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SMSC Corporation |
COM20051+
www.DataSheet4U.com
Integrated Microcontroller and Network
Interface with Watchdog Timer and A/D
Converter Interface
FEATURES
• Low Cost
• Microcontroller Based on Popular 8051
• 5 Mbps to 156 Kbps Network Data Rate
Architecture
• Network Interface Supports RS-485,
• Intel 8051 Code Compatible
Twisted Pair, Coaxial, and Fiber Optic
• 68 Pin PLCC
Interfaces
• Network Supports up to 255 Nodes
• Receive All Mode Allows Any Packet to Be
• Powerful Network Diagnostics
Received
• Maximum 512 Byte Packets
• On-Board Programmable Watchdog Timer
• Duplicate Node ID Detection
• Analog Data Acquisition Port
• Self-Configuring Network Protocol
• Retains all 8051 Peripherals Including
- Interfaces to Any A/D Converter up to
16 Bits Wide
Serial I/O and Two Timers
- Sampling Rates from 1 s to 100ms
• Utilizes ARCNET® Token Bus Network
Engine
Possible
- Decouples 80C32 from Repetitive
• Requires No Special Emulators
Sampling Tasks
GENERAL DESCRIPTION
The COM20051+ is a low-cost, highly-integrated
microcontroller incorporating a high-
performance network controller based on the
ARCNET Token Bus Standard (ANSI 878.1).
The COM20051+ is based around the popular
Intel 8051 architecture. The device is
implemented using a microcontroller core
similar to the Intel 80C32 ROMless version of
the 8051 architecture. The COM20051+ is ideal
for distributed control networking applications
such as those found in industrial/machine
controls, building/factory automation, consumer
products, instrumentation, and automobiles.
The COM20051+ contains many features that
are beneficial for embedded control
applications. The microcontroller is a fully-
functional 16MHz 80C32 that is comparable to
the Intel 80C32. In contrast to other embedded
controller/networking solutions, the COM20051+
adds a fully-featured, robust, powerful, and
simple network interface, watchdog timer, and
data acquisition port, while retaining all of the
basic 8051 peripherals, such as the serial port
and counter/timers.
TABLE OF CONTENTS
FEATURES .......................................................................................................................................1
GENERAL DESCRIPTION.................................................................................................................1
PIN CONFIGURATION......................................................................................................................3
OVERVIEW.......................................................................................................................................4
DESCRIPTION OF PIN FUNCTIONS ................................................................................................5
BASIC ARCHITECTURE ...................................................................................................................8
PROTOCOL DESCRIPTION............................................................................................................14
NETWORK PROTOCOL............................................................................................................14
DATA RATES ............................................................................................................................14
NETWORK RECONFIGURATION .............................................................................................14
BROADCAST MESSAGES ........................................................................................................16
EXTENDED TIMEOUT FUNCTION............................................................................................16
LINE PROTOCOL......................................................................................................................17
SYSTEM DESCRIPTION ..................................................................................................................20
MICROCONTROLLER INTERFACE ..........................................................................................20
TRANSMISSION MEDIA INTERFACE .......................................................................................20
ARCNET CORE FUNCTIONAL DESCRIPTION ................................................................................28
MICROSEQUENCER.................................................................................................................28
INTERNAL REGISTERS............................................................................................................28
INTERNAL RAM ........................................................................................................................40
COMMAND CHAINING..............................................................................................................44
RESET DETAILS .......................................................................................................................47
INITIALIZATION SEQUENCE ....................................................................................................47
IMPROVED DIAGNOSTICS.......................................................................................................48
COM20051+ APPLICATIONS INFORMATION..................................................................................60
USING ARCNET DIAGNOSTICS TO OPTIMIZE YOUR SYSTEM.....................................................78
CABLING THE COM20051+ .............................................................................................................82
USING THE COM20051+'S EMULATION MODE ..............................................................................83
OPERATIONAL DESCRIPTION........................................................................................................84
MAXIMUM GUARANTEED RATINGS ........................................................................................84
DC ELECTRICAL CHARACTERISTICS .....................................................................................84
TIMING DIAGRAMS ..................................................................................................................86
80 Arkay Drive
Hauppauge, NY 11788
(516) 435-6000
FAX (516) 273-3123
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