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PM73121AAL1gator II
PMC-Sierra, Inc.
L
PMC-980620
,VVXH
AAL1 SAR Processor
Data Sheet
35235,(7$5<$1'&21),'(17,$/7230&6,(55$,1&$1')25,76&86720(56,17(51$/86(
The adaptive clocking mechanism shares the SRTS port with the SRTS mechanism. It operates
according to the following psuedocode:
If an SRTS difference value is ready, it is played out with SRTS_STRB asserted and
ADAP_STRB deasserted. The SRTS values have higher priority than the adaptive clock
values.
Else if a channel pair is being serviced, start a state machine to play out the channel status,
as shown in
Table 3 on page 72
, asserting ADAP_STRB as each state is played out.
Else if a cell is received and a valid frame difference can be computed, start a state
machine to play out the frame difference and queue number, as shown in
Table 4 on
page 72
, asserting ADAP_STRB as each state is played out.
The playout of the channel status may interrupt the playout of the frame difference at any point.
Table 3.
Channel Status
SRTS_LINE(3:0)
Value
SRTS_DOUT(3:0) Value
3
2
1
0
15
0
line(2)
line(1)
line(0)
14
channel(4)
channel(3)
channel(2)
channel(1)
13
underrun_h
resume_h
underrun_1
resume_1
NOTES:
The underrun bit goes high when underrun occurs and will stay high until the underrun
condition is cleared.
Resume goes high when the underrun condition is cleared and goes low when the read
pointer equals the underrun_end pointer.
The status is played out once for every 16 receive line clocks.
The channel values (4:1) identify 16 channel pairs. The odd and even numbered channels of
each pair are carried by the high and low bits, respectively.
For UDF-ML mode, the values in channel (4:1) and underrun_l can be ignored. Line (2:0)
indicate the line number and underrun_h represents the queue status.
Table 4.
Frame Difference
SRTS_LINE(3:0)
Value
SRTS_DOUT(3:0) Value
3
2
1
0
5
cell_vci(7)
cell_vci(6)
cell_vci(5)
cell_vci(4)
4
cell_vci(3)
cell_vci(2)
cell_vci(1)
cell_vci(0)