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C6748 SD Card DMA read performance

Marco Giochi
Prodigy 30 points
Other Parts Discussed in Thread: OMAPL138, SYSCONFIG

Hi,

I'm starting a new project based on C6748 (LCDK 6748 board) and I need, at start of my program, to read one single file from SD card to DDR2 (size = 100 MBytes).

I'm interest to analize the best fast approach for this task (without any other concurrent task) because I need to read the file one time and only at start of DSP firmware.

About this argument there is two document OMAPL138_BIOSPSP_Datasheet.pdf and C6748_BIOSPSP_Datasheet.pdf wich report two different throughput rate (both Blockmedia driver) between L138 (11 MBps) and C6748 (2.20 MBps).

Why is it too big differences on MMCSD read performance between this two devices which I know to have the same peripheral ???

Thank in advance for your attention,
Regards,

Marco

  • 0
    TI__Guru* 84110 points

    Marco,

    The two packages are run on different devices and perhaps use different methods. Since you are using the C6748 device, the throughput observed in the C6748_BIOSPSP_Datasheet.pdf document is the one you will want to pursue.

    Personally, I too find it interesting that there is such a difference. But I do not know what specifically would make that difference and am not in a position to determine the reason. Sorry.

    Regards,
    RandyP

  • 0
    TI__Mastermind 35645 points

    Hi Marco,

    Thanks for your post.

    Yes, there are big diffrences on MMCSD read/write performance between OMAPL1138 & C6748 after comparing the throughput benchmark results from bios psp datasheets of both. This could be mainly because of the MMCSDBusWidth difference between OMAPL138 & C6748 h/w's and there are appropriate #defines needs to be configured between hw_sysconfig_OMAPL13.h & hw_sysconfig_C6748.h as well soc_OMAPL13x.h & soc_c674x.h.

    Please check the SD driver code, you will find the differences in HWREG configuration between OMAPL138 & C6748 in both non-OS (Starterware) & BIOS driver cases. I think, you are aware that, OMAPL138 do not have direct support for SD driver example project without usb adaptor.

    File: mmcsd.c
    Function:MMCSDBusWidthSet()

    Please refer the below E2E thread for more details:

    http://e2e.ti.com/support/dsp/omap_applications_processors/f/42/t/160352.aspx

    Also, if you need C6748 StarterWare SD Card Example, you shall find the same from the below E2E thread:

    http://e2e.ti.com/support/embedded/starterware/f/790/t/283373.aspx

    Please experiment the read/write throughput performance from the sample projects available in the above E2E threads.

    Thanks & regards,

    Sivaraj K

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