Handling data rates up to 5 Mbits/s, the COM20020 ARCNET CMOS controller IC runs off 3.3-V supplies at −40°C to 85°C. This general-purpose communications IC for networking microcontrollers and intelligent peripherals can be used in industrial, automotive, and embedded control applications with an ARCNET protocol engine.
The device boasts eight-message support, programmable reconfiguration times, and a self-configuring protocol. The ARCNET protocol provides deterministic token-passing performance according to the ANSI 878.1 specification. Additionally, the IC requires minimal microcontroller and media-interface logic, while its flexible interface targets all microprocessors and microcontrollers.
The COM20020 doesn't blindly interface with controllers. Instead, it automatically identifies their types and responds accordingly. It also features a 2k by 8-bit dual-port RAM, command chaining for packet queuing, sequential access to internal RAM, and a software-programmable node ID. Eight 256-byte pages are on-chip as well. A scratch-pad memory lets users transmit and receive four pages. Network speed is adjustable via an internal clock scaler and multiplier.
This IC supports up to 255 nodes. Various network topologies, such as stars, trees, and buses, are all supported. The chip even sports duplicate-node ID detection, powerful diagnostics, and a flexible media interface. This interface comes with a traditional hybrid interface for distances up to four miles at 2.5 Mbits/s, along with an RS-485 differential interface for low-cost, low-power, and high-reliability interfacing.
The COM20020 is available in a 24-pin DIP or 28-pin PLCC. It costs $11 in 10,000-unit quantities. Delivery is within 12 to 16 weeks.
Standard Microsystems Corp., 80 Arkay Dr., P.O. Box 18047, Hauppauge, NY 11788-8847; (516) 435-6000; www.smsc.com.
