An embedded system is a computer system A computer is a programmable machine that receives input, stores and manipulates data, and provides output in a useful format designed to perform one or a few dedicated functions[1][2] often with real-time computing In computer science, real-time computing , or reactive computing, is the study of hardware and software systems that are subject to a "real-time constraint"—i.e., operational deadlines from event to system response. By contrast, a non-real-time system is one for which there is no deadline, even if fast response or high performance is constraints. It is embedded as part of a complete device often including hardware and mechanical parts. By contrast, a general-purpose computer, such as a personal computer A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end user, with no intervening computer operator. This is in contrast to the batch processing or time-sharing models which allowed large expensive mainframe (PC), is designed to be flexible and to meet a wide range of end-user needs. Embedded systems control many devices in common use today.[3]
Embedded systems are controlled by one or more main processing cores that are typically either microcontrollers A microcontroller is a small computer on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals. Program memory in the form of NOR flash or OTP ROM is also often included on chip, as well as a typically small amount of RAM. Microcontrollers are designed for embedded applications, in contrast to or digital signal processors A digital signal processor is a specialized microprocessor with an optimized architecture for the fast operational needs of digital signal processing (DSP).[4] The key characteristic, however, is being dedicated to handle a particular task, which may require very powerful processors. For example, air traffic control Air traffic control is a service provided by ground-based controllers who direct aircraft on the ground and in the air. The primary purpose of ATC systems worldwide is to separate aircraft to prevent collisions, to organize and expedite the flow of traffic, and to provide information and other support for pilots when able. In some countries, ATC systems may usefully be viewed as embedded, even though they involve mainframe computers Mainframes are powerful computers used mainly by large organizations for critical applications, typically bulk data processing such as census, industry and consumer statistics, enterprise resource planning, and financial transaction processing and dedicated regional and national networks between airports and radar sites. (Each radar probably includes one or more embedded systems of its own.)
Since the embedded system is dedicated to specific tasks, design engineers can optimize it to reduce the size and cost of the product and increase the reliability and performance. Some embedded systems are mass-produced, benefiting from economies of scale Economies of scale, in microeconomics, are the cost advantages that a business obtains due to expansion. They are factors that cause a producer’s average cost per unit to fall as scale is increased. Economies of scale is a long run concept and refers to reductions in unit cost as the size of a facility, or scale, increases. Diseconomies of scale.
Physically, embedded systems range from portable devices such as digital watches A watch is a timepiece that is made to be worn on a person. It is usually a wristwatch, worn on the wrist with a strap or bracelet. In addition to the time, modern watches often display the day, date, month and year, and electronic watches may have many other functions and MP3 players A digital audio player, or DAP, usually referred to as an MP3 player, is a consumer electronic device that has the primary function of storing, organizing and playing audio files. Some DAPs are also referred to as portable media players as they have image-viewing and/or video-playing support, to large stationary installations like traffic lights Traffic lights, which may also be known as stoplights, traffic lamps, traffic signals, stop-and-go lights[citation needed], robots or semaphore, are signaling devices positioned at road intersections, pedestrian crossings and other locations to control competing flows of traffic. Traffic lights have been installed in most cities around the world, factory controllers A programmable logic controller or programmable controller is a digital computer used for automation of electromechanical processes, such as control of machinery on factory assembly lines, amusement rides, or lighting fixtures. PLCs are used in many industries and machines. Unlike general-purpose computers, the PLC is designed for multiple inputs, or the systems controlling nuclear power plants Nuclear power is energy produced from controlled nuclear reactions. Commercial plants currently use nuclear fission reactions to generate electricity. Electric utility reactors heat water to produce steam, which is then used to generate electricity. Complexity varies from low, with a single microcontroller A microcontroller is a small computer on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals. Program memory in the form of NOR flash or OTP ROM is also often included on chip, as well as a typically small amount of RAM. Microcontrollers are designed for embedded applications, in contrast to chip, to very high with multiple units, peripherals and networks mounted inside a large chassis A chassis (pronounced /ˈʃæsi, ˈtʃæsi/) consists of an internal framework that supports a man-made object. It is analogous to an animal's skeleton. An example of a chassis is the under part of a motor vehicle, consisting of the frame (on which the body is mounted) with the wheels and machinery or enclosure.
