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TMS320F280039C: DCC tolerance

Ben Qin
Intellectual 2690 points

Part Number: TMS320F280039C

Hi Team,

There's an issue from the customer need your help:

In the DCC module, I don't understand the meaning of Tolerance? There are mainly two types of Tolerance in this module: as shown in the figure below.

The first one: Tolerance

The second one: Allowable Frequency Tolerance

I would like to ask how these two Tolerance are set? Is it inherent in the program or set by yourself? If you set it yourself, how should you set it up?

Could you help check this case?

Thanks & Regards,

Ben

  • 0
    TI__Genius 11081 points

    Hello Ben,

    The first number, "Tolerance", is essentially the measurement precision of the DCC. So, a tolerance of 0.1% means that the DCC is able to detect frequency changes to within 0.1% of the nominal frequency - if I'm checking PLL output at 120MHz, then a minimum drift of 120kHz will be detectable.

    The second number, "Allowable Frequency Tolerance", is the amount of error in the clock under measurement that can be permitted before an error condition occurs. This is determined by your system/application requirements. For instance, if a communications interface allows up to 1% of drift before it loses sync, then 1% is your allowable frequency tolerance.

    The easiest way to use these numbers is to use the DCC_continuousMonitor() driverlib function. You simply pass the parameters to this function, and it computes the corresponding counter values and writes them into the DCC registers for you.

    Best regards,
    Ibukun