Altera Corporation
2–171
October 2007
Stratix II GX Device Handbook, Volume 2
Stratix II GX Transceiver Architecture Overview
The PCS code-groups are sent via PCS ordered sets. PCS ordered sets
consist of combinations of special and data code groups defined as a
column of code groups. These ordered sets are composed of four code
groups beginning in lane 0.
Table 2–39
lists the defined idle ordered sets
(||I||) that are used for the self-managed properties of XAUI.
Synchronization ||K|| (Word Aligner)
XAUI uses an embedded clocking scheme that re-times the data that can
potentially alter the code-group boundary. The boundaries of the code
groups are re-aligned through a synchronization process specified in
clause 48 of the IEEE P802.3ae standard, which states that
synchronization is achieved upon the reception of four /K28.5/ commas.
Each comma can be followed by any number of valid code groups.
Invalid code groups are not allowed during the synchronization stage.
When you configure Stratix II GX devices to the XAUI protocol, the
built-in pattern detector, word aligner, and XAUI state machines adhere
to the PCS synchronization specification. After all the conditions for
synchronization have been met, the
rx_syncstatus
signal is asserted
and only de-asserts if synchronization is lost.
Table 2–39. Defined Idle Ordered Set
Code
Ordered Set
Number of
Code Groups
Encoding
||I||
Idle
Substitute for XGMII Idle
||K||
Synchronization
column
4
/K28.5/K28.5/K28.5/K28.5
||R||
Skip column
4
/K28.0/K28.0/K28.0/K28.0
||A||
Align column
4
/K28.3/K28.3/K28.3/K28.3