XRT7250 datasheet(86/463 Pages) EXAR

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DS3/E3 FRAMER IC

XRT7250

REV. 1.1.1

Bit 3 - RxTMark Algorithm

This Read/Write bit-field allows the user to select the

number of consecutive incoming E3 frames, that the

Timing Marker bit-field (within the MA byte-field) must

be of a given logic state, before it is validated by the

Receive E3 Framer. Once the Receive E3 Framer

has validated the state of the Timing Marker bit-field,

then it will write this logic state into Bit 1 (RxTMark)

within the Rx E3 Configuration & Status Register 2

(Address = 0x11)

Writing a "0" into this bit-field causes the Receive E3

Framer to validate the Timing Marker value after re-

ceiving 3 consecutive incoming E3 frames, with the

Timing Marker bit-field of a given value. Writing a "1"

into this bit-field causes the Receive E3 Framer to

validate the Timing Marker value after receiving 5

consecutive incoming E3 frames, with the Timing

Marker bit-field of a given value.

Bits 2 - 0: RxPLDExp[2:0]

This Read/Write bit-field allows the user to specify the

Payload Type that is expected in the MA bytes, of

each incoming E3 frame.

If the Receive E3 Framer detects a Payload Type that

differs from the values within these bit-fields, then the

Framer will generate the Payload Type Mismatch in-

terrupt.

2.3.3.2

Receive E3 Configuration & Status

Bit 7 - RxLOF Algo (Loss of Frame Declaration Al-

gorithm)

This Read/Write bit-field allows the user to select the

LOF (Loss of Frame) Declaration criteria, that will be

used by the Receive E3 Framer. Writing a "0" to this

bit-field configures the Receive E3 Framer to declare

an LOF condition, after it has been in the OOF condi-

tion for 24 frame periods (3 ms). Writing a "1" to this

bit-field configures the Receive E3 Framer to declare

an LOF condition, after it has been in the OOF condi-

tion for 8 frame periods (1 ms).

Bit 6 - RxLOF (Loss of Frame Declaration)

This Read-Only bit-field indicates whether or not the

Receive E3 Framer is currently in the Loss of Frame

(LOF) condition. If this bit-field is set to "1", then the

Receive E3 Framer is currently in the LOF condition.

Conversely, if this bit-field is set to "0", then the Re-

ceive E3 Framer is currently not in the LOF condition.

Bit 5 - RxOOF (Out of Frame Declaration)

This Read-Only bit field indicates whether or not the

Receive E3 Framer is currently experiencing an Out

of Frame (OOF) condition. The Receive E3 Framer

will declare an OOF condition if it has detected errors

in the frame alignment bytes (FA1 and FA2) in four

consecutive frames. If this bit-field is set to "1", then

the Receive E3 Framer has declared, and is continu-

ing to experience an OOF condition. If this bit-field is

set to "0", then the Receive E3 Framer is currently not

experiencing an OOF condition.

Bit 4 - RxLOS (Loss of Signal Declaration)

This Read-Only bit-field indicates whether or not the

Receive E3 Framer is currently experiencing a Loss

of Signal (LOS) condition. The Receive E3 Framer

will declare an LOS condition if it has detected a

string of 32 consecutive "0’s", via the RxPOS and Rx-

NEG input pins. If this bit-field is set to "1", then the

Receive E3 Framer has declared, and is continuing to

experience an LOS condition. If this bit-field is set to

"0", then the Receive E3 Framer is currently not expe-

riencing an LOS condition.

Bit 3 - RxAIS (Alarm Indication Status Declara-

tion)

This Read-Only bit-field indicates whether or not the

Receive E3 Framer is currently experiencing an AIS

condition. The Receive E3 Framer will declare an

AIS condition if it has detected two consecutive E3

frames, that each contain less than seven (7) "0’s" . If

this bit-field is set to "1", then the Receive E3 Framer

has declared, and is continuing to experience an AIS

condition. If this bit-field is set to "0", then the Re-

ceive E3 Framer is currently not experiencing an AIS

condition.

Bit 2 - RxPLDType UnStab

This Read-Only bit-field indicates whether or not the

Receive E3 Framer has been receiving a consistent

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

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

Rx LOF Algo

RxLOF

RxOOF

RxLOS

RxAIS

RxPld Unstab

RxTMark

RxFERF

R/W

RORO

RORORORO

1111

111

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