DP83255AVF datasheet(87/96 Pages) NSC

87 / 96 page

80 Detailed Descriptions

This section describes in detail several functions that had

been discussed previously in Section 30 Functional De-

scriptions

81 FRAMING HOLD RULES

DETECTING JK

The JK symbol pair can be used to detect the beginning of a

frame during Active Line State (ALS) and Idle Line State

(ILS)

While the Line State Detector is in the Idle Line State the

PLAYER device ‘‘reframes’’ upon detecting a JK symbol

pair and enters the Active Line State

During Active Line State acceptance of a JK symbol (re-

framing) is allowed on any on-boundary JK which is detect-

ed at least 15 byte times after the previous JK

During Active Line State once reframed on a JK the subse-

quent off-boundary JK is ignored even if it is detected be-

yond 15 byte times after the previous JK

During Active Line State an Idle or Ending Delimiter (T)

symbol will allow reframing on any subsequent JK if a JK is

detected at least 15 bytes times after the previous JK

DETECTING HALT-HALT

HALT-QUIET

During Idle Line State the detection of a Halt-Halt or Halt-

Quiet symbol pair will still allow the reframing of any subse-

quent on-boundary JK

Once a JK is detected during Active Line State off-bounda-

ry Halt-Halt or Halt-Quiet symbol pairs are ignored until the

Elasticity Buffer (EB) has an opportunity to recenter They

are treated as violations

After recentering on a Halt-Halt or Halt-Quiet symbol pair

all off-boundary Halt-Halt or Halt-Quiet symbol pairs are ig-

nored until the EB has a chance to recenter during a line

state other than Active Line State (which may be as long as

28 byte times)

82 NOISE EVENTS

A Noise Event is defined as follows

A noise event is a noise byte a byte of data which is not in

line with the current line state indicating error or corruption

Noise Event e SD

ECD a

CD PI E(II a JK a AB) a

CD EPI (PB e II) AB

Where

Logical AND

Logical OR

Logical NOT

SD e Signal Detect

CD e Clock Detect

PB e Previous Byte

PLS e Previous Line State

PHY Invalid e HLS

QLS

MLS

NLS a

ULS

PLS e

(ALS a ILS)

ILS e Idle Line State

ALS e Active Line State

ULS e Unknown Line State

HLS e Halt Line State

QLS e Quiet Line State

MLS e Master Line State

NLS e Noise Line State

ULS e Unknown Line State

Idle symbol

First symbol of start delimiter

Second symbol of start delimiter

Reset symbol

Set symbol

End delimiter

n a R a S a T

n a R a S a T a I

Any data symbol

DP83255AVF Datasheet(PDF) 87 Page - National Semiconductor (TI)

DP83255AVF Datasheet(HTML) 87 Page - National Semiconductor (TI)

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