DS730 Datasheet, PDF (31/46 Pages) Xilinx, Inc – LogiCORE IP Video Direct

LogiCORE IP Video Direct Memory Access v1.1
Basic Write Operation
In “Write Only” mode, the Video DMA can perform write operations in a number of different ways, all of which
follow the same basic process. The basic write operation of the Video DMA is as follows:
1. The Video DMA sends a “write command” to the VFBC.
2. After the command has been written, the Video DMA can begin transferring the data to the VFBC.
3. The Video DMA inputs data on the vdma_wd port,
4. The Video DMA then outputs the data to the VFBC on the vfbc_wd port.
The Video DMA uses FIFO flow control signals on the vdma_wd and vfbc_wd ports to control the flow of data.
More detailed descriptions of the different write operations can be found in the sections that follow.
Basic Read/Write Operation
In “Read/Write” mode, the Video DMA can simultaneously perform read and write operations in a number of
different ways, all of which follow the basic read and basic write operations described in the two previous sections.
The read side and write side share one VFBC CMD bus. As a result, there is an added restriction that only one side
can write a command to the VFBC at a time.
Command Input Mode
When configured in “Write Only” mode, the vdma_wcmd port can be used to drive the operation of the Video DMA.
A write command that is written to the vdma_wcmd port is then written by the Video DMA to the VFBC by way of
the vfbc_cmd port. Once the command has been written, the full transfer can begin. See Figure 5 for a view of
multiple write transactions. See Figure 6 for a view of the write command that is written to the VFBC. Once the
write transaction begins, the vdma_wd_full pin should be used to control the writing of data into the Video DMA.
Note: The vfbc_cmd_idle signal should be active before a command is written to the vdma_wcmd port.
X-Ref Target - Figure 5
Figure 5: Write Command Interface, Multiple Transactions
DS730 September 21, 2010
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Product Specification