TTSV02622V2-DB AGERE [Agere Systems], TTSV02622V2-DB Datasheet - Page 25

• Manufacturer Part Number: TTSV02622V2-DB
• Description: STS-24 Backplane Transceiver
• Manufacturer: AGERE [Agere Systems]

June 2003
Agere Systems Inc.
Receiver Block
Framer Subblock (Backplane to Line)
Framer State Machine
Figure 9 shows the state machine that controls the framer. Since the TTSV02622 is intended for use between
ASICs via a backplane, there is only one errored frame state; thus, after two transitions are missed, the state
machine goes into the OOF state and there is no SEF or LOF indication.
OOF State. In this state, the A1 pattern is searched for on every clock cycle.
A second stage of comparison is implemented to locate the A1/A2 transition. When the A1/A2 transition is found,
the following occurs:
Frame Confirm. In this state, the A1/A2 transition is only compared for at the appropriate location, i.e., beginning
at the twelfth A1 location. This location is determined from the row, column, and STS counters which were set at
the transition from OOF to frame confirm. If at this time the comparison fails, the state machine reverts to the OOF
state. If the comparison passes, the next state will be In frame.
In Frame. This state is similar to the frame confirm state except that if the comparison at the A1/A2 time is incor-
rect, the next state will be the errored frame state. If the comparison is correct, the next state will be in frame.
Errored Frame. Once the errored frame state has been reached, if the next comparison is incorrect, the next state
will be OOF. Otherwise, if correct, the next state will be in frame. This state will generate an error interrupt to the
micro.
The state machine moves from the OOF state to the frame confirm state.
The A1offset for the byte start location is locked.
The row, column, and STS counters are set.
(continued)
(continued)
TTSV02622 STS-24 Backplane Transceiver
25