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TMS320F28335: Any RAM or peripheral memory not cleared by external reset?

Marty Shank
Intellectual 2100 points
Part Number: TMS320F28335

Quick question:

On the F28335, is there any RAM or peripheral memory location that I can write data to that won’t get cleared by an external reset.

 

  • 0
    TI__Genius 17315 points
    Marty,

    The memory does not get cleared with an external hardware reset. The only exception that I know of is with the F28x7x where RAMM0 (and possibly RAMM1 too) where this block is cleared. So what is the advantage of the F28x7x clearing memory during a "hardware" reset (not a software reset - i.e. CCS issued CPU reset)? This ensures that after the reset the original program code and data values will be in a known good state to provide a "safer" operation. For more details see lab 5 in the following workshop:

    processors.wiki.ti.com/.../C2000_Multi-Day_Workshop

    I hope this helps. If this answers your question, please click the green "Verified Answer" button. Thanks.

    - Ken
  • 0 in reply to Ken Schachter
    TI__Genius 17315 points
    Marty,

    Just a quick update, on F28x7x all the RAMs get cleared on an external reset. This is not the case for the F28335 or any of our other devices, as I mentioned in my previous post. For all of our devices, the only catch is by design this is not "guaranteed" and therefore there is very far remote possibility that memory content may get corrupted on an external reset. This possibility is extremely low and we have never experienced this issue.

    I hope this helps. If this answers your question, please click the green "Verified Answer" button. Thanks.

    - Ken
  • 0 in reply to Ken Schachter
    Prodigy 20 points

    Ken,

    If there is an external reset or a watchdog reset, doesn't the RAM get cleared in the init routine before jumping to main()?

    Jeff 

  • 0 in reply to Jeff Pankau
    TI__Genius 17315 points
    Jeff,

    Again, this is specific to the F28x7x, the RAMs get cleared by the boot ROM (InitBoot) after a reset. See chapter 3 in the F2807x / F2837xS / F2837xD TRMs for the device boot flow. For the other C2000 devices, the RAMs are not cleared by a reset or watchdog reset. To prove this, try the Lab 5 watchdog reset exercise in the C2000 Workshops:

    processors.wiki.ti.com/.../C2000_32-bit_Real-Time_MCU_Training

    I hope this helps. If this answers your question, please click the green "Verified Answer" button. Thanks.

    - Ken