This essay has been submitted by a student. This is not an example of the work written by our professional essay writers.
An embedded system is a computer system designed to perform one or a few dedicated functions often with real time computing constraints. It is embedded as part of complete device often including hardware and mechanical parts. By contrast, a general purpose computer , such as a personal computer , is designed to be flexible and to meet a wide range of end-user needs. Embedded system control many devices in common use today.
Embedded system is controlled by one or more main processing cores that are typically either microcontrollers or digital signal processors. The key characteristic, however, is being dedicated to handle a particular task, which may require very powerful processors. For example, air traffic control systems may usefully be viewed as embedded, even though they involve mainframe computers and dedicated regional and national networks between airports and radar sites.
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.
Physically, embedded systems range from portable devices such as digital watches and MP3 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 strictly definable term, as most systems have some element of programmability. For example handheld computers share some elements with embedded system such as the operating system and microprocessors which power them. But they allow different applications to be loaded and peripharals to be connected. In "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 thus appropriate to call "embedded".
IMPLEMENTATION OF HOME APPLIANCES
Here I am going to concentrate on digital camera,
Typically, embedded systems are reactive and real time systems. A reactive system is one, which is in continual interaction with its environment and executes at a pace determined by that environment.
ISA bus interface
The charge coupled device contains an array of light sensitive photocells that capture an image. The A2D and D2A circuits convert analog images to digital and digital to analog. The CCD preprocessor provides commands to the CCD to read the image. The JPEG CODEC compresses and decompresses an image using the JPEG compression standard, enabling compact storage of images in the limited memory of camera. The pixel coprocessor aids in rapidly displaying the image. The memory controller controls access to a memory chip, while the DMA controller enables direct memory access by other devices while the microcontroller is performing other functions. The URAT enables communications with a PC's serial port for uploading video frames, while ISA bus interface enables a faster connection with a PC's ISA bus. The LCD control and display control circuits controls the display of images of the cameras LCD device. The multiplier/accumulator circuit performs a particular frequently executed computation faster than the microcontroller could. At the heart of the system is the microcontroller, a programmable processor that controls the activities of all the other circuits and each device as a processor designed for particular task.
The characteristics of the above example embedded system,
It performs the function repeatedly
The system always acts as camera wherein it captures, compresses, stores frames, decompresses and display frames and uploads frames.
It is tightly constrained
It must be low cost, fast and small in size.
PROGRAMMING LANGUAGE USED
C is one of the most commonly used programming language in embedded devices, because software written in a language like C is used to control the mechanical devices within the embedded system.
Reasons C Is Common In Embedded Systems
C is one of the most commonly used software languages used on embedded device controllers. One reason is because it is one of the few software languages that operate on both 8 bit controllers and 64 bit PCs that means many computer programmers can write C software for both personal computers and embedded devices. The C language can also use very simple commands to control the device, freeing up the limited memory of the device to whole many commands or parameters. C can be written for both microcontrollers and digital signal processors.
C Languages Used In Embedded Systems
C and C++ are used frequently in creation of embedded systems. Embedded systems are rarely programmed using the C++ because embedded systems rarely have the memory space for the complex programming used in C++. C# is occasionally used on embedded Linux systems.
How C Programs Are Created And Installed On Embedded Systems
Code is written in C on a programmers PC. Code is run through a complier on the programmers PC to create a software program. The embedded system software may be run through a simulator on the programmer's computer. The software program is copied onto the controller using "programmer". The controller is then tested on a "test bed" to ensure that it works properly.
Common Embedded Systems That Use C
Bluetooth device are programmed in C. PIC microcontrollers such as those used in web cameras are frequently programmed in C. PIC microcontrollers programmed in C have also been used in LED devices and LCD monitors. USB devices are embedded devices frequently coded in C.
Standards For Embedded System Programming In C
The American national standards institute has written standards for the C programming language. The international standards organization wrote standards ISO.IEC 9899 for the C programming language. The motor industry software reliability association has created a proprietary set of standards for programming in C for embedded devices in automobiles.
EMBEDDED SYSTEM APPLICATION
Transportation system from flight to automobiles increasingly uses embedded systems. New airplanes contain advanced avionics such as inertial guidance systems and GPS receivers that also have considerable safety requirements. Various electric motors that are brushless DC motors, induction motors 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, electronic stability control, transaction control and automatic four-wheel drive.
Embedded system systems are especially suited for use in transportation, fire safety and security, medical applications and life critical systems as these systems can be isolated from hacking and thus be more reliable. For fire safety, the systems can be designed to having greater ability to handle higher temperatures and continue to operate. In dealing with security, the embedded systems can be self sufficient and be able to deal with cut electrical and communication systems.