Cost Competitive ARCNET (ANSI 878.1) Controller with
2K x 8 On-Chip RAM
Highlights
• Data Rates up to 312.5 Kbps
• Programmable Reconfiguration Times
• 28-Pin PLCC and 48-Pin TQFP RoHS Compliant
packages
• Ideal for Industrial/Factory/Building Automation
and Transportation Applications
• Deterministic, (ANSI 878.1), Token Passing ARC-
NET Protocol
• Minimal Microcontroller and Media Interface Logic
Required
• Flexible Interface For Use With All Microcontrol-
lers or Microprocessors
• Automatically Detects Type of Microcontroller
Interface
• 2Kx8 On-Chip Dual Port RAM
• Command Chaining for Packet Queuing
• Sequential Access to Internal RAM
• Software Programmable Node ID
• Eight, 256 Byte Pages Allow Four Pages TX and
RX Plus Scratch-Pad Memory
• Next ID Readable
• Internal Clock Scaler for Adjusting Network Speed
• Operating Temperature Range of -40
o
C to +85
o
C
• 3.3V power supply with 5V tolerant I/O
• Self-Reconfiguration Protocol
• Supports up to 255 Nodes
• Supports Various Network Topologies (Star, Tree,
Bus...)
• CMOS, Single +3.3V Supply
• Duplicate Node ID Detection
• Powerful Diagnostics
• Receive All Packets Mode
• Flexible Media Interface:
- RS485 Differential Driver Interface For Cost
Competitive, Low Power, High Reliability
2001-2018 Microchip Technology Inc.
DS00002694A-page 1
COM20019i 3.3V Rev. C
TO OUR VALUED CUSTOMERS
It is our intention to provide our valued customers with the best documentation possible to ensure successful use of your Microchip
products. To this end, we will continue to improve our publications to better suit your needs. Our publications will be refined and
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The last character of the literature number is the version number, (e.g., DS30000000A is version A of document DS30000000).
Errata
An errata sheet, describing minor operational differences from the data sheet and recommended workarounds, may exist for cur-
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To determine if an errata sheet exists for a particular device, please check with one of the following:
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DS00002694A-page 2
2001-2018 Microchip Technology Inc.
COM20019i 3.3V Rev. C
Table of Contents
1.0 General Description ........................................................................................................................................................................ 4
5.0 System Description ....................................................................................................................................................................... 13
Appendix A: Function of NOSYNC and EF Bits .................................................................................................................................. 57
Appendix B: Example of Interface Circuit Diagram to ISA Bus ........................................................................................................... 59
Appendix C: Software Identification of the COM20019i 3V Rev. B and Rev. C .................................................................................. 60
Appendix D: Data Sheet Revision History .......................................................................................................................................... 61
2001-2018 Microchip Technology Inc.
DS00002694A-page 3
COM20019i 3.3V Rev. C
1.0
GENERAL DESCRIPTION
Microchip's COM20019i 3V is a member of the family of Embedded ARCNET Controllers. The device is a general pur-
pose communications controller for networking microcontrollers and intelligent peripherals in industrial and embedded
control environments using an ARCNET protocol engine. The flexible microcontroller and media interfaces, eight-page
message support, and extended temperature range of the COM20019i 3V make it the only true network controller opti-
mized for use in industrial and embedded applications. Using an ARCNET protocol engine is the ideal solution for
embedded control applications because it provides a deterministic token-passing protocol, a highly reliable and proven
networking scheme, and a data rate of up to 312.5 Kbps when using the COM20019i 3V.
A token-passing protocol provides predictable response times because each network event occurs within a predeter-
mined time interval, based upon the number of nodes on the network. The deterministic nature of ARCNET is essential
in real time applications. The integration of the 2Kx8 RAM buffer on-chip, the Command Chaining feature, the maximum
data rate, and the internal diagnostics make the COM20019i 3V the highest performance embedded communications
device available. With only one COM20019i 3V and one microcontroller, a complete communications node may be
implemented.
For more details on the ARCNET protocol engine and traditional dipulse signaling schemes, please refer to the ARCNET Local
Area Network Standard, available from Microchip 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 Microchip: Technical Note 7-5 - Cabling Guidelines for the
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