ORT82G5-1BM680C LATTICE [Lattice Semiconductor], ORT82G5-1BM680C Datasheet - Page 25

• Manufacturer Part Number: ORT82G5-1BM680C
• Description: 0.6 to 3.7 Gbps XAUI and FC FPSCs
• Manufacturer: LATTICE [Lattice Semiconductor]

Lattice Semiconductor
Figure 9. Fibre Channel Link State Machine State Diagram
XAUI Link Synchronization Function
For each lane, the receive section of the XAUI link state machine incorporates a synchronization state machine that
monitors the status of the 10-bit alignment. A 10-bit alignment is done in the SERDES based on a comma charac-
ter such as K28.5. A comma (0011111 or its complement 1100000) is a unique pattern in the 10-bit space that can-
not appear across the boundary between any two valid 10-bit code-groups. This property makes the comma useful
for delimiting code-groups in a serial stream.This mechanism incorporates a hysteresis to prevent false synchroni-
zation and loss of synchronization due to infrequent bit errors. For each lane, the sync_complete signal is disabled
until the lane achieves synchronization. The synchronization state diagram is shown in Figure 10. This state
machine is modeled after draft IEEE 802.3ae, version 2.1 but will also operate with version 4.1 implementations.
Table 4 and Table 5 describe the state variables used in Figure 10. The XAUI state machine does not have any
control over the SERDES byte aligner. It is the user’s responsibility to control the byte aligner through software
access of register map addresses 30800 and 30900.
Note that it takes four idle ordered sets (e.g. K28.5, Dxx.y, Dxx.y, Dxx.y) to bring the state machine from a
loss_of_sync to a synch_acq’d_1 state. When back-to-back commas are used instead, it takes a total of five com-
mas to achieve the same result as with idle ordered sets.
Table 4. XAUI Link Synchronization State Diagram – Functions
sync_complete
cg_comma
cg_good
cg_bad
no_comma
Function
POWERUP_RESET
LSM_ENABLE
+
RST
Indication that alignment code-group alignment has been established at the boundary indicated by the
most recently received comma.
Indication that a valid code-group, with correct running disparity, containing a comma has been received.
Indication that a valid code-group with the correct running disparity has been received.
Indication that an invalid code-group has been received.
Indication that comma timer has expired. The timer is initialized upon receipt of a comma.
CV
CV
LAST ORDERED SET RECEIVED:
VW: VALID WORD (A 4 CHARACTER BASED WORD HAVING NO CODE VIOLATION) WITH AT LEAST
2VW: SECOND VALID WORD AFTER A CODE VIOLATION
OS: IDLE ORDERED SET (A 4 CHARACTER BASED WORD HAVING COMMA AS THE 1ST CHARACTER)
CV: CODE VIOLATION (RUNNING DISPARITY BASED ON ILLEGAL COMMA POSITION)
1VW: FIRST VALID WORD AFTER A CODE VIOLATION
TWO PRECEEDING VALID WORDS
a
h
g
f
OS
OS
OS
VW
OS
LINK SYNCHRONIZATION ACHIEVED (WDSYNC = 1)
2 VW
CV
LOSS OF SYNCHRONIZATION (WDSYNC_XX = 0)
b
1VW
25
2 VW
CV
ORCA ORT42G5 and ORT82G5 Data Sheet
Description
c
1VW
2 VW
CV
d
e
CV
1VW
LOS = 1