SMSC COM20020 用户手册
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TABLE OF CONTENTS
FEATURES ........................................................................................................................................1
GENERAL DESCRIPTION .................................................................................................................1
PIN CONFIGURATION.......................................................................................................................3
DESCRIPTION OF PIN FUNCTIONS .................................................................................................4
PROTOCOL DESCRIPTION ..............................................................................................................8
NETWORK PROTOCOL ....................................................................................................................8
DATA RATES .....................................................................................................................................8
NETWORK RECONFIGURATION ......................................................................................................8
BROADCAST MESSAGES .................................................................................................................9
EXTENDED TIMEOUT FUNCTION.....................................................................................................9
LINE PROTOCOL ............................................................................................................................10
DATA RATES .....................................................................................................................................8
NETWORK RECONFIGURATION ......................................................................................................8
BROADCAST MESSAGES .................................................................................................................9
EXTENDED TIMEOUT FUNCTION.....................................................................................................9
LINE PROTOCOL ............................................................................................................................10
SYSTEM DESCRIPTION..................................................................................................................12
MICROCONTROLLER INTERFACE .................................................................................................12
TRANSMISSION MEDIA INTERFACE ..............................................................................................15
TRANSMISSION MEDIA INTERFACE ..............................................................................................15
FUNCTIONAL DESCRIPTION..........................................................................................................19
MICROSEQUENCER .......................................................................................................................19
INTERNAL REGISTERS...................................................................................................................22
INTERNAL RAM ...............................................................................................................................32
COMMAND CHAINING.....................................................................................................................37
INITIALIZATION SEQUENCE ...........................................................................................................40
IMPROVED DIAGNOSTICS .............................................................................................................40
INTERNAL REGISTERS...................................................................................................................22
INTERNAL RAM ...............................................................................................................................32
COMMAND CHAINING.....................................................................................................................37
INITIALIZATION SEQUENCE ...........................................................................................................40
IMPROVED DIAGNOSTICS .............................................................................................................40
OPERATIONAL DESCRIPTION .......................................................................................................43
MAXIMUM GUARANTEED RATINGS*..............................................................................................43
DC ELECTRICAL CHARACTERISTICS ............................................................................................43
DC ELECTRICAL CHARACTERISTICS ............................................................................................43
TIMING DIAGRAMS ........................................................................................................................46
COM20020 ERRATA SHEET ...........................................................................................................59
For more details on the ARCNET protocol engine and traditional dipulse signalling 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.
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.
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.