In general, "embedded system" is not a strictly definable term, as most systems have some element of extensibility or programmability. For example, handheld computers A mobile device is a pocket-sized computing device, typically having a display screen with touch input or a miniature keyboard. In the case of the personal digital assistant (PDA) the input and output are combined into a touch-screen interface. Smartphones and PDAs are popular amongst those who require the assistance and convenience of a share some elements with embedded systems such as the operating systems and microprocessors which power them, but they allow different applications to be loaded and peripherals to be connected. Moreover, even systems which don't expose programmability as a primary feature generally need to support software updates. On a continuum from "general purpose" to "embedded", large application systems will have subcomponents at most points even if the system as a whole is "designed to perform one or a few dedicated functions", and is thus appropriate to call "embedded".
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Variety of embedded systems
PC Engines' ALIX.1C Mini-ITX Mini-ITX is a 17 x 17 cm low-power motherboard form factor developed by VIA Technologies. Mini-ITX is slightly smaller than microATX. Mini-ITX boards can often be passively cooled due to their low power consumption architecture, which makes them useful for home theater systems, where fan noise can detract from the cinema experience embedded board with an x86 AMD Geode Geode is a series of x86-compatible system-on-a-chip microprocessors and I/O companions produced by AMD targeted at the embedded computing market LX 800 together with Compact Flash CompactFlash is a mass storage device format used in portable electronic devices. For storage, CompactFlash typically uses flash memory in a standardized enclosure, miniPCI and PCI slots, 22-pin IDE Parallel ATA is an interface standard for the connection of storage devices such as hard disks, solid-state drives, and CD-ROM drives in computers. The standard is maintained by X3/INCITS committee. It uses the underlying AT Attachment and AT Attachment Packet Interface (ATA/ATAPI) standards interface, audio, USB and 256MB RAM An embedded RouterBoard 112 with U.FL U.FL, is a miniature coaxial RF connector for high-frequency signals up to 6 GHz manufactured by Hirose Electric Group in Japan. U.FL connectors are commonly used inside laptops and embedded systems to connect the Wi-Fi antenna to a Mini PCI card. Female U.FL connectors are not designed with reconnection in mind, and they are only rated for a few-RSMA SMA connectors are coaxial RF connectors developed in the 1960s as a minimal connector interface for coaxial cable with a screw type coupling mechanism. The connector has a 50 Ω impedance. It offers excellent electrical performance from DC to 18 GHz pigtail and R52 miniPCI Wi-Fi Wi-Fi is a trademark of the Wi-Fi Alliance that manufacturers may use to brand certified products that belong to a class of wireless local area network (WLAN) devices based on the IEEE 802.11 standards, which is by far the most widespread WLAN class today. Because of the close relationship with its underlying standards, the term Wi-Fi is often card widely used by wireless Wireless communication is the transfer of information over a distance without the use of enhanced electrical conductors or "wires". The distances involved may be short or long (thousands or millions of kilometers for radio communications). When the context is clear, the term is often shortened to "wireless". Wireless Internet The Internet is a global system of interconnected computer networks that use the standard Internet Protocol Suite to serve billions of users worldwide. It is a network of networks that consists of millions of private, public, academic, business, and government networks of local to global scope that are linked by a broad array of electronic and service providers (WISPs Wireless Internet Service Providers are Internet service providers with networks built around wireless networking. Technology may include commonplace Wi-Fi wireless mesh networking, or proprietary equipment designed to operate over open 900MHz, 2.4GHz, 4.9, 5.2, 5.4, and 5.8GHz bands or licensed frequencies in the UHF or MMDS bands) in the Czech Republic The Czech Republic (pronounced /ˈtʃɛk/ chek; Czech: Česká republika, pronounced [ˈtʃɛskaː ˈrɛpuˌblɪka] ( listen), short form Česko [ˈtʃɛskɔ]) is a landlocked country in Central Europe. The country borders Poland to the northeast, Germany to the west and northwest, Austria to the south and Slovakia to the east. The Czech Republic.Embedded systems span all aspects of modern life and there are many examples of their use.
