Symbol Alignment And Detection (Comma Detection); Summary; Bypassing - Xilinx Virtex-4 RocketIO User Manual

Chapter 3: PCS Digital Design Considerations

Symbol Alignment and Detection (Comma Detection)

Summary

In addition to 8/10-bit symbol alignment detection, the RocketIO MGT has been expanded
to detect and align to 32-bit boundary to support A1, A2 sequences of SONET applications.
The 32-bit SONET aligner was designed specifically for SONET and might not be suitable
for generic applications. The ability to detect symbols, and then align either to 1-, 2-, or 4-
word boundaries is included. The traditional alignment block has the RXSLIDE input that
allows the user to slide or slip the alignment by one bit in each 32- and 40-bit mode at any
time when any applications cannot be supported with the SONET or 10-bit comma
definitions.
The following ports and attributes affect the function of the comma detection block:
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Bypassing

Comma detection is disabled when RXCOMMADETUSE is set to logic 0.
If RXCOMMADETUSE is set to logic 1, symbol/comma detection takes place.
See
Table 3-8: Deserializer Comma Detection Bypass
116
RXCOMMADETUSE
ENMCOMMAALIGN
ENPCOMMAALIGN
ALIGN_COMMA_WORD[1:0]
MCOMMA_32B_VALUE[31:0]
MCOMMA_DETECT
PCOMMA_32B_VALUE[31:0]
PCOMMA_DETECT
COMMA_10B_MASK[9:0]
RXSLIDE
RXINTDATAWIDTH[1:0]
COMMA32
PMA_BIT_SLIP
RXSYNC
Table 3-8.
Signal
RXCOMMADETUSE
ENPCOMMAALIGN
ENMCOMMAALIGN
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Comma detection is disabled.
0
Comma detection is enabled. COMMA is detected
1
based on Table 3-9.
Comma alignment is disabled. RXDATA reflects how
00
the data is output from the deserializer.
Comma alignment is enabled. The comma is defined
by COMMA_10B_MASK and
01
MCOMMA _32B_VALUE.
Comma alignment is enabled. The comma is defined
by COMMA_10B_MASK and
10
PCOMMA _32B_VALUE.
Comma alignment is enabled. The comma is defined
by COMMA_10B_MASK and MCOMMA
11
_32B_VALUE, PCOMMA_32B_VALUE.
Function
Virtex-4 RocketIO MGT User Guide
UG076 (v4.1) November 2, 2008
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