What is a microcontroller?  (Page 3/5)

A self contained electronic control system, generally with limited user input/output. A traffic light control system is a good example of an embedded system. The system is self-contained and controls the flow of vehicles at an intersection. Users (pedestrians, bicyclists and car drivers) interact with the system in a limited manner. There may be sensors that detect the presence of vehicles and buttons for pedestrians to push when they want to cross the intersection. The traffic lights output the "state" of the system and inform the users of the actions they must take. The best desinged embedded systems are those that are unobtrusive to the user. That is, they require little user interaction and, for the most part, are "invisible."