Telecommunications systems employ numerous embedded systems from telephone switches In the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls. A central office is the physical building used to house inside plant equipment including telephone switches, which make telephone calls "work" in the sense of making connections and relaying the for the network to mobile phones A mobile phone is an electronic device used for full duplex two-way radio telecommunications over a cellular network of base stations known as cell sites. Mobile phones differ from cordless telephones, which only offer telephone service within limited range through a single base station attached to a fixed land line, for example within a home or at the end-user. Computer networking uses dedicated routers A router is an electronic device that interconnects two or more computer networks, and selectively interchanges packets of data between them. Each data packet contains address information that a router can use to determine if the source and destination are on the same network, or if the data packet must be transferred from one network to another and network bridges Bridging is a forwarding technique used in packet-switched computer networks. Unlike routing, bridging makes no assumptions about where in a network a particular address is located. Instead, it depends on flooding and examination of source addresses in received packet headers to locate unknown devices. Once a device has been located, its location to route data.
Consumer electronics Consumer electronics include electronic equipment intended for everyday use. Consumer electronics are most often used in entertainment, communications and office productivity. Some products classed as consumer electronics include personal computers, telephones, MP3 players, audio equipment, televisions, calculators, GPS automotive navigation include personal digital assistants The term PDA was first used on January 7, 1992, by Apple Computer CEO John Sculley at the Consumer Electronics Show in Las Vegas, Nevada, referring to the Apple Newton. In 1996, Nokia introduced the first mobile phone with full PDA functionality, the 9000 Communicator, which has since grown to become the world's best-selling PDA and which spawned (PDAs), mp3 players A digital audio player, shortened to DAP, usually referred to as an MP3 player, is a consumer electronic device that has the primary function of storing, organizing and playing audio files, in contrast to physical medium audio players, which play music from a physical medium on which the audio files are mechanically or electronically printed, mobile phones, videogame consoles, digital cameras A digital camera is a camera that takes video or still photographs, or both, digitally by recording images via an electronic image sensor, DVD players A DVD player is a device that plays discs produced under both the DVD-Video and DVD-Audio technical standards, two different and incompatible standards, GPS The Global Positioning System is a space-based global navigation satellite system that provides reliable location and time information in all weather and at all times and anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites. It is maintained by the United States government and is freely receivers, and printers In computing, a printer is a peripheral which produces a hard copy of documents stored in electronic form, usually on physical print media such as paper or transparencies. Many printers are primarily used as local peripherals, and are attached by a printer cable or, in most newer printers, a USB cable to a computer which serves as a document. Many household appliances, such as microwave ovens A microwave oven, or a microwave, is a kitchen appliance that cooks or heats food by dielectric heating. This is accomplished by using microwave radiation to heat water and other polarized molecules within the food. This excitation is fairly uniform, leading to food being more evenly heated throughout than generally occurs in other cooking, washing machines A clothes washer, or washer, is a machine designed to wash laundry, such as clothing, towels and sheets. The term is mostly applied only to machines that use water as the primary cleaning solution, as opposed to dry cleaning or even ultrasonic cleaners and dishwashers A dishwasher is a mechanical device for cleaning dishes and eating utensils. Dishwashers can be found in restaurants and private homes, are including embedded systems to provide flexibility, efficiency and features. Advanced HVAC HVAC is an initialism that stands for the closely related functions of "Heating, Ventilating, and Air Conditioning"—the technology of indoor or automotive environmental comfort. HVAC system design is a major subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer systems use networked thermostats A thermostat is a device for regulating the temperature of a system so that the system's temperature is maintained near a desired setpoint temperature. The name is derived from the Greek words thermos "hot" and statos "a standing". The thermostat does this by switching heating or cooling devices on or off, or regulating the to more accurately and efficiently control temperature that can change by time of day and season A season is a division of the year, marked by changes in weather, ecology, and hours of daylight. Home automation Home automation designates an emerging practice of increased automation of household appliances and features in residential dwellings, particularly through electronic means that allow for things impracticable, overly expensive or simply not possible in recent past decades. The term may be used in contrast to the more mainstream "building uses wired- and wireless-networking that can be used to control lights, climate, security, audio/visual, surveillance, etc., all of which use embedded devices for sensing and controlling.
