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TMS570 "Extended" Reset Reason: Recommended method to pass Information through a software-initiated system reset

Martin Momberg
Prodigy 125 points

What is the recommended method to pass additional Information (one or two 32-bit words) from a Software initiating a System reset (Setting SYSECR) to the boot routine?

Motivation: When initiating a reset from Software, the Software needs to differentiate between a normal "Warm Start" and a "Reset to Software Loader". The reset routine has to decide between the normal Software Image and the loader image, so I have to pass Information between the resetting function and the boot routine.

With best regards

Martin

  • 0
    TI__Guru**** 183806 points
    Hi Martin,
    One idea is that before generating a software reset by writing to the SYSECR you will first write a key value to the RAM. You will use this key to differentiate between a normal "Warm Start" vs a "Reset to Software Loader". The content of the RAM is maintained after a warm reset. One more recommendation is that after you write the key to the RAM, you will first read back the key to make sure the key is truly written to the RAM. This is just to avoid any race condition between writing to the RAM and writing to the SYSECR.
  • 0 in reply to Charles Tsai
    Prodigy 125 points
    Hi Charles,

    thank you for your answer.
    I was hoping for something different than using the RAM, as with the TMS570 RAM read access may lead to exceptions when not initialized.
    But if you don't see a dedicated register in the TMS570 that could be used for that purpose, I will try it with the RAM.

    With best regards
    Martin
  • 0 in reply to Martin Momberg
    TI__Guru**** 183806 points
    Hi Martin,
    The reason is that pretty much all the registers will get reset after you issue a system reset via the SYSECR.
  • 0 in reply to Charles Tsai
    Prodigy 125 points
    Hi Charles,

    thank you for your answers.

    I will go the RAM path.

    With best regards

    Martin
  • 0 in reply to Charles Tsai
    Prodigy 60 points
    Hi Charles, I am wondering will there be any flag indicating TMS570 is reset from an exception instead a normal software reset via the SYSECR? I am trying to do the same thing as Martin did.