BT8376EPF datasheet(78/323 Pages) CONEXANT

78 / 323 page

2.0 Circuit Description

Bt8370/8375/8376

2.7 Transmit System Bus

Fully Integrated T1/E1 Framer and Line Interface

2-50

Conexant

N8370DSE

2.7.4 Transmit Framing

The transmit data stream has two framing functions: offline framer and an online

framer. Figure 2-27 illustrates these functions. The offline framer recovers the

transmit frame alignment (TFSYNC). The online framer monitors the frame

alignment found by the offline framer and recovers multiframe alignment

(TMSYNC).

Transmit frame resynchronization is initiated by activating the Transmit Loss

of Frame (TLOF) status bit in Alarm 2 status [ALM2; addr 048] register by the

online framer. The TLOF criteria is set in the TLOFA, TLOFB, and TLOFC bits

of the Transmitter Configuration register [TCR1; addr 071]. The online framer

supports the following LOF criteria for T1: 2 frame bit errors out of 4; 2 out of 5;

or 2 out of 6. For E1, it supports 3 out of 3.

When TLOF is asserted, the offline framer searches the transmit data stream

for a new frame alignment, provided transmit framing is enabled [TABORT; addr

071]. If embedded framing is enabled [EMBED; addr 0D0], the offline framer

examines the TSLIP buffer output, TNRZ, for transmit frame alignment. If

embedded framing is disabled, the offline framer examines the slip buffer input

(TPCMI) for transmit frame alignment. This case (EMBED = 0) is only applicable

if TPCMI is configured to operate at the line rate: 2,048 kbps E1, or 1,544 kbps

T1. If transmit framing is disabled, the offline framer waits for a reframe command

[TFORCE; addr 071] before beginning frame alignment search.

Figure 2-27. Transmit Framing and Timebase Alignment Options

NOTE(S):

1. EMBED located in SBI_CR (addr 0D0).

2. TSB_ALIGN and TX_ALIGN located in TSB_CR (addr 0D4).

3. EMBED = 0 is only applicable if TPCMI is operating at the line rate.

TPCMI

Offline

Framer

Pass

TSLIP

Buffer

FSYNC MSYNC

TSB Timebase

TSB

Offset

TFSYNCI

TMSYNCI

TMSYNCO

TFSYNCO

A TSB Aligns to TPCMI (EMBED = 0)

B TSB Aligns to TX (TSB_ALIGN = 1)

TX Aligns to TNRZ (EMBED = 1)

TX Aligns to TSB (TX_ALIGN = 1)

TPHASE

Recenter

(TUSLIP)

CAS

Online

MFAS

Online

TNRZ

TX Timebase

FSYNC

MSYNC

FAS

CAS

(EMBED = 1)

BT8376EPF Datasheet(PDF) 78 Page - Synaptics Incorporated.

BT8376EPF Datasheet(HTML) 78 Page - Synaptics Incorporated.

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL