XRT7250 datasheet(271/463 Pages) EXAR

271 / 463 page

XRT7250

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DS3/E3 FRAMER IC

REV. 1.1.1

252

How to configure the XRT7250 into Mode 6

1. Set the NibInt input pin "High".

2. Set the TimRefSel[1:0] bit-fields (within the

Framer Operating Mode Register) to "1X" as illus-

trated below.

3. Interface the XRT7250, to the Terminal Equip-

ment, as illustrated in Figure 110.

5.2.2

The Transmit Overhead Data Input Inter-

face

Figure 112 presents a simple illustration of the Trans-

mit Overhead Data Input Interface block within the

XRT7250.

FIGURE 111. BEHAVIOR OF THE TERMINAL INTERFACE SIGNALS BETWEEN THE XRT7250 AND THE TERMINAL

EQUIPMENT (E3 MODE 6 OPERATION)

Terminal Equipment Signals

TxInClk

Tx_Start_of_Frame

E3_Nib_Clock_In

E3_Data_Out[3:0]

Payload Nibble [380]

Overhead Nibble [0]

XRT7250 Transmit Payload Data I/F Signals

E3 Frame Number N

E3 Frame Number N + 1

Note: TxNibFrame pulses high to denote

E3 Frame Boundary.

TxInClk

TxNibFrame

TxNibClk

TxNib[3:0]

Nibble [380]

Overhead Nibble [0]

E3_Overhead_Ind

TxOH_Ind

TxOH_Ind pulses high for 3 Nibble periods

FRAMER OPERATING MODE REGISTER (ADDRESS = 0X00)

BIT 7BIT 6BIT 5BIT 4BIT 3BIT2

BIT 1

BIT 0

Local

Loopback

DS3/E3*

Internal

LOS

Enable

RESET

Interrupt

Enable

Reset

Frame

Format

TimRefSel[1:0]

R/W

101

XRT7250 Datasheet(PDF) 271 Page - Exar Corporation

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