PM8611-BIAP PMC [PMC-Sierra, Inc], PM8611-BIAP Datasheet - Page 38

• Manufacturer Part Number: PM8611-BIAP
• Manufacturer: PMC [PMC-Sierra, Inc]

10.1.3
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-2010883, Issue 2
The SBI bus supports a synchronous SBI mode for T1 and E1 links. In this mode the DS0s or
timeslots within the T1 or E1 tributaries are fixed to the locations shown in the T1 and E1
mappings. Effectively synchronous mode locks the V5 in the octet following the V1 octet and
does not allow the tributaries to float relative to SREFCLK19.
SBI Link Rate Information
The SBI bus provides a method for carrying link rate information. This is optional on a per
channel basis. Two methods are specified, one for T1 and E1 channels and the second for DS3
and E3 channels. Link rate information is not available for TVTs. These methods use the
reference 19.44 MHz SBI clock and the IC1FP frame synchronization signal to measure channel
clock ticks and clock phase for transport across the bus.
The T1 and E1 method allows for a count of the number of T1 or E1 rising clock edges between
two IC1FP frame pulses. This count is encoded in ClkRate[1:0] to indicate that the nominal
number of clocks, one more than nominal or one less than nominal should be generated during
the IC1FP period. This method also counts the number of 19.44 MHz clock rising edges after
sampling IC1FP high to the next rising edge of the T1 or E1 clock, giving the ability to control
the phase of the generated clock. The link rate information passed across the SBI bus via the V4
octet and is shown in Table 4. Table 5 shows the encoding of the clock count, ClkRate[1:0],
passed in the link rate octet.
Table 4 T1/E1 Link Rate Information
Table 5 T1/E1 Clock Rate Encoding
C1FP
REFCLK
T1/E1 CLK
Link Rate Octet
T1/E1 Format
ClkRate[1:0]
“00” – Nominal
“01” – Fast
“1x” – Slow
T1 Clocks / 2 KHz
772
773
771
Bit #
Clock Count
7
ALM
6
0
SBSLITE™ Telecom Standard Product Data Sheet
E1 Clocks / 2 KHz
1024
1025
1023
5:4
ClkRate[1:0]
3:0
Phase[3:0]
Phase
Preliminary
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