Altera Corporation
2–75
October 2007
Stratix II GX Device Handbook, Volume 2
Stratix II GX Transceiver Architecture Overview
The pattern detector is defaulted to the A1A2 mode. Only the positive
disparity is detected in this mode.
Manual Alignment Modes
The word aligner has three manual alignment modes (7-, 10-, and 16-bits)
when the transceiver data path is in single-width mode. The 10- and 7-bit
alignment modes are used with 8B/10B code and the 16-bit alignment
mode is for scrambled or non-scrambled data.
7-bit Alignment Mode
In the 7-bit alignment mode (use the 8B/10B encoded data with this
mode), the module looks for the 7-bit alignment pattern you specified in
the MegaWizard Plug-In Manager in the incoming data stream. The 7-bit
alignment mode is useful because it can mask out the three most
significant bits of the data, which allows the word aligner to align to
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. Masking the three MSBs allows
the word aligner to resolve all three alignment patterns synchronized to
it. The word aligner places the boundary of the 7-bit pattern in the LSByte
position with bit positions
[0..7]
. The true and complement of the
patterns is checked.
Use the
rx_enapatternalign
port to enable the 7-bit manual word
alignment mode. When the
rx_enapatternalign
signal is high, the
word aligner detects the specified alignment patterns and realigns the
byte boundary if needed. The
rx_syncstatus
port is asserted for one
parallel clock cycle to signify that the word boundary was detected across
the current word boundary and has synchronized to the new boundary,
if a rising edge was detected previously on the
rx_enapatternalign
port. You must differentiate if the acquired byte boundary is correct,
because the 7-bit pattern can appear between word boundaries. For
example, in the standard 7-bit alignment pattern -7'b1111100, if a K28.7 is
followed by a K28.5, the 7-bit alignment pattern appears on K28.7,
between K28.7 and K28.5, and also again in K28.5 (refer to
Figure 2–59
).
Figure 2–59. Cross Boundary 7-Bit Comma When /K28.7 is Followed by /K28.5
0
1
0
1
1
1
1
1
0
0
0
0
0
1
1
1
1
1
0
0
K28.7
K28.5
7-bit comma-
7-bit comma+
7-bit comma-
Содержание Stratix II GX
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