2–88
Altera Corporation
Stratix II GX Device Handbook, Volume 2
October 2007
Receiver Modules
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 2–66
).
Figure 2–66. Cross Boundary 7-Bit Comma When /K28.7 is Followed by /K28.5
Manual 8-bit Alignment Mode
You can enable the 8-bit alignment mode in the double-width mode. This
mode aligns to the 8-bit alignment pattern you specified in the
MegaWizard.
The byte boundary is locked after the first alignment pattern is detected
and after the rising edge of the
rx_enapatternalign
signal. The
detected pattern is placed in the LSByte of the 16-bit word. If the byte
boundary changes, the
rx_enapatternalign
port must be deasserted
and reasserted to enable the alignment circuit to search for and align to
the next available alignment pattern. On the rising edge of the
rx_enapatternalign
signal, the word aligner locks onto the first
alignment pattern detected and places the detected pattern in the data
stream on the LSByte position. In this scenario,
rx_patterndetect
is
asserted to signify that the alignment pattern has been aligned. The
rx_syncstatus
signal is also asserted to signify that the word
boundary has been synchronized.
Manual 10-Bit Alignment Mode
You can configure the word aligner to align to a 10-bit word boundary.
The internal word alignment circuitry shifts to the correct word boundary
if the alignment pattern you specified in the pattern detector is detected
in the data stream. The word aligner then puts the alignment pattern in
the LSByte of the data path.
In 10-bit manual word alignment mode, the word aligner looks for the
10-bit alignment pattern after detecting a rising edge on the
rx_enapatternalign
signal. On finding the alignment pattern, the
word aligner locks the word boundary and asserts the
rx_syncstatus
signal. The
rx_syncstatus
signal remains high until it sees another
rising edge on the
rx_enapatternalign
. After detecting a rising edge
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-