DS730 Datasheet, PDF (32/46 Pages) Xilinx, Inc – LogiCORE IP Video Direct

X-Ref Target - Figure 6
LogiCORE IP Video Direct Memory Access v1.1
Figure 6: Write Command Interface, Write Command
When configured in “Read Only” mode, the Video DMA operates very similarly to the way it does in the write
operation shown in Figure 5. There are two exceptions:
1. Read commands are written in on the vdma_rcmd port instead of the vdma_wcmd port.
2. The Video DMA uses the vfbc_rd and vdma_rd ports to transfer the data instead of the vdma_wd and
vfbc_wd ports.
See Figure 7 for a view of the read command that is written to the VFBC. Once the read transaction begins, the
vdma_rd_empty pin should be used to control the reading of data from the Video DMA.
X-Ref Target - Figure 7
Figure 7: Read Command Interface, Read Command
The format of the commands input on the vdma_wcmd or vdma_rcmd ports matches the format of the VFBC
commands (see the "Command Format" section for more details), with two exceptions:
1. For Command Word 1, the Write_NotRead (Bit 31) is not used.
2. When “Allow Non-Aligned Transfers” is selected, the X_Size and Start Address do not have to conform
to the 128-byte boundary requirement.
DS730 September 21, 2010
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Product Specification