Altera Corporation
2–85
October 2007
Stratix II GX Device Handbook, Volume 2
Stratix II GX Transceiver Architecture Overview
Figure 2–65. Word Aligner Components, Double-Width Mode
Pattern Detector Module
The pattern detector matches a pre-defined comma to the current word
boundary. If the pattern detector locates the correct alignment pattern, the
optional
rx_patterndetect
signal is asserted for the duration of one
clock cycle to signify that the alignment pattern exists in the current word
boundary. The pattern detector module only indicates that the signal
exists and does not modify the word boundary.
You can program and then specify in the MegaWizard a 7-bit, 8-bit, 10-bit,
16-bit, 20-bit, or 32-bit, pattern for the pattern detector to recognize in
double-width mode. For the 7-bit, 10-bit, and 20-bit patterns, the actual
and complement of the alignment patterns are checked and used with
8B/10B coding. For the 8-bit, 16-bit, and 32-bit alignment patterns, only
the actual patterns are checked, not the complements. These patterns are
used for scrambled coding or non-encoded data.
7-Bit Pattern Mode
In the 7-bit pattern detection mode, the pattern detector matches the
seven least significant bits of the 10-bit alignment pattern in the LSByte as
specified in the MegaWizard in the current word boundary. The pattern
detector checks both positive and negative disparities in this mode.
The 7-bit pattern mode can mask out the three most significant bits of the
data, which allows the pattern detector to recognize multiple alignment
patterns. For example, in the 8B/10B encoded data, a /K28.5/
(b’0011111010), /K28.1/ (b’0011111001), and /K28.7/ (b’0011111000) share
seven common LSBs, so masking the three MSBs allows the pattern
Double-Width Mode
Pattern Detector and
Manual Alignment Mode
7-Bit
Mode
32-Bit
Mode
16-Bit
Mode
8-Bit
Mode
20-Bit
Mode
10-Bit
Mode
Содержание Stratix II GX
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