COM20020I_0609 Datasheet, PDF (5/69 Pages) SMSC Corporation – 5Mbps ARCNET (ANSI 878.1) Controller with 2K x 8 On-Chip RAM

5Mbps ARCNET (ANSI 878.1) Controller with 2K x 8 On-Chip RAM
Chapter 1 General Description
SMSC's COM20020I 3V is a member of the family of Embedded ARCNET Controllers from Standard Microsystems
Corporation. The device is a general purpose 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 COM20020I
3V make it the only true network controller optimized 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 5 Mbps when using the
COM20020I 3V.
A token-passing protocol provides predictable response times because each network event occurs within a
predetermined 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 5
Mbps maximum data rate, and the internal diagnostics make the COM20020I 3V the highest performance embedded
communications device available. With only one COM20020I 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 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 COM20020I 3V ULANC.
SMSC COM20020I 3.3V Rev.E
Page 5
DATASHEET
Revision 09-11-06