2–180
Altera Corporation
Stratix II GX Device Handbook, Volume 2
October 2007
Native Modes
Synchronization (Word Aligner)
Synchronization is required in GIGE mode to align the byte boundary of
the receiver to the byte boundary of the transmitter, because the
Stratix II GX transceiver block uses a non-source-synchronous serial
stream. To correctly align the byte boundary at the receiver, a unique
synchronization pattern must be received that does not occur between
any Dx.y and/or Kx.y code combinations. A /K28.5/ 10-bit comma is
used for this purpose.
Synchronization is achieved when the receiver sees three consecutive
ordered sets. An ordered set defined for synchronization is a /K28.5/
comma followed by any odd number of valid /Dx.y/ code (/Dx.y/
denotes any valid data code group). Although you can have a number of
synchronization patterns based on the synchronization rule, three
/K28.5/ followed by one /Dx.y/ code is the fastest synchronization
pattern.
Once the synchronization is achieved, the state machine considers a bad
code group received (
cgbad
) if one of the following two conditions are
met:
■
The incoming code group has a disparity error or a code group
violation
■
The incoming code group is a comma character and
rx_even=true
.
This condition occurs when an even number of non-comma code
groups are received between two comma code groups.
/C2/
Configuration 2
4
/K28.5/D2.2/
Config_Reg
(1)
/I/
IDLE
Correcting /I1/, Preserving /I2/
/I1/
IDLE 1
2
/K28.5/D5.6
/I2/
IDLE 2
2
/K28.5/D16.2
Encapsulation
/R/
Carrier_Extend
1
/K23.7/
/S/
Start_of_Packet
1
/K27.7/
/T/
End_of_Packet
1
/K29.7/
/V/
Error_Propagation
1
/K30.7/
Note to
Table 2–42
:
(1)
Two data code groups representing the
Config_Reg
value.
Table 2–42. GIGE Code Groups (Part 2 of 2)
Code
Ordered Set
Number of
Code
Groups
Encoding
Содержание Stratix II GX
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