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c6678 memory map question

woodyiy
Intellectual 310 points

Other Parts Discussed in Thread: TMS320C6678

Hello,everyone, i am using the dsp tms320c6678, but one thing makes me confused. The tms320c6678 data manual shows us the memory map address in table 2-2 on page 19-25, and the table says that the data space of EMIF16CS2  is from 0x70000000-0x73ffffff,this means that it needs 26 address pins, but the dsp has only 24 adress pins.can anyone tell me how to explain this problem? Thanks !

  • 0
    Mastermind 6670 points

    Hi,

    The datasheet reports the are reserved in the DSP memory map for each CS, that is the maximum you can address. The effective addresable space depend on the kind of memory you connect. See the note (1) of the datasheet memory map table:

    (1) 32MB per chip select for 16-bit NOR and SRAM. 16MB per chip select for 8-bit NOR and SRAM. More than 32MB allowed by NAND flash

    So, 24 pins for 16 bits memory = 16MB x 2 = 32MBytes maximum for SRAM and NOR.

    In case of NAND the Data bus is used for the command and address.

  • 0 in reply to Alberto Chessa
    Mastermind 6240 points

    Hi,

    The maximum is 32 MB, but the highest address that you try to access is the last one 0x73FFFFFE. If you try to write something to the position 0x70000002, the value of the 24-bit address bus will actually be 0x000001 instead of 0x2 (due to the 32-bit storage to 16-bit access conversion).

    Regards