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SARAM31 in C5532 for secondary Bootloader

Max Forster
Intellectual 485 points

Hi everybody,

I would like to implement a secondary bootloader (copy image from spi-flash to RAM and branch to main application) on C553x processor. We will need that in our project to be able to in-field program our device. So the execution steps would be 1) start internal bootloader 2) internal bootloader copy secondary bootloader from spi-flash to RAM and execute it 3) sec. bootloader copy image from somewhere else in spi-flash memory or save new image to spi-flash (e.g. via RS232)

Now my question is, may I use the SARAM 31 block for secondary bootloader application? As far as I understand Application Note SPRABL7A - "Using the TMS3205535/34/33/32 Bootloader" these block is used on all devices for internal bootloader and free to use after internal bootloader branch to application. But as I would like to use the C5532, in my project, I have also the information of the datasheet that these block (SARAM31) can not be used/accesed (=reserved).

Best regards,

Max

  • 0
    Expert 2615 points

    Can you please give the link for the documentation which says SARAM31 cannot be accessed on C5532?

    Usually on C55x family processors, SARAM31 is used by ROM bootloader so you cannot use this block for secondary bootloader. You may use it for dynamic memory allocations after your secondary bootloader starts execution. Usage of SARAM31 in secondary bootloader should not result in ROM bootloader loading some data during initial bootup.

    Since your program is divided in to two parts. You can allocate SARAM31 to the second part which will be loaded to memory by your secondary bootloader. Your first part of the program shall be small and may not need to use whole memory, I assume.

    - Pratap

  • 0 in reply to Pratap Reddy M V
    TI__Mastermind 23785 points

    That's is correct. C5532 does not support any on-chip SARAM. You have to choose either C5533/34/35 according to the amount of SARAM you need. There is a table 2-1 in the data manual, SPRS737 which shows the differences of on-chip SARAM supported on each devices.

    Hope this help.

    Regards.

  • 0 in reply to Steve Tsang
    Intellectual 485 points

    Hi everybody,

    thanks for the fast reply!

    @ Pratap: There is no documentation which says that you can not access SARAM31, but in official datasheet (SPRS737B) the C5532 is marked with 0kB of SARAM and also in memoy map the SARAM31 block is marked as "Reserved" memory area. Actually I am a little bit suprised about that too, as the C5532 uses also the internal ROM bootloader and therefore needs access to SARAM31 to work.

    However, you are right even if I can access the SARAM31 I can not use it for my secondary bootloader (only for data after boot process of first bootloader), as it will used from (first) ROM bootloader. I missed that in my refelections.

    Thanks for all your help!

    Max