XRT7250 datasheet(342/463 Pages) EXAR

342 / 463 page

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XRT7250

DS3/E3 FRAMER IC

REV. 1.1.1

323

Whenever the user’s system encounters the Change

in Receive LOS Condition Interrupt, then it should do

the following.

1. It should determine the current state of the LOS

condition. Recall, that this interrupt can be gen-

erated, whenever the XRT7250 Framer IC

declares or clears the LOS defect. Hence, the

user can determine the current state of the LOS

defect by reading the state of Bit 4 (RxLOS)

within the Rx E3 Configuration and Status Regis-

ter - 2, as illustrated below.

If the LOS state is TRUE

1. It should transmit a FERF (Far-End-Receive Fail-

ure) indicator to the Remote Terminal Equipment.

Please see Section 4.2.4.2.1.3 on how to config-

ure the XRT7250 to transmit a FERF indicator to

the Remote Terminal Equipment.

If the LOS state is FALSE

1. It should cease transmitting the FERF indication

to the Remote Terminal Equipment. Please see

Section 4.2.4.2.1.3 on how to control the state of

the “A” bit, which is transmitted on each outbound

E3 frame.

5.3.6.2.2

The Change in Receive OOF Condi-

tion Interrupt

If the Change in Receive OOF Condition Interrupt is

enabled, then the XRT7250 Framer IC will generate

an interrupt in response to either of the following con-

ditions.

1. When the XRT7250 Framer IC declares an OOF

(Out of Frame) Condition, and

2. When the XRT7250 Framer IC clears the OOF

condition.

Conditions causing the XRT7250 Framer IC to de-

clare an OOF Condition.

• If the Receive E3 Framer block (within the XRT7250

Framer IC) detects Framing bit errors, within four

consecutive incoming E3 frames.

Conditions causing the XRT7250 Framer IC to

clear the OOF Condition.

• If the Receive E3 Framer block (within the XRT7250

Framer IC) transitions from the FAS Pattern Verifi-

cation state to the In-Frame state (see Figure 115).

• If the Receive E3 Framer block transitions from the

OOF Condition state to the In-Frame state (see Fig-

ure 115).

Enabling and Disabling the Change in Receive

OOF Condition Interrupt

The user can enable or disable the Change in Re-

ceive OOF Condition Interrupt, by writing the appro-

priate value into Bit 3 (OOF Interrupt Enable), within

RXE3 INTERRUPT STATUS REGISTER - 1 (ADDRESS = 0X14)

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

Not Used

COFA

Interrupt Status

OOF

Interrupt Status

LOF

Interrupt Status

LOS

Interrupt Status

AIS

Interrupt Status

RUR

00010

RXE3 CONFIGURATION & STATUS REGISTER - 2 (ADDRESS = 0X11)

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

RxLOF

Algo

RxLOF

RxOOF

RxLOS

RxAIS

Not Used

RxFERF

R/W

RORO

RORORORO

1100

111

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