RELEASED
PM73123 AAL1GATOR-8
DATASHEET
PMC-2000097
ISSUE 2
8 LINK CES/DBCES AAL1 SAR
Figure 28 Pattern Match Idle Detection Register Structure
15
8
7
0
PATTERN_MASK
IDLE_PATTERN
During pattern match idle detection, a word is written to TIDLE_FIFO every time
the status changes from active->idle or idle->active. An interrupt is generated as
long as this FIFO contains any unread entries. The structure of the word
contained in the FIFO is shown in Figure 29. The upper eight bits indicate the
channel that encountered the status change and bit 0 indicates the status of the
channel (Active =1; Idle = 0). The processor accesses the FIFO by reading the
Status Interrupt register, which will contain the top element of the FIFO.
Figure 29 Pattern Match Idle Detection Interrupt Word
1
0
15
13 12
9
8
2
Line
Channel
Unused
Status
9.2.1.2 Cell Service Decision (CSD) Circuit
The CSD circuit determines which cells are to be sent and when. It determines
this by implementing Transmit Calendar bit tables and Active/Idle bit tables.
When the TALP builds a cell, the CSD circuit performs a complex calculation
using credits to determine the frame in which the next cell from that queue
should be sent. The CSD circuit schedules a cell only when a cell is built by the
TALP. If SUPPRESS_TRANSMISSION bit in the TX_CONFIG word is set, then
the cell is scheduled, however, the cell is not transmitted.
In non-DBCES mode, a queue can be placed in idle detection mode by setting
the IDLE_DET_ENABLE in the TRANSMIT_CONFIG word within the queue
table. When a queue is set for idle detection mode and all the channels on a
given queue are inactive, cells are scheduled, but no cells are actually sent. This
mode also requires that one of the idle detection methods is enabled for all the
channels of the given queue. This can be done by programming the A1SP Idle
Detection Configuration Table.
The following steps (as well as Figure 30 on page 91) describe how the CSD
circuit schedules cells for the TALP to build.
PMC-SIERRA, INC. PROPRIETARY AND CONFIDENTIAL
89
PMC [ PMC-SIERRA, INC ]
