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uPP protocol

whitsydaddy
Prodigy 190 points


Hello,

I have 2 hopefully quick questions about the uPP protocol.  First with the uPP powered and configured with one channel set to receive and another to transmit will the wait line be asserted is the dma descriptors have not been set yet?  If that is the case will it assert again after the current dma transfer occurs and a new one has not been programmed yet?

My second question has to do with the 2D dma buffer scheme.  What is the advantage to using multiple lines in the 2D data buffer window? So if my dma transfer was set to 4k bytes, should I just set it as one line in the window or multiple lines?   thanks in advanced, Scott

  • 0
    TI__Expert 8890 points

    Scott,

    The uPP receive channel will not assert WAIT simply because no transfer has been programmed.  Depending on how you configure the peripheral, WAIT will only be asserted during emulation halt (i.e. if you connect to the device with JTAG and halt execution).  During normal operation, the receive channel never asserts WAIT.

    If you use small or moderate-sized data buffers, then you probably don't need to use the 2D DMA features.  There are several things that 2D DMA transfers let you do:

    1. Use end-of-line interrupts to trigger application callbacks without waiting for the end of the overall transfer
    2. Use very large data buffers (max line size is 64KB, but you can have up to 64K lines in the overall transfer)
    3. Use data buffers that are not monolithic in memory (ex. line size 1024 bytes, line offset 2048 bytes)
    4. Repeatedly transfer a single line in memory (ex. line size 1024 bytes, line offset 0 bytes)

    Hope this helps.

  • 0 in reply to Joe Coombs
    Prodigy 190 points

    Thanks for the answer Joe