Transportation systems from flight to automobiles increasingly use embedded systems. New airplanes contain advanced avionics Avionics is a blend of the words "aviation" and "electronics". It comprises electronic systems for use on aircraft, artificial satellites and spacecraft, comprising communications, navigation and guidance, display systems, flight management systems, sensors and indicators, weather radars, electrical systems and various other such as inertial guidance systems An Inertial Navigation System is a navigation aid that uses a computer, motion sensors (accelerometers) and rotation sensors (gyroscopes) to continuously calculate via dead reckoning the position, orientation, and velocity (direction and speed of movement) of a moving object without the need for external references. It is used on vehicles such as and GPS The Global Positioning System is a space-based global navigation satellite system that provides reliable location and time information in all weather and at all times and anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites. It is maintained by the United States government and is freely receivers that also have considerable safety requirements. Various electric motors — brushless DC motors A brushless DC motor is a synchronous electric motor powered by direct-current (DC) electricity and having an electronic commutation system, rather than a mechanical commutator and brushes. In BLDC motors, current to torque and voltage to rpm are linear relationships, induction motors An induction motor or asynchronous motor is a type of alternating current motor where power is supplied to the rotor by means of electromagnetic induction and DC motors — are using electric/electronic motor controllers. Automobiles, electric vehicles, and hybrid vehicles are increasingly using embedded systems to maximize efficiency and reduce pollution. Other automotive safety systems include anti-lock braking system (ABS), Electronic Stability Control (ESC/ESP), traction control (TCS) and automatic four-wheel drive.
Medical equipment is continuing to advance with more embedded systems for vital signs monitoring, electronic stethoscopes for amplifying sounds, and various medical imaging (PET, SPECT, CT, MRI) for non-invasive internal inspections.
In addition to commonly described embedded systems based on small computers, a new class of miniature wireless devices called motes are quickly gaining popularity as the field of wireless sensor networking rises. Wireless sensor networking, WSN, makes use of miniaturization made possible by advanced IC design to couple full wireless subsystems to sophisticated sensors, enabling people and companies to measure a myriad of things in the physical world and act on this information through IT monitoring and control systems. These motes are completely self contained, and will typically run off a battery source for many years before the batteries need to be changed or charged.
History
In the earliest years of computers in the 1930–40s, computers were sometimes dedicated to a single task, but were far too large and expensive for most kinds of tasks performed by embedded computers of today. Over time however, the concept of programmable controllers evolved from traditional electromechanical sequencers, via solid state devices, to the use of computer technology.
One of the first recognizably modern embedded systems was the Apollo Guidance Computer, developed by Charles Stark Draper at the MIT Instrumentation Laboratory. At the project's inception, the Apollo guidance computer was considered the riskiest item in the Apollo project as it employed the then newly developed monolithic integrated circuits to reduce the size and weight. An early mass-produced embedded system was the Autonetics D-17 guidance computer for the Minuteman missile, released in 1961. It was built from transistor logic and had a hard disk for main memory. When the Minuteman II went into production in 1966, the D-17 was replaced with a new computer that was the first high-volume use of integrated circuits. This program alone reduced prices on quad nand gate ICs from $1000/each to $3/each[citation needed], permitting their use in commercial products.
Since these early applications in the 1960s, embedded systems have come down in price and there has been a dramatic rise in processing power and functionality. The first microprocessor for example, the Intel 4004, was designed for calculators and other small systems but still required many external memory and support chips. In 1978 National Engineering Manufacturers Association released a "standard" for programmable microcontrollers, including almost any computer-based controllers, such as single board computers, numerical, and event-based controllers.
As the cost of microprocessors and microcontrollers fell it became feasible to replace expensive knob-based analog components such as potentiometers and variable capacitors with up/down buttons or knobs read out by a microprocessor even in some consumer products. By the mid-1980s, most of the common previously external system components had been integrated into the same chip as the processor and this modern form of the microcontroller allowed an even more widespread use, which by the end of the decade were the norm rather than the exception for almost all electronics devices.
The integration of microcontrollers has further increased the applications for which embedded systems are used into areas where traditionally a computer would not have been considered. A general purpose and comparatively low-cost microcontroller may often be programmed to fulfill the same role as a large number of separate components. Although in this context an embedded system is usually more complex than a traditional solution, most of the complexity is contained within the microcontroller itself. Very few additional components may be needed and most of the design effort is in the software. The intangible nature of software makes it much easier to prototype and test new revisions compared with the design and construction of a new circuit not using an embedded processor.
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