XRT7250 datasheet(241/463 Pages) EXAR

241 / 463 page

XRT7250

DS3/E3 FRAMER IC

áç

REV. 1.1.1

222

Setting this bit-field to “1” enables the Receive Sec-

tion (at the Block Level) for interrupt generation. Con-

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

ceive Section for interrupt generation.

4.3.6.2

Enabling/Disabling and Servicing

Receive Section Interrupts

As mentioned earlier, the Receive Section of the

XRT7250 Framer IC contains numerous interrupts.

The Enabling/Disabling and Servicing of each of

these interrupts is described below.

4.3.6.2.1

The Change of State on Receive LOS

Interrupt

If the Change of State on Receive LOS (Loss of Sig-

nal) Interrupt is enabled, then the XRT7250 Framer

IC will generate an interrupt in response to either of

the following conditions.

1. When the XRT7250 Framer IC declares an LOS

(Loss of Signal) condition, and

2. When the XRT7250 Framer IC clears the LOS

(Loss of Signal) condition.

Conditions causing the XRT7250 Framer IC to de-

clare an LOS condition

• If the XRT7300 LIU IC declares an LOS condition,

and drives the RLOS input pin (of the XRT7250

Framer IC) "High".

• If the XRT7250 Framer IC detects a 180 consecu-

tive “0’s”, via the RxPOS and RxNEG input pins.

Conditions causing the XRT7250 Framer IC to

clear the LOS condition.

• When the XRT7300 LIU IC ceases declaring an

LOS condition and drives the RLOS input pin (of

the XRT7250 Framer IC) "Low".

• When the XRT7250 Framer IC detects at least 60

marks (via the RxPOS and RxNEG input pins) out

of 180 bit-periods.

Enabling and Disabling the Change of State on

Receive LOS Interrupt:

The user can enable or disable the Change of State

on Receive LOS Interrupt, by writing the appropriate

value into Bit 6 (LOS 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 LOS 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 this pin "Low".

BLOCK INTERRUPT ENABLE REGISTER (ADDRESS = 0X04)

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

RxDS3/E3

Interrupt

Enable

Not Used

TxDS3/E3

Interrupt

Enable

One Second

Interrupt

Enable

R/W

RORO

R/W

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

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