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EDMA transfer

daisy wu
Prodigy 130 points

Hi  Everyone,

          I have a problem here and need your help.   In omap137,  the EDMA3 has two EDMA3TCs,  so can I make two transfers concurrently?  I want to transfer data from SDRAM to McAsp ,  and some other data from SDRAM to L2RAM   at   the same time,  Would it influence the transition speed?

  • 0
    TI__Mastermind 30150 points

     

    You are correct, the 2 transfers can run concurently on the SCR if 2 different EDMA3 TCs are used. But keep in mind that 2 requestors (the2 TCs) will try to access the same ressource (SDRAM). There is a way to program which TC has priority on the SCR (see EDMA QUEPRI register).

    To optimize the transfers you should place the small transfer on a Higher priority Queue in the EDMA CC. Also to maximize the throughput take a ACNT that matches the bus widths.

    It might be worth to look at the following documents. It does not relate completly to OMAP-L13x as it is for different devices but it still should give you information on the basic concepts:
             DM6467 architecture and throughput overview (SPRAAW4B)
             TCI6482 EDMA3 Performance (SPRAAG8)

  • 0 in reply to AnBer
    TI__Guru*** 125430 points

    Make sure to utilize the block of SRAM that sits of the SCR.  If you can have one block of data in SDRAM and the other in SRAM then you will be able to have truly parallel data transfers.

  • 0 in reply to Brad Griffis
    Prodigy 130 points

    Thanks  for  your  help.  I'll  check later.

    There is another question.  I used CCS3.3 emulating   omap137.   What's  the difference between  Profile--->clock---->setup--->cycles( default)  and  CPU execute cycles? The measure results  are  not even close.   I want to know the time elapsed during a certain function,  which one should I use?

  • 0 in reply to daisy wu
    TI__Guru*** 125430 points

    You're off topic.  Please start a new thread.