COM20020D datasheet(3/72 Pages) SMSC

3 / 72 page

TABLE OF CONTENTS

FEATURES ....................................................................................................................................... 1

GENERAL DESCRIPTION ................................................................................................................ 1

PIN CONFIGURATION ...................................................................................................................... 4

DESCRIPTION OF PIN FUNCTIONS ................................................................................................. 5

PROTOCOL DESCRIPTION.............................................................................................................. 8

NETWORK PROTOCOL ............................................................................................................... 8

DATA RATES ............................................................................................................................... 8

NETWORK RECONFIGURATION ................................................................................................. 9

BROADCAST MESSAGES.......................................................................................................... 10

EXTENDED TIMEOUT FUNCTION ............................................................................................. 10

LINE PROTOCOL ....................................................................................................................... 10

SYSTEM DESCRIPTION ................................................................................................................. 13

MICROCONTROLLER INTERFACE ............................................................................................ 13

TRANSMISSION MEDIA INTERFACE ......................................................................................... 17

FUNCTIONAL DESCRIPTION ......................................................................................................... 22

MICROSEQUENCER .................................................................................................................. 22

INTERNAL REGISTERS ............................................................................................................. 25

INTERNAL RAM ......................................................................................................................... 38

COMMAND CHAINING ............................................................................................................... 43

INITIALIZATION SEQUENCE...................................................................................................... 45

IMPROVED DIAGNOSTICS ........................................................................................................ 46

OPERATIONAL DESCRIPTION ...................................................................................................... 49

MAXIMUM GUARANTEED RATINGS* ........................................................................................ 49

DC ELECTRICAL CHARACTERISTICS....................................................................................... 49

TIMING DIAGRAMS ........................................................................................................................ 52

APPENDIX A................................................................................................................................... 67

APPENDIX B: EXAMPLE OF INTERFACE CIRCUIT DIAGRAM TO ISA BUS ................................ 71

APPENDIX C................................................................................................................................... 72

SOFTWARE IDENTIFICATION OF THE COM20020 REV B, REV C AND REV D ............................ 72

For more details on the ARCNET protocol engine and traditional dipulse signaling schemes,

please refer to the ARCNET Local Area Network Standard, available from Standard Microsystems

Corporation or the ARCNET Designer's Handbook, available from Datapoint Corporation.

For more detailed information on cabling options including RS485, transformer-coupled RS-485

and Fiber Optic interfaces, please refer to the following technical note which is available from

Standard Microsystems Corporation: Technical Note 7-5 - Cabling Guidelines for the COM20020

ULANC.

COM20020D Scheda tecnica(PDF) 3 Page - SMSC Corporation