Definition: An embedded system is a combination of hardware and
software which creates a dedicated computer system that performs specific, pre-defined
tasks and which is encapsulated within the device it controls (if it is part
of a larger device).
Embedded systems can be found in an enormous range of electrical items ranging from simple, inexpensive
products such as digital watches to expensive, complex products such as automobiles.
Features of Embedded Systems
The versatility of the embedded computer system lends itself to utility in all kinds of enterprises, from the
simplification of deliverable products to a reduction in costs in their development and manufacture.
Simplification, Miniaturisation and Cost Reduction
Embedded systems are designed to perform simple, repeatable tasks - often with little or no input
from the user. Since the first microprocessor was introduced into pocket calculators there has been a
concerted drive to reduce the size and complexity of computerised systems in electronic devices.
Embedded systems are based on the concept of the microcontroller, a single integrated circuit that
contains all the technology required to run an application. Microcontrollers make integrated systems
possible by combining several features together into what is effectively a complete computer on a chip, including:
* Central Processing Unit
* Input/Output interfaces (such as serial ports)
* Peripherals (such as timers)
* ROM, EEPROM or Flash memory for program storage
* RAM for data storage
* Clock generator
By integrating all of these features into a single chip it is possible to greatly reduce the number
of chips and wiring necessary to control an electronic device, dramatically reducing its complexity,
size and cost.
Uses of Embedded Systems
There are endless uses for embedded systems in consumer products, with new methods of exploiting them
presented every year at such industry events as the MEDC and the Embedded Systems Conference. The most
obvious beneficiaries are those enterprises concerned with the manufacture and sale of electrical devices,
as the inclusion of microcontrollers to replace general purpose microprocessors can drive down unit
manufacturing costs and end user prices dramatically, resulting in increased sales and an improved profit margin.
The use of embedded systems in electrical products can also solve many problems of complexity and
product size. For example, a modern automobile may contain dozens of embedded systems to control a
wide range of processes within the car, ranging from brake balance control to air conditioning to the
ignition system. Without embedded systems it would be impossible to computerise all of these features
without the inclusion of a mass of complicated, fault prone electronics.
The only realistic alternative to using embedded systems in a modern automobile would be to install a
fully functional PC within the car to control all of the functions currently managed by microcontrollers.
While this may be feasible it would raise several issues:
* Size & Weight:
Microcontrollers are designed to deliver maximum performance for minimum size and weight. A
centralised on-board computer system would greatly outweigh a collection of microcontrollers.
Microcontrollers are designed to perform repeated functions for long periods of time without
failing or requiring service. Other computer systems are prone to software and hardware failure
as well as a whole host of other problems recognisable to the users of any home computer. Above
all other considerations, computer systems must be 100% reliable when trusted to control such
functions as braking in an automobile.
Downfalls of Embedded Systems
There are, however, several downfalls to embedded technology. When problems develop with a
personal computer the manufacturers can develop and release a software patch to their customers,
who can then rectify the problem themselves. Problems with embedded systems, however, are more
difficult to fix. Embedded systems are not designed for user interaction, so the majority of
embedded systems are just that – embedded within the product, with no easy method of updating or repairing their software.
Since embedded systems are often used to control such functions as braking in an automobile or
the guidance system on an intercontinental missile they cannot be released onto the market before
they have been extensively tested and retested. Quite simply, there can be no margin of error. As
a result the cost of embedded systems can often be deceptively high. While the manufacturing costs
are reduced, the testing and quality control costs can be higher than expected.
With advances in technology these drawbacks are steadily becoming less important, and industry expert
organisations such as the Embedded Systems Institute, the
National Science Foundation and
work steadily to minimise the difficulties associated with the use of Embedded Systems.