DP83255AVF datasheet(4/96 Pages) NSC

4 / 96 page

20 Architecture Description

21 OVERVIEW

The PLAYER device is comprised of four blocks Receiver

Transmitter Configuration Switch and Control Bus Interface

as shown in

Figure 2-1

Receiver

During normal operation the Receiver Block accepts serial

data as inputs at the rate of 125 Mbps from the Clock Re-

covery Device (DP83231) During the Internal Loopback

mode of operation the Receiver Block accepts data from

the Transmitter Block as inputs

The Receiver Block performs the following operations

Converts the incoming data stream from NRZI to NRZ if

necessary

Decodes the data from 5B to 4B coding

Converts the serial bit stream into 10-bit bytes

Compensates for the differences between the upstream

and local clocks

Decodes Line States

Detects link errors

Finally the Receiver Block presents data symbol pairs

(bytes) to the Configuration Switch Block

Configuration Switch

An FDDI station may be in one of three configurations Iso-

late Wrap or Thru The Configuration Switch supports these

configurations by switching the transmitted and received

data paths between the PLAYER and BMAC devices

The configuration switching is performed internally there-

fore no external logic is required for this function

Transmitter

The Transmiter Block accepts 10-bit bytes from the Config-

uration Switch

The Transmitter Block performs the following operations

Encodes the data from 4B to 5B coding

Filters out code violations from the data stream

Generates Idle Master Halt Quiet or other user defined

symbol pairs upon request

Converts the data stream from NRZ to NRZI format

ready for transmission if necessary

Provides smoothing function when necessary

During normal operation the Transmitter Block presents se-

rial data to the fiber optic transmitter While in the External

Loopback mode the Transmitter Block presents serial data

to the Clock Recovery Device

Control Bus Interface

The Control Bus Interface allows a user to

Program the Configuration Switch

Enabledisable functions within the Transmitter and Re-

ceiver Blocks (ie NRZNRZI Encoder Smoother PHY

Request Data Parity Line State Generation Symbol Pair

Injection NRZNRZI Decoder Cascade Mode etc)

The Control Bus Interface also performs the following func-

tions

Monitors Line States received

Monitors link errors detected by the Receiver Block

Monitors other error conditions

22 INTERFACES

The PLAYER device connects to external components via 5

functional interfaces Serial Interface PHY Port Interface

Control Bus Interface Clock Interface and the Miscellane-

ous Interface

Serial Interface

The Serial Interface connects the PLAYER device to a fiber

optic transmitter (FOTX) and the Clock Recovery Device

(DP83231)

TLF10386 – 2

FIGURE 2-1 PLAYER Device Block Diagram

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