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About the DDR3 memory space.

Jason Gao
Intellectual 720 points
Other Parts Discussed in Thread: TMS320C6678

Hi All:

In the datasheet of TMS320C6678, DDR3 EMIF occupies 2G Bytes of memory space. But

in document SPRUGV8C, it says that "8GB address space available over one or two chip selects".

In out application, DDR3 should be used as more as possible. We connect 2 chip selects with

16 DDR3s (2Gb * 16 = 4GB).  Do you know if the 4GB can all be used? Thank you very much.

  • 0
    TI__Guru* 84110 points

    Jason,

    If the connections and timing and layout meet the board design requirements, then you can use up to 8GB of DDR memory. Your 4GB memory can all be used by some combination of the 8 DSP cores in the C6678.

    Please look at the MSMC User's Guide to learn more about how the MPAX module works and how it gives access to the DDR memory beyond the 2GB range.

    Regards,
    RandyP

     

    If you need more help, please reply back. If this answers the question, please click  Verify Answer  , below.

  • 0 in reply to RandyP
    TI__Expert 6815 points

    Jason, just to Randy's reply...all accesses to DDR3 go via the MSMC module. The MSMC users guide will explain how the address space is expanded from 32 to 36-bits. The MSMC presents a 36-bit address to the DDR3 controller of which the controller uses the lower 33 bits for external memory addressing. This 33-bit address space is how we get a total of 8GB.