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RELEASED
PM73122 AAL1GATOR-32
DATASHEET
PMC-1981419
ISSUE 7
32 LINK CES/DBCES AAL1 SAR PROCESSOR
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
83
Figure 26 CAS Idle Detection Interrupt Word
8
Status
Channel
Unused
15
2
1
0
8
7
12
13
Line
11.2.1.1.4.2 Processor Controlled Idle Detection
In Processor controlled idle detection mode, it is the responsibility of the
processor to add or drop channels. This mode is used in conjunction with
common channel signaling (CCS) or if the processor wants to make its own
determination of channel activity based on the CAS bits.
During the processor controlled idle detection, a word is written to the Transmit
Idle Interrupt FIFO every time the value of the CAS nibble changes and then
remains stable for one additional multiframe. TIDLE_FIFO_EMPB is set as long
as this FIFO contains any unread entries, which will result in a maskable
interrupt. The structure of the word contained in the FIFO is shown in Figure 27.
The first eight bits indicate the channel, which encountered a change in the value
of CAS. The next four bits indicate the RX CAS value and the final four bits
indicate the TX CAS value.
TX refers to the CAS incoming on the TDM interface (SBI Drop bus, H-MVIP
RL_SIG or direct low speed mode RL_SIG), and RX refers to CAS incoming in
ATM cells at the UTOPIA Cell Sink interface.
Based on these new CAS values the processor can make a determination if the
channel should be marked as active or idle. The CAS values are de-bounced
internally one time, and any additional debounce must be done external to the
chip.
Figure 27 Processor Controlled Idle Detection Interrupt Word
Channel
7
0
15
8
TX CAS
3
4
RX CAS
12
13
Line
The processor will also be able to mask out portions of the CAS and therefore
receive interrupts only when particular bits of the CAS change. Figure 28 shows
the structure of AUTO_CONFIG_n field in the CAS/Pattern Matching
Configuration Table. The lower byte is reserved and is used in detecting