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Absolute placement of variable fails

Bernd Erbe
Expert 2065 points

Hello,

I'm working with a C6678 on an EVM. Goal is to get data copied into L2SRAM directly (without indirection and memcpy, e.g. via DDR). Therefore I have to questions:

-Is it possible to copy data directly into L2SRAM with SRIO (e.g. from an FPGA)? Should be only an absolute address for the data transfer in my opinion...
-I used the '#pragma LOCATION' to place a variable at an absolute address in the L2SRAM. Compiling works, but the variable dissappeared from the memory map. How can I set a variable at an absolute address to reserve the memory?

Best Regards,
Bernd

  • 0
    TI__Guru* 84110 points

    Bernd,

    Yes, you can copy directly into L2 SRAM by using the Global L2 SRAM address for the SRIO destination address. In the datasheet memory map, look for the CorePac0 L2 SRAM, to see the global address for CorePac0's L2 SRAM.

    I have never used #pragma LOCATION. Does the variable reside at the correct location, it just does not show up in the memory map? Or does the application fail to work or the symbol is not defined within the code?

    Regards,
    RandyP

  • 0 in reply to RandyP
    Expert 2065 points

    Hello Randy,

    thanks for your answer. Does it make a difference if I use L2SRAM (0x00800000) or CorePac0 L2SRAM (0x10800000)? If yes, what is the difference?

    I'm not sure what I have changed, but now the pragma works (output in the map is a .TI.bound statement). So far...

    Best Regards,
    Bernd

  • 0 in reply to Bernd Erbe
    TI__Guru* 84110 points

    Bernd,

    If you use 0x00800000, which CorePac's L2SRAM would you expect to be reaching? If you think it is CorePac0, what address would you then use for CorePac1?

    The description in the datasheet's memory map is "Local L2 SRAM". Please see the details later in the datasheet in Section 5.1.3 L2 Memory. That section describes how the L2 memory within a CorePac is used and addressed.

    Regards,
    RandyP

  • 0 in reply to RandyP
    Expert 2065 points

    Hello Randy,

    thanks, this chapter clarified everything.

    Best Regards,
    Bernd