DP83255AVF datasheet(92/96 Pages) NSC

92 / 96 page

80 Detailed Descriptions (Continued)

86 NATIONAL BYTE-WIDE CODE FOR PHY-MAC IN-

TERFACE

The PLAYER device outputs the National byte-wide code

from its PHY Port Indicate Output to the MAC device Each

National byte-wide code may contain data or control codes

or the line state information of the connection Table 8-2

lists all the possible outputs

During Active Line State all data and control symbols are

being repeated to the PHY Port Indicate Output with the

exception of data in data-control mixture bytes That data

sybmol is replaced by zero If only one symbol in a byte is a

control symbol the data symbol will be replaced by 0000

and the whole byte will be presented as control code Note

that the Line State Detector recognizes the incoming data

to be in the Active Line State upon reception of the Starting

Delimiter (JK symbol pair)

During Idle Line State any non Idle symbols will be reflected

as the code I’uILS If both symbols received during Idle

Line State are Idle symbols then the Symbol Decoder gen-

erates I’kILS as its output Note that in this case the coded

byte is represented in the form Receive State (b7 – 4)

KnownUnknown Bit (b3) and the Last Known Line State

(b2 – 0) The Receive State is 4 bits long and it represents

either the PHY Invalid (0011) or the Idle Line State (1011)

condition The KnownUnknown Bit shows if the symbols

received match the line state information in the last 3 bits

During any line state other than Idle Line State or Active

Line State the Symbol Decoder generates the code V kLS

if the incoming symbols match the current line state The

symbol decoder generates V’uLS if the incoming symbols

do not match the current line state

DP83255AVF Datasheet(PDF) 92 Page - National Semiconductor (TI)