

Richard Allen
Prodigy 71 points
Part Number: BQ27427


Tool/software:

I'm looking at https://www.ti.com/lit/ug/sluucd5/sluucd5.pdf, JANUARY 2023, trying to work out the fastest way to adjust the chemistry configuration, and verify my understanding of the delays required in two different sections.

Section 4.2 Chemistry Profile Change Example, steps 3: "Send SET_CFGUPDATE subcommand, Control(0x0013).". Step 4: "Confirm CFGUPDATE mode by polling Flags() register until bit 4 is set. The host should wait for 1 second to ensure IT processing has been stopped."

Section 5.1.9 SET_CFGUPDATE: 0x0013 Instructs the fuel gauge to set the Flags() [CFGUPMODE] bit to 1 and enter CONFIG UPDATE mode. This command is only available when the fuel gauge is UNSEALED. After the command is sent, the host must wait a minimum of 1100ms to start modifying any parameters.

Does SET_CFGUPDATE need 1100ms before polling Flags() to confirm CFGUPDATE mode? Or is the 1100ms a safe way to wait for CFGUPDATE mode without polling Flags()?

Are there any delays in this sequence for section 4.2, steps 3+4 that could be safely removed?

  1. Send SET_CFGUPDATE subcommand, Control(0x0013).
  2. Wait 1100ms (from Section 5.1.9)
  3. Poll CFGUPDATE mode by polling Flags() register until bit 4 is set.
  4. Wait 1 second to ensure IT processing has been stopped.
  • 0
    TI__Mastermind 25441 points

    Hello, 

    I would recommend to follow the delay sequence outlined in the device Technical Reference Manual. 

    Regards, 

    Robert. 

  • 0 in reply to Jonny
    Prodigy 71 points

    The delay sequence in the TRM is ambiguous.

  • 0 in reply to Richard Allen
    TI__Mastermind 25441 points

    Hello Richard, 

    After sending the SET_CFGUPDATE subcommand you should wait 1100ms, this would be the average minimum time until the bit is set. the 1 second delay would be the time to wait to ensure the IT processing has been stopped. I recommend doing some tests on your end to confirm your timing is correct. 

    Regards, 

    Robert. 

  • 0 in reply to Jonny
    Prodigy 71 points

    Thank you for your help with this Robert,

    After sending the SET_CFGUPDATE subcommand, should I wait 1100ms before waiting until the bit is set?

    Or after sending SET_CFGUPDATE subcommand, wait until the bit is set. (and waiting for that bit to set may take around 1100ms)?


    > the 1 second delay would be the time to wait to ensure the IT processing has been stopped.

    For my curiosity, can you say what "IT processing" is or stands for? Is it possible to poll for processing/stopped?

    > I recommend doing some tests on your end to confirm your timing is correct. 

    Will do!

  • 0 in reply to Richard Allen
    TI__Mastermind 25441 points

    Hey Richard, 

    The IT processing is referring to the Impedance Track processing (the gauging algorithm) and is part of the normal operation of the gauge. 

    Regards, 

    Robert.