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C5515 circular buffer size over 4k

Mette Bertelsen
Prodigy 30 points

Hi.

I've been having troubles implementing a circular buffer larger than 4096. I've read the data sheet for the processor (SPRS645F) and found that it contains 8 blocks of 4K x 16-Bit for the DARAM and assume that's causing my issues.

The size I need is about 48k

Is there any workaround to this limitation in size? 

Best regards,

Mette 

  • 0
    TI__Genius 12575 points

    Hi,

    Have you looked at section 6.11 of the document at:

    http://focus.ti.com/lit/ug/spru371f/spru371f.pdf

    Regards

     Vasanth

     

  • 0 in reply to Vasantha K
    Prodigy 30 points

    Hi.

    Thanks for your reply.

    Yes, I've read the documentation, but it doesn't mention the size issues. 

    My circular buffer works fine with values < 4096

    If I define this:

    MOV #48000, BK03
    BSET AR0LC
    AMOV #02000h, XAR0 
    MOV #02000h, BSA01

    I however recieve the following error on the first line:

     [W9999] Using MMR address

    And the audio output is noise.

    In my linker file the MMR is defined as:

    MMR (RWIX): origin = 0x000000, length = 0x0000c0 /* MMRs */
    DARAM0 (RWIX): origin = 0x0000c0, length = 0x00ff40 /* 64KB - MMRs */

    But when writing to 0x2000, I'm unsure if there are any MMR values amongst them I've read the documentation 3.11 in spru371f and can't really find any indication of any MMR's being in this range.

    Regards,

    Mette

  • 0 in reply to Mette Bertelsen
    TI__Guru* 84285 points

    The instruction to load a constant directly to register BK03 only allows a 12-bit constant, so you have to write to BK03 with a memory-mapped register write.  The assembler is converting the instruction for you, but you usually want to add the "mmap" qualifier, like so.  If you don't, and XDP is not zero, your write will be to a random memory location rather than BK03.

    .mmregs
    MOV #48000, mmap(@BK03)
  • 0 in reply to Archaeologist
    Prodigy 30 points

    Thanks for your reply. That worked! :)