DS2155 datasheet(83/238 Pages) DALLAS

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DS2155

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16.

SIGNALING OPERATION

There are two methods to access receive signaling data and provide transmit signaling data, processor-

based (software-based) or hardware-based. Processor-based refers to access through the transmit and

receive signaling registers RS1–RS16 and TS1–TS16. Hardware-based refers to the TSIG and RSIG pins.

Both methods can be used simultaneously.

16.1 Receive Signaling

Figure 16-1. Simplified Diagram of Receive Signaling Path

16.1.1 Processor-Based Signaling

The robbed-bit signaling (T1) or TS16 CAS signaling (E1) is sampled in the receive data stream and

copied into the receive signaling registers, RS1–RS16. In T1 mode, only RS1–RS12 are used. The

signaling information in these registers is always updated on multiframe boundaries. This function is

always enabled.

16.1.1.1 Change-of-State

To avoid constant monitoring of the receive signaling registers, the DS2155 can be programmed to alert

the host when any specific channel or channels undergo a change of their signaling state.

RSCSE1–RSCSE4 for E1 and RSCSE1–RSCSE3 for T1 are used to select which channels can cause a

change-of-state indication. The change-of-state is indicated in status register 5 (SR1.5). If signaling

integration (CCR1.5) is enabled, then the new signaling state must be constant for three multiframes

before a change-of-state is indicated. The user can enable the INT pin to toggle low upon detection of a

change in signaling by setting the IMR1.5 bit. The signaling integration mode is global and cannot be

enabled on a channel-by-channel basis.

The user can identity which channels have undergone a signaling change-of-state by reading the

RSINFO1–RSINFO4 registers. The information from these registers inform the user which RSx register

to read for the new signaling data. All changes are indicated in the RSINFO1–RSINFO4 registers

regardless of the RSCSE1–RSCSE4 registers.

RECEIVE SIGNALING

REGISTERS

CHANGE-OF-STATE

INDICATION

REGISTERS

SIGNALING

BUFFERS

ALL-ONES

REINSERTION

CONTROL

RSER

RSYNC

RSIG

T1/E1 DATA STREAM

PER-CHANNEL

CONTROL

SIGNALING

EXTRACTION

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