PM5381-BI PMC-Sierra, Inc., PM5381-BI Datasheet - Page 513

• Manufacturer Part Number: PM5381-BI
• Description: ATM UNI, Single Channel ATM PHY Interface for 2488.32Mbps
• Manufacturer: PMC-Sierra, Inc.

13.1.5
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-2000489, Issue 4
The R8TD character alignment block uses the K28.5 control character (Comma control / transport
frame alignment) to determine 8B/10B character alignment in the incoming stream. When the
R8TD character alignment state machine is in the out-of-character-alignment state, it searches for
the K28.5 character in all positions of the incoming stream. Upon detecting the K28.5 character,
the R8TD will align its internal character boundary, the character alignment state machine will
transition to the in-character-alignment state and cease searching for subsequent K28.5 characters.
The character alignment block also monitors for line-code violations (LCV) which are
accumulated in an internal register. If 5 or more LCVs are detected within a window of 15
characters, the R8TD will enter the out-of-character-alignment state and begin searching for the
K28.5 character afresh.
When operating in FIFO mode, aligned characters are written into a 24-character FIFO that
isolates the incoming timing domain from the outgoing timing domain and provides a means of
synchronizing multiple R8TDs outputs. Otherwise, the FIFO is bypassed.
In order to allow synchronization with other R8TDs that may have slightly different frame
alignment and to allow for frame re-alignment, the R8TD frame alignment block monitors the
character aligned data stream for the K28.5. An internal frame counter is maintained based on
this character. If the K28.5 is found out of place three times, then the frame alignment moves to
the out-of-frame-alignment state. When in the out-of-frame-alignment state, the first K28.5 will
be written to the 0 position of the FIFO. The read pointer is then set by the APSIFP signal to
synchronize the output of the K28.5 characters which ensures that signals leaving the multiple
R8TDs will have the same alignment.
The R8TD decodes 8B/10B control characters associated with specific SONET/SDH byte
positions in an extended TelecomBus stream. In order to identify more SONET/SDH bytes than
the 12 control characters available in the standard set, those control characters with balanced line
codes for both positive and negative running disparity (K28.0, K28.4, K38.7, K23.7, K27.7,
K29.7 and K30.7) are treated specially, where the positive and negative disparity codes are each
associated with a different SONET/SDH byte. The reception of these line-codes will not be
considered LCVs due to a mismatch with the running disparity.
The R8TD provides a diagnostic loopback port where the outgoing stream from an associated
Transmit 8B/10B Encoder block (T8TE) can be processed in place of the incoming stream.
Transmit 8B/10B TelecomBus Encoder (T8TE)
The T8TE encodes a TelecomBus data stream and encodes it into an extended 8B/10B format for
transmission on the serial LVDS links. The T8TE encodes TelecomBus control signals such as
transport frame and payload boundaries, pointer justification events and alarm conditions into
three levels of extended set of 8B/10B characters as well as performing the IEEE mode
conversion on data. In order to identify more TelecomBus bytes and events than the 12 control
characters available in the standard set, those control characters with balanced line codes for both
positive and negative running disparity (K28.0, K28.4, K28.5, k28.6, k28.7, K23.7, K27.7, K29.7
and K30.7) are treated specially. The positive and negative disparity codes are each associated of
a different SONET/SDH byte or event.
S/UNI-2488 Telecom Standard Product Datasheet
Released
513