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Max EMIF speed on DM368

Alexander Khvilivitzky
Expert 1055 points


Dear experts!
I'm trying to find out what maximun data transfer rate I can achive over EMIF on DM368. I need to read as fast as possible from a "black-box" device. The interface on the device can be flexible. Based on the numbers in the DM368 spec I came up with about 54MHz  in async mode. Is this close to truth? Is there any way to achieve higher speeds?

Thanks,

A.

  • 0
    TI__Genius 9510 points

    Alexander,

    ~50MHz is about the maximun data transfer for EMIFA.  Peerhaps the transfer can be accomplish using another interface (i.e. usb, ethernet)

    Marcus

  • 0 in reply to Marcus Cooksey
    Expert 1055 points

    Marcus,

    first, even at 50MHz and a 16-bit bus EMIF is faster than what USB or Ethernet can provide on the DM368.

    Second, in a synchronous burst mode EMIF supposedly can work at 66MHz clock (SPRS668A, p.103). The overhead can be very low with long bursts. What limits the burst length on EMIF in a synchronous mode (when used not with OneNAND flash, but with an interface that could be optimized for speed)?

    Regards,

    A.

  • 0 in reply to Alexander Khvilivitzky
    Expert 1055 points

    I'm still trying to figure out the fastest AEMIF speed on the DM368. Need help interpreting the data sheet (SPRS668B).

     

    Asynchronous mode.

    Table 6-22, p.101:

    EMIF read cycle = (RS + RST + RH + 3) * E >= 6 * E,

    where E = 0.5 (PLL1CSYSCLK4 period, ns) (note 1 to Table 6-21).

     

    From Tables 3-2 and 3-4 I made a conclusion that max frequency for PLL1CSYSCLK4 is 170 MHz. => E = 0.5 (1 / 170) = 2.94 ns.

    So min EMIF read cycle time is 6*2.94 = 17.64 ns <-> 56.7 MHz.

     

    Synchronous mode.

     

    Table 6-22: synchronous burst read clock = 66 MHz.

    Waveforms on p.105 show that data is read each clock cycle during the burst.

    What limits the burst length?

     

     

    Are those conclusions correct (async read rate = 56.7 * 2 = 113 MB/s, sync burst read rate = 66 * 2 = 132 MB/s)?

    Thanks,

    A.