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TMS320C6748: Accessing higher memory location of NAND flash connected on CS3.

Shrikrishna B
Prodigy 180 points
Part Number: TMS320C6748

Hello,

On TMS320cC6748, 4GBits NAND is connected on CS3 which supports 32MBytes addressing capacity. So can anyone explain how to access NAND memory beyond 32MBytes, and how should be configuration in linker script.

  • 0
    TI__Guru 65405 points
    Hi Shrikrishna,

    I've forwarded this to the SW experts. Their feedback should be posted here.

    BR
    Tsvetolin Shulev
  • 0
    TI__Guru** 116170 points
    NAND memory addressing doesn't use the address lines so there isn't a limit to the size of NAND part that can be used to interface with EMIF16 (it is not limited by the memory mapped 32MB like NOR etc, which use address lines). The addressing is handled by the software driver that you develop.

    NAND memory is organized in form of blocks and pages so the page programming and read operations are accessed by providing the block and page numbers and not using direct addressing as in case of EMIF NOR interface. there is nothing that you can do in the linker command file so I would recommend that you look at a NAND Writer or driver code to see how this access operates.

    Regards,
    Rahul
  • 0 in reply to Rahul Prabhu
    Intellectual 280 points

    Hi Rahul,

    Thanks for your answer. It seems that the NANDWriter tool from the FlashAndBuildUtils package is using memory mapped access to  the external flash chip. Is it correct to conclude that it is possible to use both memory mapped and block/page based addressing? In case of memory mapped addressing, the accessible size is limited to 32MB.

    Since the native interface to the flash chip is block/page based, I assume that this is more efficient than the memory mapped solution?

    Kind regards,

    Timon Zijnge

  • 0 in reply to Timon Zijnge
    TI__Guru** 116170 points
    Timon,

    The NAND devices that we have on TI evaluation platforms have 2GB memory capacity and all of this can be accessed by the EMIF NAND driver code. USing EMIF interface you can use NOR flash devices that are direct memory mapped but for NAND, you need to follow the command and address protocol to access block/page data.

    In terms of speed, EMIF NOR Is faster than EMIF NAND interface as you can see from the BOOT data provided here:
    processors.wiki.ti.com/.../OMAP-L138_Boot_Benchmarks

    For checking how direct access memory is interfaced with this device check the wiki here:
    processors.wiki.ti.com/.../Connecting_NOR_Flash_to_OMAP-L138

    Hope this helps.

    Regards,
    Rahul