Alignment Boundaries; Manual Alignment - Xilinx Virtex-6 FPGA User Manual

Chapter 4: Receiver

Alignment Boundaries

The allowed boundaries for alignment are defined by ALIGN_COMMA_WORD. The
spacing of the possible boundaries is determined by RX_DATA_WIDTH, and the number
of boundary positions is determined by the number of bytes in the RXDATA interface
(refer to
boundaries that can be selected.
X-Ref Target - Figure 4-26
RX_DATA_WIDTH ALIGN_COMMA_WORD
8/10
(1-byte)
8/10
2 (Even Boundaries Only)
(1-byte)
16/20
(2-byte)
16/20
2 (Even Boundaries Only)
(2-byte)
32/40
(4-byte)
32/40
2 (Even Boundaries Only)
(4-byte)

Manual Alignment

RXSLIDE can be used to override the automatic comma alignment and shift the parallel
data. RXSLIDE is driven High for one RXUSRCLK2 cycle to shift the parallel data by one
bit. RXSLIDE must be Low for at least 16 RXUSRCLK2 cycles before it can be used again.
Figure 4-27
RX_SLIDE_MODE = PCS before and after the data shift.
www.BDTIC.com/XILINX
220
Table 4-56, page 269
1 (Any Boundary)
1 (Any Boundary)
1 (Any Boundariy)
Figure 4-26: Comma Alignment Boundaries
shows the waveforms for manual alignment using RXSLIDE in
www.xilinx.com
for RX_DATA_WIDTH settings).
RXDATA Byte 3 RXDATA Byte 2
RXDATA Byte 3 RXDATA Byte 2
Virtex-6 FPGA GTX Transceivers User Guide
Figure 4-21 shows the
Possible RX Alignments
(Grey = Comma Can Appear on Byte)
RXDATA Byte 0
Invalid Configuration
RXDATA Byte 1 RXDATA Byte 0
RXDATA Byte 1 RXDATA Byte 0 RXDATA Byte 0
RXDATA Byte 1 RXDATA Byte 0 RXDATA Byte 0
RXDATA Byte 1 RXDATA Byte 0 RXDATA Byte 0
UG366_c4_24_102910
UG366 (v2.5) January 17, 2011