HC4GX15 Datasheet, PDF (436/668 Pages) Altera Corporation – HardCopy IV Device Handbook

1–172
Chapter 1: HardCopy IV GX Transceiver Architecture
Functional Modes
SONET/SDH OC-96 Datapath
Figure 1–142 shows the transceiver datapath when configured in SONET/SDH OC-96
mode.
Figure 1–142. SONET/SDH OC-96 Datapath
Core
Fabric
TX Phase
Compensation
FIFO
wrclk
rdclk
tx_coreclk
tx_clkout
Core Fabric-Transmitter
Interface Clock
Transmitter Channel PCS
Byte
Serializer
wrclk
rdclk
/2
Low-Speed Parallel Clock
Transmitter Channel PMA
Serializer
Local
Clock
Divider
High-Speed
Serial Clock
Receiver Channel PCS Receiver Channel PMA
RX Phase
Compensation
FIFO
Byte De-
serializer
Word
Aligner
De-
Serializer
CDR
rx_coreclk
rx_clkout
Core Fabric-Receiver
Interface Clock
/2
Parallel
Recovered Clock
SONET/SDH Transmission Bit Order
Unlike Ethernet, where the LSB of the parallel data byte is transferred first,
SONET/SDH requires the MSB to be transferred first and the LSB to be transferred
last. To facilitate the MSB-to-LSB transfer, you must enable the following options in
the ALTGX MegaWizard Plug-In Manager:
■ Flip transmitter input data bits
■ Flip receiver output data bits
Depending on whether data bytes are transferred MSB-to-LSB or LSB-to-MSB, you
must select the appropriate word aligner settings in the ALTGX MegaWizard Plug-In
Manager. Table 1–48 on page 1–173 lists the correct word aligner settings for each bit
transmission order.
Word Alignment
The word aligner in SONET/SDH OC-12, OC-48, and OC-96 modes is configured in
manual alignment mode, as described in “Word Aligner in Single-Width Mode with
8-Bit PMA-PCS Interface Modes” on page 1–74.
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 low level on the rx_a1a2size port
configures the word aligner to align to a 16-bit A1A2 pattern; a high level on the
rx_a1a2size port configures the word aligner to align to a 32-bit A1A1A2A2
pattern.
In OC-96 configuration, the word aligner is only allowed to align to a A1A1A2A2
pattern, so input port rx_ala2size is unavailable. Barring this difference, the OC-96
word alignment operation is similar to that of the OC-12 and OC-48 configurations.
HardCopy IV Device Handbook Volume 3
© June 2009 Altera Corporation