BT8376EPF datasheet(49/323 Pages) CONEXANT

49 / 323 page

Bt8370/8375/8376

2.0 Circuit Description

Fully Integrated T1/E1 Framer and Line Interface

2.4 Receiver

N8370DSE

Conexant

2-21

2.4.7 Receive Framing

Two framers are in the receive data stream: an offline framer and an online frame

status monitor. The offline framer recovers receive frame alignment; the online

framer monitors frame alignment patterns and recovers multiframe alignment in

E1 modes. Frame and multiframe synchronization criteria used by the framers

and monitoring criteria of the online framer are selected in RFRAME[3:0] of the

Primary Control register [CR0; addr 001].

Receive frame synchronization is initiated by the online framer’s activation of

the Receive Loss of Frame (RLOF) status bit in the Alarm 1 Status register

[ALM1; addr 047]. The RLOF criteria is set in the RLOFA, RLOFB, RLOFC,

and RLOFD bits of the Receiver Configuration register [RCR01; addr 040]. The

online framer supports the following LOF criteria for T1: 2 out of 4, 2 out of 5,

and 2 out of 6. For E1, the online framer supports 3 out of 3, with or without 915

out of 1000 CRC errors.

Once RLOF is asserted, the offline framer automatically starts searching the

receive data stream for a new frame alignment, provided that receive framing is

enabled [RABORT; addr 040]. If receive framing is disabled, the offline framer

does not automatically search for the frame alignment, but waits for a reframe

command [RFORCE; addr 040] to start a frame alignment search. If RLOF

integration is enabled [RLOF_INTEG; addr 045] the RLOF status [ALM1;

addr 047] and RLOF interrupt status [ISR7; addr 004] is integrated for 2.0 to

2.5 seconds.

BT8376EPF Datasheet(PDF) 49 Page - Synaptics Incorporated.