DS879 Datasheet, PDF (6/7 Pages) Xilinx, Inc – Video Remapper v1.00a

Video Remapper v1.00a
Guidelines on Driving s_axis_tvalid
Once s_axis_tvalid is asserted, no interface signals (except the Video Remapper core driving s_axis_tready)
may change value until the transaction completes (s_axis_tready and s_axis_tvalid are high on the rising
edge of aclk). Once asserted, s_axis_tvalid may only be de-asserted after a transaction has completed.
Transactions may not be retracted or aborted. In any cycle following a transaction, s_axis_tvalid can either be
de-asserted or remain asserted to initiate a new transfer.
X-Ref Target - Figure 3
Figure 3: Example of READY/VALID Handshake, Start of a New Frame
Guidelines on Driving m_axis_tready
The m_axis_tready signal may be asserted before, during or after the cycle in which the Video Remapper core
asserted m_axis_tvalid. The assertion of m_axis_tready may be dependent on the value of m_axis_tvalid.
A slave that can immediately accept data qualified by m_axis_tvalid, should pre-assert its m_axis_tready
signal until data is received. Alternatively, m_axis_tready can be registered and driven the cycle following
VALID assertion. It is recommended that the AXI4-Stream slave should drive READY independently, or pre-assert
READY to minimize latency.
Start of Frame Signals - m_axis_tuser, s_axis_tuser
The Start-Of-Frame (SOF) signal, physically transmitted over the AXI4-Stream TUSER[0] signal, marks the first
pixel of a video frame. The SOF pulse is 1 valid transaction wide, and must coincide with the first pixel of the frame,
as seen in Figure 3. The SOF signal serves as a frame synchronization signal, which allows downstream cores to
re-initialize, and detect the first pixel of a frame. The SOF signal may be asserted an arbitrary number of aclk cycles
before the first pixel value is presented on DATA, as long as a VALID is not asserted.
End of Line Signals - m_axis_tlast, s_axis_tlast
The End-Of-Line (EOL) signal, physically transmitted over the AXI4-Stream TLAST signal, marks the last pixel of a
line. The EOL pulse is 1 valid transaction wide, and must coincide with the last pixel of a scan-line.
DS879 October 16, 2012
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