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HW Memory Design Question for C6748 Based off the LCDK

Chris Koplan1
Intellectual 410 points
Other Parts Discussed in Thread: OMAP-L138, OMAPL138

I am still very new to the C6748 DSP I am very confused by the memory section of the schematic that is supplied by the development kit.  (OMAP-L138_C6748 LC Dev Kit Ver A6a).  From the processor documentation I understand there are two standard memory interfaces (EMIFA, EMIFB) available to the processor for various different purposes.  Where I start to get confused is that the block diagram has the "DDR-II" memory hooked up to a DDR bus.  I then scroll down to the scematic itself and I find all the pins named as "DDR_A_13" and such.  I can't find any reference to this pin description in the C6748 documentation and thus am condused.  Is this really the EMIFB bus or is there an additional DDR bus?  I can't find any additional rerfernce to a DDR bus so I am assuming it is the EMIFB bus.  

  • 0
    TI__Guru** 116100 points

    Hi Chris,

    What processor are you using ?

    OMAPL38 device has support only for EMIFA peripheral interface whereas OMAPL137 has support both EMIFA and EMIFB interfaces.

    In OMAPL138, the EMIFA is for to interface NAND,NOR and SRAM devices.

    OMAPL138/C6748 LCDK board had DDR2 memory which is connected through separate DDR bus.

    Please refer to the OMAPL137 & OMAPL138 data sheets to know more.

  • 0 in reply to Titusrathinaraj Stalin
    Intellectual 410 points

    Thank you.  I have been using both the OMAPL138, C6748 and OMAPL137 as possibilities for my next application.  As a result I had gotten a little lost as to where the differences are and very much appreciate your help laying it out clearly for me.  

    Now my understanding for the OMAPL137 is that the EMIFB is really meant for SDRAM type devices (OMAP L137).   My understanding is that DDR (OMAP L138 and C6748) is really just a improved SDRAM.  As result these interfaces essentially perform the same function for the two processors but the OMAPL138 will have improved performance due to the faster memory.  Is that accurate about how these two are different and generally meant to be used?  

    Thanks.

  • 0 in reply to Chris Koplan1
    TI__Mastermind 43660 points

    Hello Chris,

    Unfortunately there is no detailed document available that depicts the difference between above mentioned devices.

    However you could find some high level differences in the below link.

    http://processors.wiki.ti.com/index.php?title=C674x/OMAPL1x_Introductory_Information

    Now my understanding for the OMAPL137 is that the EMIFB is really meant for SDRAM type devices (OMAP L137).   My understanding is that DDR (OMAP L138 and C6748) is really just a improved SDRAM.  As result these interfaces essentially perform the same function for the two processors but the OMAPL138 will have improved performance due to the faster memory.  Is that accurate about how these two are different and generally meant to be used?  

    Though the DDR is advanced version of SDRAM, you cannot interface DDR with EMIFB. You must have a dedicated DDR controller to interface DDR.

    Based on the performance requirement, you could opt either DDR or SDRAM.

    Note that OMAPL137 doesn't support for DDR interface.

     

    Regards,
    Senthil

     

  • 0 in reply to Senthilkumar Srinivasan
    Intellectual 410 points

    Thanks for that link.  I wish I had found that before as it gave a really good break down and cleared things up for me.