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F28M35 - Shared RAM initialization for External Boot

Bas van de Ven
Prodigy 140 points

Hello,

For our application we'd like to use an external device to boot the F28M35 via SSI0. Therefore, it would be ideal if the uploaded binary contains the C28 code in shared RAM, so the M3 user application can simply boot the C28 by giving it write/execute access to SxRAM and then start it from there. However, I've read the documentation about RAM initialization and I'm not sure whether this approach will work.

If the C28 code is written as data in shared RAM during the M3's boot sequence will the parity then be correct once the bootloader finishes? Because using the RAM init functionality is not possible during during bootloading, and using MSxRTESTINIT1 in the M3 user application after uploading (which zero initializes all memory) beats the purpose of having it in shared RAM to begin with.

Regards,


Bas

  • 0
    TI__Guru** 116581 points

    Hi,

    In F28M35 devices, ECC/parity get's calculated in HW and gets updated along with the data. As long as the SxRAM, used in this case, get initialized using RAM INIT , before downloading the code into it, it'll work fine.

    Let us know if you have further query on this.

    Regards,

    Vivek Singh  

  • 0 in reply to Vivek Singh
    Prodigy 140 points

    Hi Vivek,

    Thanks for the fast response, but from what I understand the RAM_INIT functionality can only be called from user (application) code which would too late, as the intention is to write the SxRAM once during the bootload procedure of the M3.

    If I use the M3 bootloader to write all memory of the C28's code/data in uninitialized Shared RAM, then the parity will be right afterward and no faults will be generated?

    Regards,

    Bas

  • 0 in reply to Bas van de Ven
    TI__Guru** 116581 points

    Hi Bas,

    Shared RAMs are initialized using RAMINIT during device boot up time (by BOOT ROM Code). So after M3 bootloader writes to these memories for C28x, parity will be correct and there should not cause any error afterwords.

    Regards,

    Vivek Singh

  • 0 in reply to Vivek Singh
    Prodigy 140 points

    Hello Vivek,

    Ok, I see. Thanks you for the clarification.

    Regards,

    Bas