Altera Corporation
2–189
October 2007
Stratix II GX Device Handbook, Volume 2
Stratix II GX Transceiver Architecture Overview
Figure 2–140. OC-96 Data Path
SONET/SDH Serial Data Transmission Bit Order
Unlike Ethernet where the least significant bit of the data byte is
transferred first, SONET/SDH requires the most significant bit to be
transferred first and the least significant bit to be transferred last. To
facilitate MSBit to LSBit transfer, you must enable the following options
in the MegaWizard:
■
Flip Transmitter Input Data Bits (when used in transmit only or
duplex mode)
■
Flip Receiver Output Data Bits (when used in receive only or duplex
mode)
Depending on whether data bytes are transferred MSBit to LSBit or LSBit
to MSBit, you must select appropriate word aligner settings in the
MegaWizard.
Table 2–43
lists correct word aligner settings for each bit
transmission order.
OC-12 and OC-48 Word Alignment
SONET/SDH mode uses manual word alignment as described in
“Manual SONET/SDH Alignment Mode (Two Consecutive 8-bit
Characters (A1A2) or Four Consecutive 8-bit Characters (A1A1A2A2))”
on page 2–78
.
In OC-12 and OC-48 configurations, you can configure the word aligner
to either align to a 16-bit A1A2 pattern or a 32-bit A1A1A2A2 pattern.
This is controlled by the
rx_a1a2size
input port to the transceiver. A
Transmitter Digital Logic
Receiver Digital Logic
Analog Receiver and
Transmitter Logic
FPGA
Logic
Array
TX Phase
Compensation
FIFO
RX Phase
Compen-
sation
FIFO
Byte
Serializer
8B/10B
Encoder
Serializer
Clock
Recovery
Unit
Word
Aligner
Deskew
FIFO
8B/10B
Decoder
Byte
De-
serializer
Byte
Ordering
Rate
Match
FIFO
De-
serializer
32
32
32
32
32
16
16
16
16
16