COM20020 Datasheet, PDF (3/72 Pages) SMSC Corporation – COM20020 3.3V ULANC Universal Local Area Network Controller with 2K x 8 On-Board RAM

TABLE OF CONTENTS
FEATURES.............................................................................................................................................. 1
GENERAL DESCRIPTION ...................................................................................................................... 1
GENERAL DESCRIPTION ...................................................................................................................... 2
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 .............................................................................................................. 23
MICROSEQUENCER........................................................................................................................ 23
INTERNAL REGISTERS ................................................................................................................... 26
INTERNAL RAM................................................................................................................................ 39
COMMAND CHAINING ..................................................................................................................... 44
INITIALIZATION SEQUENCE ........................................................................................................... 46
IMPROVED DIAGNOSTICS.............................................................................................................. 47
OPERATIONAL DESCRIPTION............................................................................................................ 49
MAXIMUM GUARANTEED RATINGS* ............................................................................................. 49
DC ELECTRICAL CHARACTERISTICS ........................................................................................... 49
TIMING DIAGRAMS .............................................................................................................................. 52
APPENDIX A ......................................................................................................................................... 67
APPENDIX B ......................................................................................................................................... 71
SOFTWARE IDENTIFICATION OF THE COM20020 REV B, REV C AND REV D .............................. 71
COM20020 REVISIONS ........................................................................................................................ 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.
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