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TMS320F28386D: DAC offset trimming from OTP

Clément Letonnelier
Expert 2426 points
Part Number: TMS320F28386D
Other Parts Discussed in Thread: C2000WARE

Hello,

We are using the ADC VREFHI/VREFLO as reference voltages for the DAC and we therefore must run the DAC offset adjustment unless I am mistaken.

The TRM states:

Use the function call DAC_tuneOffsetTrim() found in C2000Ware to adjust the offset.

I looked at the code and the code is based on a read of the current value of the register which is problematic if the call to the calibration function is performed multiple times.

Is there a way to base the calibration on a value that would be readable from OTP similarly to the ADC ?

Best regards,

C. Letonnelier

  • +1
    TI__Mastermind 28275 points

    Hi Clement,

    The DAC_tuneOffsetTrim() is only meant to be called once at the start of your application since in a typical application, the reference voltage is fixed. The difference between this and the ADC is that the ADC function is loading completely different trims based on mode while DAC_tuneOffsetTrim() is adjusting the existing trim.

  • 0 in reply to Frank Ankapong
    Expert 2426 points

    Hi,

    I agree with you but that doesn't answer my question.

    Are the initial offsets stored somewhere in OTP where we could read the value and base the calibration correction from there ?

    Best regards,

    Clément

  • 0 in reply to Clément Letonnelier
    TI__Mastermind 28275 points

    Clement,

    Yes, the values are stored in OTP and automatically loaded by the bootrom but we don't provide the locations since it is not needed. However, you can always copy the original values from the GPDAC offset register before running the DAC_tuneOffsetTrim() and store it in any variable of your choice. Every time device boots after reset, bootrom will copy over the original value.