Microcontrollers: principles and real-time aspects

Microcontrollers are, and will continue to be, widely used for regulation and process control applications. They are true microcomputers integrated on a silicon chip, featuring a CPU, memory or an interface to external memory, input/output ports, a serial line interface (RS-232) and a time and event management unit. The microcontroller's I/O signals can be easily interfaced to optical couplers for interfacing industrial sensors and actuators.

Virtually all microprocessor manufacturers (Motorola, Intel, Hitachi, Texas Instrument, Toshiba, ST Microelectronics-ex SGS-Thomson, etc.) offer one or more ranges of microcontrollers. 4-bit microcontrollers are mainly used for simple tasks. Such microcontrollers are used, for example, in consumer household appliances such as stoves, washing machines and vacuum cleaners. 8-bit microcontrollers are capable of meeting more demanding requirements, and are used to control IT devices such as joysticks, graphics tablets and modems. They are also used for programming small robots and for data acquisition (A/D converters, etc.). 16/32-bit microcontrollers are used for machine or process control, when real-time constraints are severe or when control algorithms require high computing power. Microcontroller variants with direct memory access channels offering high throughput between memory and I/O are used in multimedia applications and for laser printer control.