XRT7250 datasheet(394/463 Pages) EXAR

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XRT7250

DS3/E3 FRAMER IC

REV. 1.1.1

375

• Generate and transmit a desired value for the

FEBE (Far-End-Block Error) bit, within the MA byte.

The procedure and results of generating any of these

alarm conditions is presented below.

The user can exercise each of these options by writ-

ing the appropriate data to the Tx E3 Configuration

ister is presented below.

Bit-field 2 through 0 permit the user to transmit vari-

ous alarm conditions to the remote terminal equip-

ment. The role/function of each of these three bit-

fields within the register, are discussed below.

6.2.4.2.1.1

Tx AIS Enable - Bit 2

This read/write bit field permits the user to force the

transmission of an AIS (Alarm Indication Signal) pat-

tern to the remote terminal equipment via software

control. If the user opts to transmit an AIS pattern,

then the Transmit Section of the Framer IC will begin

to transmit an unframed all ones pattern to the re-

mote terminal equipment. Table 78 presents the rela-

tionship between the contents of this bit-field, and the

resulting Framer action.

NOTE: This bit is ignored whenever the TxLOS bit-field is

set.

6.2.4.2.1.2

Transmit LOS Enable - Bit 1

This read/write bit field allows the user to transmit an

LOS (Loss of Signal) pattern to the remote terminal,

upon software control. Table 79 relates the contents

of this bit field to the Transmit E3 Framer block's ac-

tion.

TXE3 CONFIGURATION REGISTER (ADDRESS = 0X30)

BIT 7BIT 6BIT 5BIT 4BIT 3BIT 2BIT 1BIT 0

Not Used

TxDL

in NR

Not Used

TxAIS

Enable

TxLOS

Enable

TxMARx

R/W

0000

000

TABLE 78: THE RELATIONSHIP BETWEEN THE CONTENTS OF BIT 2 (TX AIS ENABLE) WITHIN THE TX E3

CONFIGURATION REGISTER, AND THE RESULTING TRANSMIT E3 FRAMER BLOCK'S ACTION

BIT 2TRANSMIT E3 FRAMER'S ACTION

Normal Operation:

The Transmit Section of the XRT7250 Framer IC will transmit E3 traffic based upon data that it accepts via the

Transmit Payload Data Input Interface block, the Transmit Overhead Data Input Interface block, the Transmit

HDLC Controller block and internally generated overhead bytes.

Transmit AIS Pattern:

The Transmit E3 Framer block will overwrite the E3 traffic, within an Unframed All Ones pattern.

TABLE 79: THE RELATIONSHIP BETWEEN THE CONTENTS OF BIT 1 (TX LOS) WITHIN THE TX E3 CONFIGURATION

BIT 1TRANSMIT E3 FRAMER'S ACTION

Normal Operation:

The Overhead bits are either internally generated, or they are inserted via the Transmit Overhead Data Input

Interface or the Transmit HDLC Controller blocks. The Payload bits are received from the Transmit Payload

Data Input Interface.

Transmit LOS Pattern:

When this command is invoked the Transmit E3 Framer will do the following.

• Set all of the overhead bytes to "0" (including the FA1 and FA2 bytes)

Overwrite the E3 payload bits with an "all zeros" pattern.

XRT7250 Datasheet(PDF) 394 Page - Exar Corporation

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