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TMS320F28022: Question about errata : ADC: ADC Result Conversion When Sampling Ends on 14th Cycle of Previous Conversion, ACQPS = 6 or 7

Shinji Ueda
Expert 5440 points
Part Number: TMS320F28022


Hi champs,

I have a question about errata : ADC: ADC Result Conversion When Sampling Ends on 14th Cycle of Previous Conversion, ACQPS = 6 or 7

This errata does not write that a problem occurs on a specific channel.

in my understanding, this problem occurs only with timing. Is it correct?

If it occurs depend on timing and channel, please let me know.

Regards,

Shinji Ueda

  • 0
    TI__Guru* 81440 points

    Ueda-san,

    Yes, you are correct this only has a timing dependence, there is no ADCIN or SOCx dependence on the errata.

    Best regards,

    Matthew

  • 0 in reply to MatthewPate
    TI__Expert 5440 points
    Matt--san,

    Thank you for your support and sorry for my rush.
    I have a one more question.

    When it set ACQPS=6 cycles, it does not seem to be a total of 14 cycles.
    ACQPS=6 : 6+6+1=13
    ACQPS=7 : 6+7+1=14
    Is this correct? What should I think about this?
    Please let me know.


    Regards,
    Shinji Ueda
  • 0 in reply to Shinji Ueda
    TI__Guru* 81440 points
    Ueda-san,
    Your math is correct, however, there is a boundary condition for the setting of ACQPS=6.

    If we are in continuous conversion(that is the next ADC trigger comes well before the current ADC conversion is complete) then there will be no issue, since the conversion will not complete on the 14th cycle.

    This is also true if the ADC is starting from full idle, since the math will always hold to 13.

    However, if the triggers come independently and/or are asynchronous to one another, there is a possibility that the conversion will begin not at t=0, but at t=1, which will cause the conversion to end on the 14th cycle and cause the errata condition to be met. So, ACQPS = 6 can be used, but a careful analysis of the other ADC triggers will need to be understood.

    Best,
    Matthew