Embedded System

What is an embedded system?

An embedded system is a special-purpose computer system designed to perform one or a few dedicated functions, often with real-time computing constraints. It is usually embedded as part of a complete device including hardware and mechanical parts. In contrast, a general-purpose computer, such as a personal computer, can do many different tasks depending on programming. Embedded systems control many of the common devices in use today.

Since the embedded system is dedicated to specific tasks, design engineers can optimize it, reducing the size and cost of the product, or increasing the reliability and performance. Some embedded systems are mass-produced, benefiting from economies of scale.

Physically, embedded systems range from portable devices such as digital watches and MP4 players, to large stationary installations like traffic lights, factory controllers, or the systems controlling nuclear power plants. Complexity varies from low, with a single microcontroller chip, to very high with multiple units, peripherals and networks mounted inside a large chassis or enclosure.

In general, "embedded system" is not an exactly defined term, as many systems have some element of programmability. For example, Handheld computers share some elements with embedded systems — such as the operating systems and microprocessors which power them — but are not truly embedded systems, because they allow different applications to be loaded and peripherals to be connected.

Characteristics of Embedded Systems

The key characteristic of an embedded system is that it is supposed to handle a few simple tasks, although the steps involved in handling or accomplishing that task may be as complex as any computer program. A videogame controller, for example, may be said to have simple tasks - load the game and allow the player to control it through commands entered through the handset. In truth, however, a game controller (especially the newer games built for the X-box or PS3) goes through a series of steps and actions that require as much processing power as a standalone computer. Among the characteristics of modern embedded systems are:
User Interfaces

Originally, an embedded system had no user interface - information and programs were already incorporated into the system (e.g., the guidance system for an Intercontinental Ballistic Missile or ICBM) and there was no need for human interaction or intervention except to install the device and test it.

Many modern embedded systems however, have full-scale user interfaces although these are only inputs for data but are not supposed to provide additional functionality for the system, e.g. QWERTY keyboards for PDAs used to enter names, addresses, phone numbers and notes and even full sized documents. The moment PDAs achieve full desktop computer functionalities, however, they may no longer be considered embedded systems.

Simple Systems which Stem from Limited Functionality

Originally, this referred to basic systems such as switches, small character- or digit-only displays and LEDs intended to show the 'health' of the embedded system, but this has also achieved some level of complexity. A cash register or an ATM with touch screen technology is considered an embedded system since it has limited uses, even if the user interface (the touch screen) is a complex system.

CPU Platforms with Microprocessors or Microcontrollers

Again, limited functionality is the key in defining these as embedded systems. In a sense, the BIOS chip is considered an embedded system since it has limited functions, and works automatically (when the computer is booted up). Peripherals like the USB can also be considered as embedded systems.