PM8610-BIAP PMC [PMC-Sierra, Inc], PM8610-BIAP Datasheet - Page 80

• Manufacturer Part Number: PM8610-BIAP
• Description: SBS Telecom Standard Product Data Sheet Preliminary
• Manufacturer: PMC [PMC-Sierra, Inc]

10.15 Receive 8B/10B Decoders
10.15.1
10.15.2
10.15.3
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-2000168, Issue 3
The Receive 8B/10B serial SBI336S Bus decoders, RW8D and RP8D, frame to the receive
stream to find 8B/10B character boundaries. It also contains a FIFO to bridge between the timing
domain of the receive LVDS links and the system clock timing domain. The RW8D block
performs framing and elastic store functions on data retrieved from the working receive LVDS
link, RPWRK/RNWRK. The RP8D block processes data on the protect receive LVDS link,
RPPROT/RNPROT.
The FIFO buffer sub-block provides isolation between the timing domain of the associated
receive LVDS link and that of the system clock, SYSCLK. The FIFO also provides a retiming
function to allow individual links in a multi-SBS system to have varying interconnect delay. This
eases timing distribution and synchronization in large systems. Data with arbitrary alignment to
8B/10B characters are written into a 10-bit by 24-word deep FIFO at the link clock rate. Data is
read from the FIFO at every SYSCLK cycle.
The alignment functionality preformed by each receiver can be broken down into two parts,
character alignment and frame alignment. Character alignment finds the 8B/10B character
boundary in the arbitrarily aligned incoming data. Frame alignment finds SBI336S or
TelecomBus frame and multiframe boundaries within the Serial link.
The character and frame alignment are expected to be robust enough for operation over a cabled
interconnect.
Character alignment locates character boundaries in the incoming 8B/10B data stream. The
character alignment algorithm may be in one of two states, in-character-alignment state and out-
of-character-alignment state. The two states of the character alignment algorithm is shown in
Figure 9.
When the character alignment state machine is in the out-of-character-alignment state, it
maintains the current alignment, while searching for a C1FP character. If it finds the C1FP
character it will re-align to the C1FP character and move to the in-character-alignment state. The
C1FP character is found by searching for the 8B/10B C1FP character, K28.5+ or K28.5-,
simultaneously in ten possible bit locations. While in the in-character-alignment state, the state
machine monitors LCVs. If 5 or more LCVs are detected within a 15 character window the
character alignment state machine transitions to out-of-character-alignment state. The special
characters listed in Table 21 and Table 22 are ignored for LCV purposes. Upon return to in-
character-alignment state the LCV count is cleared.
FIFO Buffer
Serial SBI336S and TelecomBus Alignment
Character Alignment Block
SBS Telecom Standard Product Data Sheet
Preliminary
80