DP83261AVF datasheet(73/132 Pages) NSC

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70 Signal Descriptions (Continued)

721 PHY Interface Codes

The DP83251155 PLAYER device converts the Standard 4B5B FDDI symbol code to the internal code used at the PHY

Interface The PH

DATAIndication table shows how the Ring Engine interprets the codes generated by the PLAYER device

and the PH

DATA Request table shows the codes generated by the Ring Engine

The internal code is actually an 8B9B code with parity where one bit is used to determine whether the symbol pair contains two

data symbols or at least one control symbol

DATAIndication

The Ring Engine interprets the byte stream the PLAYER device as defined in Table 7-1

TABLE 7-1 Internal PHY Indicate Coding

Value

PIP

PIC

PID(7 – 4)

PID(3 – 0)

Type

0000

Data Symbol Pair

0000

0001

Data Symbol Pair

254

1111

1110

Data Symbol Pair

255

1111

Data Symbol Pair

1101

xxxx

Start Delimiter

x011

x1xx

Invalid

x011

xx1x

Invalid

10xx

xxxx

Idle Symbols

0000

10xx

DataIdle Symbol

0110

Frame Status

0110

0111

Frame Status

0110

0101

Frame Status

0111

Frame Status

0111

0110

Frame Status

0111

0101

Frame Status

0111

xxxx

Frame Status

0101

xxxx

Ending Delimiter

0101

0110

Ending Delimiter

0101

0111

Ending Delimiter

0101

Ending Delimiter

0000

0101

Mixed Symbol Pair

Parity Error

Code Violation

Otherwise

Else

Code Violation

where

PIP

PHY Indicate Parity bit ODD parity

PIC

PHY Indicate Control bit

0eldata byte

1elcontrolmixed byte

PID(7 – 0) PHY Indicate Data(7 – 0)

represents ODD Parity (EP is Bad Parity)

x –

represents a don’t care and is not decoded

representsa1or0but not both

The PLAYER device aligns the received JK to a byte boundary Thus no provision is made in the internal code or by the Ring

Engine for off boundary JKs

The Idle and PH

Invalid encodings overlap Idle symbols received while the PLAYER device is in Active Line State (ALS) or Idle

Line State (ILS) are not considered PH

INVALID Idle symbols received while the PLAYER device is in states other than ALS or

ILS are treated as PH

Invalid

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