Xilinx Virtex-6 FPGA User Manual

Virtex-6 FPGA GTX Transceivers User Guide www.xilinx.com 145
UG366 (v2.5) January 17, 2011
TX 8B/10B Encoder
Table 3-12: TX Encoder Ports
Port Dir Clock Domain Description
TXBYPASS8B10B[3:0] In TXUSRCLK2 TXBYPASS8B10B controls the operation of the TX 8B/10B encoder
on a per-byte basis. It is only effective when TXENC8B10B is High
(8B/10B is enabled) and RX_DATA_WIDTH is {10, 20, 40}. See
Table 4-56, page 269 for additional information on
RX_DATA_WIDTH.
TXBYPASS8B10B[3] corresponds to TXDATA[31:24]
TXBYPASS8B10B[2] corresponds to TXDATA[23:16]
TXBYPASS8B10B[1] corresponds to TXDATA[15:8]
TXBYPASS8B10B[0] corresponds to TXDATA[7:0]
TXBYPASS8B10B[x] = 1, encoder for byte x is bypassed
TXBYPASS8B10B[x] = 0, encoder for byte x is used
TXCHARDISPMODE[3:0] In TXUSRCLK2 TXCHARDISPMODE and TXCHARDISPVAL allow the 8B/10B
disparity of outgoing data to be controlled when 8B/10B encoding
is enabled.
When 8B/10B encoding is disabled, TXCHARDISPMODE is used
to extend the data bus for TX interfaces with a width that is a
multiple of 10.
TXCHARDISPMODE[3] corresponds to TXDATA[31:24]
TXCHARDISPMODE[2] corresponds to TXDATA[23:16]
TXCHARDISPMODE[1] corresponds to TXDATA[15:8]
TXCHARDISPMODE[0] corresponds to TXDATA[7:0]
TXCHARDISPVAL[3:0] In TXUSRCLK2 TXCHARDISPVAL and TXCHARDISPMODE allow the 8B/10B
disparity of outgoing data disparity to be controlled when 8B/10B
encoding is enabled.
When 8B/10B encoding is disabled, TXCHARDISPVAL is used to
extend the data bus for 10- and 20-bit TX interfaces (see FPGA TX
Interface, page 128).
TXCHARDISPVAL[3] corresponds to TXDATA[31:24]
TXCHARDISPVAL[2] corresponds to TXDATA[23:16]
TXCHARDISPVAL[1] corresponds to TXDATA[15:8]
TXCHARDISPVAL[0] corresponds to TXDATA[7:0]
TXCHARISK[3:0] In TXUSRCLK2 TXCHARISK is set High to send TXDATA as an 8B/10B K
character. TXCHARISK should only be asserted for TXDATA
values representing valid K-characters.
TXCHARISK[3] corresponds to TXDATA[31:24]
TXCHARISK[2] corresponds to TXDATA[23:16]
TXCHARISK[1] corresponds to TXDATA[15:8]
TXCHARISK[0] corresponds to TXDATA[7:0]
TXCHARISK is undefined for bytes that bypass 8B/10B encoding.
TXENC8B10BUSE In TXUSRCLK2 TXENC8B10BUSE is set High to enable the 8B/10B encoder.
TX_DATA_WIDTH must be set to 10, 20, or 40 when the 8B/10B
encoder is enabled.
0: 8B/10B encoder bypassed. This option reduces latency.
1: 8B/10B encoder enabled.
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Xilinx Virtex-6 FPGA Specifications

General

Brand	Xilinx
Model	Virtex-6 FPGA
Category	Transceiver
Language	English