Microcontrollers target time-critical automotive applications

-- EDN, 11/23/2000

A pair of automotive microcontrollers from NEC Electronics shows how far cars have come from just a few years ago. The 32-bit devices include both a hardware-based CAN (car-area-network) bridge and time-triggered functions for real-time-critical operations. The time trigger means that the controller lets input signals have dedicated time slots, rather than be subject to the vagaries of standard arbitration for external-event service requests. In addition, this feature ensures that regular keep-alive messages flow between the microcontroller and other auto subsystems, and the processor can quickly flag any time-out conditions. For managing the CAN interfaces, hardware within the microcontrollers reduces the CPU load; this hardware includes a programmable state machine, a buffer area that stores commands before the state machine executes them, and other data buffers.

NEC based both microcontrollers, Atomic and CarGate, on the company's V850E RISC architecture, and they operate at 20 and 24 MHz, respectively. The Atomic device includes three full-CAN interfaces, 256 kbytes of ROM, an LCD controller, a 12-channel A/D converter, and a variety of 16- and 32-bit timers. The CarGate device has half the on-chip ROM but has five CAN interfaces and a four-channel A/D converter. Flash-memory versions of these microcontrollers are available. The Atomic microcontroller costs less than $8 (10,000), and the CarGate costs less than $5.

NEC Electronics Inc, www.necel.com.

at www.rscahners.ims.ca/ednmag/.

-by Bill Schweber