Altera Corporation
2–87
October 2007
Stratix II GX Device Handbook, Volume 2
Stratix II GX Transceiver Architecture Overview
32-Bit Pattern Mode
You enable the four consecutive 8-bit character (A1A2A3A4 or
A1A1A2A2) detection in the MegaWizard. You specify the 32-bit
alignment pattern in the MegaWizard and it is oriented with the MSB first
and the LSB last. A1 represents the least significant byte, which consists
of bits
[7..0]
. A4 represents the most significant byte, which consists of
bits
[31..24]
. Therefore, the alignment pattern is specified as
[A4,A3,A2,A1] in the MegaWizard. Only the actual alignment pattern
you specified in the MegaWizard is detected in this mode.
Manual Alignment Modes
The word aligner has six manual alignment modes (7-, 8- 10-, 16-, 20- and
32-bits) when the transceiver data path is in double-width mode. The 7-,
10-, and 20-bit alignment modes are used with 8B/10B encoded data.
Both the actual and complement of the alignment pattern are checked for
these modes. The 8-, 16-, and 32-bit alignment modes are for scrambled or
non-scrambled data. Only the actual alignment pattern is checked for
these modes.
Manual 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.
In 7-bit manual word alignment mode, the word aligner looks for the 7-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
on the
rx_enapatternalign
signal, the word aligner starts looking for
the 7-bit word alignment pattern again and asserts the
rx_syncstatus
signal once it finds the 7-bit alignment pattern. 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