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Original question:

BQ76942: Programming BQ76942

BQ76942: Programming a custom board using EVM

Steven Hunter
Intellectual 420 points
Part Number: BQ76942
Other Parts Discussed in Thread: BQSTUDIO, EV2400

I am having trouble writing the OTP memory on a custom board using the EVM. I jumper over the CLK, SDA, and ground. I can communicate fine until I "Write All" to the target. Then I lose communication.

Is this because the 12V necessary for the OTP programming is way below the Shutdown voltage setting?

Also, the OTPB bit is high indicating that conditions are not met for programming despite the voltage showing 12.0v and the temperature is 23C. 

Deepcore Battery Settings-9.gg.csv

  • 0
    TI__Mastermind 42060 points

    Hello Steven,

    Are you applying power to both BAT and VC16? These both require a voltage to be able to OTP the device. What pull-ups are you using in the SDA/CLK lines? Make sure the connection wires are as short as possible. If using bqStudio, make sure that "Auto Refresh" is OFF.

    It is possible that the device enters SHUTDOWN if you have a setting that causes a SHUTDOWN due to low voltage. The following FAQ may answer some of the OTP questions:

    Maybe try lowering the voltage to slightly below 12-V. 11-V should work fine. The device must also be in FULLACCESS. 

    Best Regards,

    Luis Hernandez Salomon

  • 0
    Intellectual 420 points

    BAT is one diode drop below VC16. We are basically using the reference design for stand alone operation.

    The SDA and CLK signals look sharp on a scope.

    I don't see an "Auto Refresh" setting. Scan mode is off.

    I don't see where to set FULLACCESS.

  • 0 in reply to Steven Hunter
    TI__Mastermind 42060 points

    Hello Steven,

    Here is an image of the "Auto Refresh":

    You can see if you are in FULLACCESS by reading the Battery Status[SEC1–SEC0] bits:

    Also, ensure that you have the latest EV2400 firmware installed, this should be version v0.32.

    Best Regards,

    Luis Hernandez Salomon