
PRELIMINARY
XRT79L71
376
REV. P2.0.0
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
The Receive E3 Framer block's operation, while in the "OOF State" is a unique mix of the "Framing
Maintenance" and "Frame Acquisition" operations. In the "OOF State" the Receive E3 Framer block will exhibit
some "Frame Acquisition" operational characteristics by attempting to locate (once again) the FAS pattern.
However, the Receive E3 Framer block will also exhibit some Frame Maintenance operational behavior by still
using the most recent frame synchronization for its overhead and payload byte processing.
What happens when the Receive E3 Framer block transitions into the "OOF" State?
As the Receive E3 Framer block transitions from the "In-Frame" into the "OOF State", it will inform the
Microprocessor of this fact by doing all of the following.
Declaring the "OOF Defect Condition"
The Receive E3 Framer block will indicate that it is declaring the "OOF Defect Condition" by setting bit 5 (OOF
Defect Declared), within the "Receive E3 Configuration and Status Register # 2" to "1" as depicted below.
FIGURE 177. THE STATE MACHINE DIAGRAM FOR THE RECEIVE E3 FRAMER BLOCK'S "FRAME ACQUISITION/MAIN-
TENANCE
" ALGORITHM (WITH THE "OOF STATE" SHADED)
Receive E3 Configuration and Status Register # 2 - G.751 (Address = 0x1111)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
RxLOF
Algo
LOF
Defect
Condition
Declared
OOF
Defect
Condition
Declared
LOS
Defect
Condition
Declared
AIS
Defect
Condition
Declared
Unused
FERF/RDI
Defect
Condition
Declared
R/W
R/O
0
1
0
FAS
Pattern
Search
FAS
Pattern
Search
LOF
State
LOF
State
OOF
State
OOF
State
In Frame
State
In Frame
State
FAS
Pattern
Verification
FAS
Pattern
Verification
FAS Pattern is
detected Once
FAS Pattern is
NOT Detected
FAS Patten is verified
Three consecutive times
4 Consecutive
Invalid Frames
3 Consecutive
Valid Frames
8 or 24 frame periods of
Operating in the “OOF State”
(User Selectable)
Frame Maintenance
Mode