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TMS320F28069: Abnormal Latency of Interrupt

Joyce Gao
Intellectual 2900 points
Part Number: TMS320F28069

Tool/software:

Hi expert,

When customer using F28069 for 20kHz switching frequency interrupt (50us), the main ISR task typically takes ~33us for running.

The issue we met now is:

We added the key/passcode for protection, under this circumstance, if adding 1 sub functions (such as if-else, but the if-else will not be jumped in to operate) or 1 calculation function (1 multiply code) in the main ISR, the time will take much longer than 50us (20us longer than before) and leads to abnormal performance.

Debugging Info:

  • If delete the key/passcode and do not use the key/passcode protection, this issue will be gone.
  • If shorten the ISR code, the issue will be gone.
  • If using emulator (xds100V2), the issue won't happen.

Now we still need the key/passcode be added, and adding a multiply calculation in the ISR, but could not reach the function. And it's very weird to be related to the passcode. We need to know the root cause and solution, please help check internally if any directions.

Thanks!

Joyce

  • 0
    TI__Mastermind 19305 points

    Hi Joyce,

    Are they able to share the key/passcode lines that were added and caused the increased execution time? It would also be helpful for me to see a screenshot of the disassembly generated for these lines (View -> Disassembly) to see if the code generated by the compiler looks to be inefficient/defective. A few additional questions:

    1. Do they have compiler optimizations turned on?
    2. Have they implemented interrupt nesting?
    3. Are they using any non-inline function calls inside the ISR? This usually isn't recommended.

    Best Regards,

    Delaney