SMSC COM20020 manual Features, General Description

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COM20020

COM20020 ULANC

Universal Local Area Network Controller

with 2K x 8 On-Board RAM

FEATURES

∙24-Pin Embedded Network Controller/ Transceiver/RAM

∙Ideal for Industrial/Factory Automation and Automotive Applications

∙Deterministic, 2.5 Mbps, Token Passing ARCNET Protocol

∙Minimal Microcontroller and Media Interface Logic Required

∙Flexible Microcontroller Interface for Use with 80XX, 68XX, etc.

∙Automatically Detects Type of Microcontroller Interface:

-Non-Multiplexed or Multiplexed Bus

-Separate nRD & nWR Lines or DIR & nDS Lines

∙Full 2Kx8 On-Chip RAM

∙Command Chaining for Top Performance

∙Reduced Reconfiguration Times

∙Sequential Access to Internal RAM

∙Software Programmable Node ID

∙Duplicate Node ID Detection

∙Powerful Diagnostics

∙Receive All Mode

∙Data Rates from 2.5 Mbps to 156.25 Kbps

∙24-Pin DIP or 28-Pin PLCC Package

∙Flexible Media Interface:

-Traditional Hybrid Interface for Long Distances

-RS485 Differential Driver Interface for Low Cost, Low Power, High Reliability

-Backplane Mode for Direct Connection to Media in Short Distance Applications

∙Eight, 256-Byte Pages Allow 4 Pages TX and RX Plus Scratch-Pad Memory

∙No Wait-State Arbitration

∙Programmable TXEN Polarity

∙Next ID Readable

∙Internal Clock Prescaler for Slower Network Speed without Slowing Arbitration

∙Operating Temperature Range of -40oC to +85oC, or 0oC to +70oC

∙Self-Reconfiguration Protocol

∙Supports up to 255 Nodes

∙Supports Various Network Topologies (Star, Tree, Bus...)

∙CMOS, Single +5V Supply

GENERAL DESCRIPTION

SMSC's COM20020 is a member of the family of Industrial Network Controllers from Standard Microsystems Corporation. The device is a special purpose communications controller for networking microcontrollers and intelligent peripherals in industrial, automotive, and

embedded control environments using an ARCNET® protocol engine. The small 24-pin package, flexible microcontroller and media interfaces, eight-page message support, and extended temperature range of the COM20020

make it the only true network

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Contents General Description FeaturesTable of Contents PIN Configuration A1,A2/ALE Description of PIN FunctionsTransmission Media Interface DIP PIN Plcc PIN Name Symbol DescriptionMiscellaneous Instead, it must be connected to XTAL1 with COM20020 Operation Protocol Description Network ReconfigurationNetwork Protocol Data RatesBroadcast Messages Extended Timeout FunctionResponse Time Idle Time Reconfiguration TimeLine Protocol Invitations To TransmitAcknowledgements Data PacketsNegative Acknowledgements System Description MULTIPLEXED, 8051-LIKE BUS Interface with RS-485 Interface Figure C Traditional Hybrid Interface Backplane ConfigurationCOM20020 Network Using RS-485 Differential Transceivers Programmable Txen Polarity Differential Driver ConfigurationInternal Block Diagram Attenuation Functional DescriptionNominal Cable Type Impedance AT 5MHZRead Register Summary Write Interrupt Mask Register IMR Internal RegistersData Register Tentative ID RegisterCommand Register Diagnostic Status RegisterNext ID Register Status RegisterConfiguration Register Setup Register BIT BIT Name Symbol Description Dupid BIT BIT Name Symbol DescriptionData Command Description Address Pointer Low Register Address Pointer High RegisterReset Configuration RegisterCKP3 CKP2 CKP1 Sequential Access Operation Access Speed Sequential Access MemoryInternal RAM Software InterfaceTransmit Sequence Selecting RAM Page SizeRAM Buffer Packet Configuration Page Receive Sequence Transmit Command Chaining Command ChainingReceive Command Chaining Internal Reset Logic Reset DetailsInitialization Sequence Improved DiagnosticsAbnormal Results Normal ResultsOscillator DC Electrical Characteristics Maximum Guaranteed RatingsParameter Symbol MIN TYP MAX Unit Comment Operational DescriptionXTAL1, XTAL2 Input Capacitance Multiplexed BUS, 68XX-LIKE Control Signals Read Cycle Timing DiagramsMultiplexed BUS, 80XX-LIKE Control Signals Read Cycle Multiplexed BUS, 68XX-LIKE Control Signals Write Cycle Multiplexed BUS, 80XX-LIKE Control Signals Write Cycle NON-MULTIPLEXED BUS, 80XX-LIKE Control Signals Read Cycle NON-MULTIPLEXED BUS, 68XX-LIKE Control Signals Read Cycle NON-MULTIPLEXED BUS, 80XX-LIKE Control Signals Write Cycle NON-MULTIPLEXED BUS, 68XX-LIKE Control Signals Write Cycle These signals are to and from the hybrid Normal Mode Transmit or Receive TimingNTXEN NPULSE1 TTL Input Timing on XTAL1 PIN 28-PIN Plcc Package Dimensions 24-PIN DIP Package Dimensions SECTION/FIGURE/ENTRY Correction Revised DateStandard Microsystems Corp
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