XRT7250 datasheet(457/463 Pages) EXAR

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XRT7250

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DS3/E3 FRAMER IC

REV. 1.1.1

438

• It should read the contents of the PMON Parity

Error Event Count Registers (located at Addresses

0x54 and 0x55) in order to determine the number of

BIP-8 Errors that have been received by the

XRT7250 Framer IC.

6.3.6.2.10 The Detection of Framing Byte Error

Interrupt

If the Detection of Framing Byte Error Interrupt is en-

abled, then the XRT7250 Framer IC will generate an

interrupt, anytime the Receive E3 Framer block has

received an E3 frame with an incorrect Framing Byte

(e.g., FA1 or FA2) value.

Enabling and Disabling the Detection of FEBE

Event Interrupt

The user can enable or disable the Detection of

Framing Byte Error’ interrupt by writing the appropri-

ate value into Bit 1 (Framing Byte Error Interrupt En-

able) within the Rx E3 Interrupt Enable Register - 2,

as indicated below.

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

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

rupt.

Servicing the Detection of Framing Byte Error In-

terrupt

Whenever the XRT7250 Framer IC detects this inter-

rupt, it will do the following.

• It will assert the Interrupt Request output pin (INT),

by driving it “High”.

• It will set the Bit 4 (Framing Byte Error Interrupt Sta-

tus), within the RxE3 Interrupt Status Register - 2

as indicated below.

Whenever the Terminal Equipment encounters the

Detection of Framing Byte Error Interrupt, it should do

the following.

• It should read the contents of the PMON Framing

Bit/Byte Error Count Registers (located at

Addresses 0x52 and 0x53) in order to determine

the number of Framing Byte errors that have been

received by the XRT7250 Framer IC.

6.3.6.2.11 The Detection of Payload Type Mis-

match Interrupt

If the Detection of Payload Type Mismatch Interrupt is

enabled, then the XRT7250 Framer IC will generate

an interrupt, anytime the Receive E3 Framer block re-

ceives a MA byte (within an incoming E3 frame) that

contents a Payload Type value that is different from

the expected Payload Type value.

Conditions causing this interrupt to be generated.

During system configuration, the user is expected to

specify the Payload Type value that is expected of the

Receive E3 Framer to receive (within each E3 frame),

by writing this value into the RxPLDExp[2:0] bit-fields

within the Rx E3 Configuration & Status Register - 1,

as indicated below.

As long as the Receive E3 Framer block receives E3

frames that contains this Payload Type value, no in-

terrupt will be generated. However, the instant that it

receives an E3 frame, that contains a different Pay-

RXE3 INTERRUPT ENABLE REGISTER - 2 (ADDRESS = 0X13)

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

Not Used

TTB

Change

Interrupt

Enable

Not Used

FEBE

Interrupt

Enable

FERF

Interrupt

Enable

BIP-8

Error Interrupt

Enable

Framing

Byte Error

Interrupt

Enable

RxPld

Mis

Interrupt

Enable

R/W

000

RXE3 INTERRUPT STATUS REGISTER - 2 (ADDRESS = 0X15)

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

Not Used

TTB

Change

Interrupt

Status

Not Used

FEBE

Interrupt

Status

FERF

Interrupt

Status

BIP-8

Error Interrupt

Status

Framing

Byte Error

Interrupt

Status

RxPld

Mis

Interrupt

Status

RUR

010

000

XRT7250 Datasheet(PDF) 457 Page - Exar Corporation

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