XRT7250 datasheet(245/463 Pages) EXAR

245 / 463 page

XRT7250

DS3/E3 FRAMER IC

áç

REV. 1.1.1

226

If the AIS Condition is TRUE

1. The Local Terminal Equipment should transmit a

FERF (Far-End Receive Failure) to the Remote

Terminal Equipment. The XRT7250 Framer IC

automatically supports this action via the FERF-

upon-AIS feature.

2. It should transmit the appropriate FEAC Message

(per Bellcore GR-499-CORE), to the Remote Ter-

minal, indicating that a Service Affecting condi-

tion has been detected in the Local Terminal

Equipment.

If the AIS Condition is FALSE

1. The Local Terminal Equipment should cease

transmitting a FERF (Far-End Receive Failure)

indicator to the Remote Terminal Equipment.

The XRT7250 Framer IC automatically supports

this action via the FERF-upon-AIS feature.

2. It should transmit the appropriate FEAC Message

(per Bellcore GR-499-CORE) to the Remote Ter-

minal, indicates that the Service Affecting condi-

tion no longer exists.

4.3.6.2.4

The Change of State of Receive Idle

Interrupt

If the Change of State on Receive Idle Interrupt is en-

abled, then the XRT7250 Framer IC will generate an

interrupt in response to either of the following condi-

tions.

1. When the XRT7250 Framer IC detects an Idle

pattern, in the incoming DS3 data stream, and

2. When the XRT7250 Framer IC no longer detects

the Idle pattern in the incoming DS3 data stream.

Conditions causing the XRT7250 Framer IC to de-

clare an Idle condition

• If the Receive DS3 Framer block (within the

XRT7250 Framer IC) detects at least 63 DS3

frames, which contains the Idle pattern.

Conditions causing the XRT7250 Framer IC to

clear the Idle condition.

• Whenever, the Receive DS3 Framer block detects

63 DS3 frames, which do not contain the Idle pat-

tern.

Enabling and Disabling the Change of State on

Receive Idle Interrupt:

The user can enable or disable the Change of State

on Receive Idle Interrupt, by writing the appropriate

value into Bit 4 (Idle Interrupt Enable) within the

RxDS3 Interrupt Enable Register, as illustrated below.

Setting this bit-field to “1” enables this interrupt. Con-

versely, setting this bit-field to “0” disables this inter-

rupt.

Servicing the Change of State on Receive Idle In-

terrupt

Whenever the XRT7250 Framer IC detects this inter-

rupt, it will do all of the following.

• It will assert the Interrupt Request Output pin (INT)

by driving it "Low".

• It will set Bit 4 (Idle Interrupt Status), within the Rx

DS3 Interrupt Status Register to “1”, as indicated

below.

RXDS3 CONFIGURATION & STATUS REGISTER (ADDRESS = 0X10)

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

RxAIS

RxLOS

RxIdle

RxOOF

Reserved

Framing On

Parity

FSync

Algo

MSync

Algo

RUR

000

RXDS3 INTERRUPT ENABLE REGISTER (ADDRESS = 0X12)

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

CP Bit Error

Interrupt

Enable

LOS

Interrupt

Enable

AIS

Interrupt

Enable

Idle Interrupt

Enable

FERF

Interrupt

Enable

AIC

Interrupt

Enable

OOF

Interrupt

Enable

P-Bit Error

Interrupt

Enable

R/W

000

XRT7250 Datasheet(PDF) 245 Page - Exar Corporation

XRT7250 Datasheet(HTML) 245 Page - Exar Corporation

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