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F28M35 SRAM

yong li64142
Prodigy 110 points


Hello,

I need more RAM for my DSP calculation.  Can F28M35 do the same thing like 28335 to add external sram chips? I found that 28335 has some pins defined as XA, and XD functions, I didn't find them in the F28M35 datasheet.

 

 

  • 0
    TI__Expert 4595 points

    Hi Yong,

    Very much like the 28335 the F28M35 supports external SRAM with data and address pins.  See Chapter 14 of the F28M35 Technical Reference Manual for details.  The EPI on F28M35 supports SDRAM, host-bus mode and general-purpose mode.  All of these modes are detailed in the TRM. 

    If you are looking for the same functionality in external memory support on the F28M35 as with the 28335, you will find it in the EPI.  Take a close look at host-bus mode with pin connections on page 715 for 16-bit SRAM.

    Regards, 
    Jeff 

     

    7002.F28M35 TRM spruh22[1].pdf

  • 0 in reply to Jeff Stafford
    Prodigy 110 points

    Hi Jeff,

    Thanks for your reply. I checked Chapter 14 for EPI feature in the TRM. But that is for the M3 core feature. How do I map the M3 EPI memory to the C28 core? I need more memory for the C28 DSP function.

  • 0 in reply to yong li64142
    TI__Expert 4595 points

    Yong,

    Understood.  You are correct, direct access to the EPI on Concerto is only by the M3 and the M3 uDMA.

    To extend DSP processing RAM on Concerto you have the option to allocate more of the Shared Memory to the C28.  Did you notice the Shared Memory that both the M3 and C28 have access to?  There are (8) blocks of the Shared RAM  (S0-S7) that can be allocated to either M3 or C28 for write access.  So this gives you 64 KB of additional RAM allocation to C28.

    If this is not enough, then you have the option to manage external RAM with the M3 DMA transferring blocks of data between EPI and Shared RAM.  Not ideal, but this is an option.

    Jeff