XRT7250 datasheet(189/463 Pages) EXAR

189 / 463 page

XRT7250

DS3/E3 FRAMER IC

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REV. 1.1.1

170

NOTE: This bit is ignored when either the Transmit Yellow

Alarm, Tx AIS, Tx IDLE, or TxLOS bit is set.

4.2.4.2.1.3

Transmit Idle Pattern - Bit 5

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

Idle pattern to the remote terminal equipment upon

software control. Table 29 relates the contents of this

bit field to the Transmit DS3 Framer's action.

NOTE: This bit is ignored when either the Tx AIS or the Tx

LOS bit is set.

4.2.4.2.1.4

Transmit AIS Pattern - Bit 4

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

AIS pattern to the remote terminal equipment, upon

software control. Table 30 relates the contents of this

bit field to the Transmit DS3 Framer block's action.

TABLE 28: THE RELATIONSHIP BETWEEN THE CONTENTS OF BIT 6 (TX X-BITS) WITHIN THE TX DS3 CONFIGURATION

BIT 6TRANSMIT DS3 FRAMER'S ACTION

Normal Operation:

The X-bits are generated by the Transmit DS3 Framer block based upon Receiving Conditions (as detected

by the Receive Section of the Framer chip).

Set X-bits to 1:

The Transmit DS3 Framer will overwrite the X-bits by setting them to 1. Payload information is not modified

and is transmitted as normal.

TABLE 29: THE RELATIONSHIP BETWEEN THE CONTENTS OF BIT 5 (TX IDLE) WITHIN THE TX DS3 CONFIGURATION

BIT 5TRANSMIT DS3 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 Idle Condition Pattern:

When this command is invoked, the Transmit DS3 Framer will do the following:

• Set the X-bits to 1

• Set the CP-Bits (F-Frame #3) to 0

• Generate Valid M, F, and P bits

Overwrite the data in the DS3 payload with a repeating 1100... pattern.

XRT7250 Datasheet(PDF) 189 Page - Exar Corporation