DS26401 datasheet(71/309 Pages) DALLAS

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DS26401 Octal T1/E1/J1 Framer

8.11.5 Receive-Signaling Reinsertion at RSER

In this mode, the user provides a multiframe sync at the RSYNC pin, and the signaling data is reinserted based on

this alignment. In T1 mode, this results in two copies of the signaling data in the RSER data stream. The original

signaling data is based on the Fs/ESF frame positions and the realigned data is based on the user-supplied

multiframe sync applied at RSYNC. In voice channels, this extra copy of signaling data is of little consequence.

Reinsertion can be avoided in data channels since this feature is activated on a per-channel basis. For reinsertion,

the elastic store must be enabled, however, the backplane clock can be either 1.544MHz or 2.048MHz.

Signaling reinsertion mode is enabled on a per-channel basis by setting the receive-signaling reinsertion channel-

select bit high in the RSIx registers. The channels that are to have signaling reinserted are selected by writing to the

RSI1–RSI3 registers for T1.

8.11.6 Force Receive-Signaling All Ones

In T1 mode, the user can, on a per-channel basis, force the robbed-bit signaling bit positions to 1. This is done by

using the RSAOI registers. The user sets the channel-select bit in the RSAOI1–RSAOI3 registers to select the

channels that are to have the signaling forced to 1.

8.11.7 Receive-Signaling Freeze

The signaling data in the four-multiframe signaling buffer is frozen in a known good state upon either a loss-of-

synchronization (OOF event), carrier loss, or change-of-frame alignment. This action meets the requirements of

BellCore TR-TSY-000170 for signaling freezing. To allow this freeze action to occur, the RSFE control bit

(RSIGC.1) should be set high. The user can force a freeze by setting the RSFF control bit (RSIGC.2) high. The

RSIGF output pin provides a hardware indication that a freeze is in effect. The four-multiframe buffer provides a

three-multiframe delay in the signaling bits provided at the RSIG pin (and at the RSER pin if receive-signaling

reinsertion is enabled). When freezing is enabled (RSFE = 1), the signaling data is held in the last known good state

until the corrupting error condition subsides. When the error condition subsides, the signaling data is held in the old

state for at least an additional 9ms (or 4.5ms in D4 framing mode) before being allowed to be updated with new

signaling data.

DS26401 Datasheet(PDF) 71 Page - Dallas Semiconductor