TTSV02622V2-DB AGERE [Agere Systems], TTSV02622V2-DB Datasheet - Page 30

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

Data Sheet
TTSV02622 STS-24 Backplane Transceiver
June 2003
Receiver Block
(continued)
Pointer Mover Subblock (Backplane to Line)
(continued)
NORM State. This state will begin whenever two consecutive NORM pointers are received. If two consecutive
NORM pointers are received, such that both differ from the current offset, then the current offset will be reset to the
last received NORM pointer. When the pointer interpreter changes its offset, it causes the pointer generator to
receive a J1 value in a new position. When the pointer generator gets an unexpected J1, it resets its offset value to
the new location and declares an NDF.
Note: The interpreter is only looking for two consecutive pointers that are different from the current value. These
two consecutive NORM pointers do not have to have the same value.
For example; if the current pointer is 10 and you receive a NORM pointer with offset of 15 and a second NORM
pointer with offset of 25, then the interpreter will change the current pointer to be 25.
CONC State. The receipt of two consecutive CONC pointers causes this state to be entered. Once in this state, off-
set values from the head of the concatenation chain are used to determine the location of the STS SPE for each
STS in the chain.
AIS State. Two consecutive AIS pointers cause this state to occur. Any two consecutive normal or concatenation
pointers will end this state. This state will cause the data leaving the pointer generator to be overwritten with 0xFF.
NORM
2 x CONC
CONC
AIS
2 x AIS
Figure 10. Pointer Mover State Machine
Pointer Generator
The pointer generator simply maps the corresponding bytes into their appropriate location in the outgoing byte
stream. The generator also creates offset pointers based on the location of the J1 byte as indicated by the pointer
interpreter. The generator will signal NDFs when the interpreter signals that it is coming out of AIS state. The gen-
erator resets the pointer value and generates NDF every time a byte marked J1 is read from the elastic store that
doesn’t match the previous offset.
Increments and decrements signals from the pointer interpreter are latched once per frame on either the F1 or E2
byte times (depending on collisions), this ensures constant values during the H1 through H3 times. The choice of
which byte time to do the latching on is made when the relative frame phases (i.e., received and system) is deter-
mined. This latch point will then be stable, unless the relative framing changes and the received H byte times col-
lide with the system F1 or E2 times, in which case the latch point would be switched to the collision-free byte time.
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Agere Systems Inc.