Xilinx Virtex-6 FPGA

224 www.xilinx.com Virtex-6 FPGA GTX Transceivers User Guide
UG366 (v2.5) January 17, 2011
Chapter 4: Receiver
COMMA_DOUBLE Boolean Specifies whether a comma match consists of either a comma plus or a
comma minus alone, or whether both are required in the sequence.
FALSE: The plus comma (PCOMMA) and minus comma (MCOMMA)
are handled separately. An individual match for either can lead to
comma detection and alignment.
TRUE: A comma match consists of a comma plus followed
immediately by a comma minus. The match pattern is 20 or 16 bits (as
determined by RX_DATA_WIDTH).
When COMMA_DOUBLE is TRUE, PCOMMA_DETECT must be the
same as MCOMMA_DETECT, and RXENPCOMMAALIGN must be the
same as RXENMCOMMAALIGN.
MCOMMA_10B_VALUE 10-bit
Binary
Defines comma minus to raise RXCOMMADET and align the parallel
data. Reception order is right to left. (MCOMMA_10B_VALUE [0] is
received first.) The default value is 10’b1010000011 (K28.5). This
definition does not affect 8B/10B encoding or decoding.
MCOMMA_DETECT Boolean Controls the raising of RXCOMMADET on comma minus.
FALSE: Do not raise RXCOMMADET when comma minus is detected.
TRUE: Raise RXCOMMADET when comma minus is detected. (This
setting does not affect comma alignment.)
PCOMMA_10B_VALUE 10-bit
Binary
Defines comma plus to raise RXCOMMADET and align parallel data.
Reception order is right to left. (PCOMMA_10B_VALUE [0] is received
first.) The default value is 10’b0101111100 (K28.5). This definition
does not affect 8B/10B encoding or decoding.
PCOMMA_DETECT Boolean Controls the raising of RXCOMMADET on comma plus.
FALSE: Do not raise RXCOMMADET when comma plus is detected.
TRUE: Raise RXCOMMADET when comma plus is detected. (This
setting does not affect comma alignment.)
SHOW_REALIGN_COMMA Boolean Defines whether a comma that causes realignment is brought out to the
FPGA RX.
FALSE: Do not bring the realignment comma to the FPGA RX. This
setting reduces the RX datapath latency.
TRUE: Bring the realignment comma to the FPGA RX.
SHOW_REALIGN_COMMA = TRUE should not be used when
COMMA_DOUBLE = TRUE.
Table 4-35: RX Comma Alignment Attributes (Cont’d)
Attribute Type Description
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