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[TMS320C6678] Unwanted writting of multiple registers while writting the two last MPPA registers of L1 or L2 MPU

Vincent Meunier
Prodigy 20 points
Other Parts Discussed in Thread: TMS320C6678

Hello,

I'm currently developing an application on the TMS320C6678 using ASM and CCS6.1.1 and I have a question about MPU registers of L1P, L1D or L2 memory.

I want to give different levels of  access for those memory so I use the MPPA registers dedicated to each memory to give supervisor/user rights. (Cf "C66xx CorePac User Guide").

All the register are written normally but when I store value in MPPA registers for the two last pages (L1PMPPA30 and L1PMPPA31 for the L1P memory), there is many other registers written at the same time.

I would like to know if this is a normal behavior or if it is caused by a issue in my code?

Thank you for your help,

Best Regards,

Vincent

  • 0
    TI__Guru* 81335 points

    Welcome to the TI E2E forum. I hope you will find many good answers here and in the TI.com documents and in the TI Wiki Pages (for processor issues). Be sure to search those for helpful information and to browse for the questions others may have asked on similar topics (e2e.ti.com). Please read all the links below my signature.

    We will get back to you on the above query shortly. Thank you for your patience.

    Note: We strongly recommend you to create new e2e thread for your queries instead of following up on an old/closed e2e thread, new threads gets more attention than old threads and can provide link of old threads or information on the new post for clarity and faster response.

  • 0
    TI__Guru* 81335 points
    Vincent,

    1. Have you tried writing those registers from CCS memory window? Is it affecting other registers?
    2. Is it affecting the expected output of your program?

    Thank you.
  • 0 in reply to Raja
    Prodigy 20 points
    Hi Raja,

    I tried to write those register from the CCS memory Windows and it gave me the same result, every other register are written with it.
    I don't know if it is affecting the output of the program yet. But as it is a critical application I don't want to have unwanted behavior later.

    BR,

    Vincent
  • 0 in reply to Vincent Meunier
    TI__Genius 12805 points
    Hi Vincent

    I may be wrong here, but I am not sure that 6678 uses all 32 MPPA registers. Let's see what happens when you try to manipulate register 15 and register 16 (starting from 0) and compare it to the behavior of register 30 and 31.

    In general, when you change one register and some other register is changed it points out for some link between the two registers.

    Get back to me with the results of your experiments (change MPPA 15 and 16)

    Regards

    Ran