2–190
Altera Corporation
Stratix II GX Device Handbook, Volume 2
October 2007
Native Modes
LOW level on the
rx_a1a2size
port configures the word aligner to
align to a 16-bit A1A2 pattern and a high level configures it to align to a
32-bit A1A1A2A2 pattern.
You can configure the word aligner to flip the alignment pattern bits
programmed in the MegaWizard and compare it them with the incoming
data for alignment. This feature offers flexibility to the SONET/SDH
system for either an MSBit to LSBit or LSBit to MSBit data transfer.
Table 2–43
lists word alignment patterns that you must program in the
MegaWizard based on the bit-transmission order and the word aligner
bit-flip option.
The behavior of the SONET/SDH word aligner control and status signals
along with an operational timing diagram are explained in
“Manual
SONET/SDH Alignment Mode (Two Consecutive 8-bit Characters
(A1A2) or Four Consecutive 8-bit Characters (A1A1A2A2))” on
page 2–78
.
OC-96 Word Alignment
In OC-96 configuration, the word aligner is only allowed to align to a
A1A1A2A2 pattern, so input port
rx_a1a2size
is unavailable. Barring
this difference, the OC-96 word alignment operation is similar to that of
the OC-12 and OC-48 configurations.
OC-48 Byte Serializer and Deserializer
The OC-48 transceiver data path includes the byte serializer and
deserializer to allow the PLD interface to run at a lower speed. The OC-12
configuration does not use the byte serializer and deserializer blocks.
The byte serializer and deserializer blocks are explained in the sections
“Byte Serializer” on page 2–32
and
“Byte Deserializer” on page 2–112
,
respectively. The OC-48 byte serializer converts 16-bit data words from
Table 2–43. Word Aligner Settings
Serial Bit Transmission
Order
Word Alignment Bit
Flip
Word Alignment Pattern
MSBit to LSBit
On
1111011000101000
(16'hF628)
MSBit to LSBit
Off
0001010001101111
(16'h146F)
LSBit to MSBit
Off
0010100011110110
(16'h28F6)