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EMBEDDED COMPUTING - INTRODUCTION
An embedded system is a special-purpose computer system designed to perform a dedicated function Unlike a general-purpose computer, such as a personal computer, an embedded system performs one or a few pre-defined tasks, usually with very specific requirements, and often includes task-specific hardware and mechanical parts not usually found in a general-purpose computer.
Embedded computer System: Any device that includes a programmable computer but is not itself intended to be a general-purpose computer is called embedded computer system.
Computers have been embedded into applications since the earliest days of computing.Eg) Whirlwind. a computer designed at MIT in the late 1940s and early 1950s. Whirlwind was also the first computer designed to support real-time operation and was originally conceived as a mechanism for controlling an aircraft simulator.
A microprocessor is a single-chip CPU. The first microprocessor, the Intel 4004, was designed for an embedded application, namely, a calculator. Microprocessors come in many different levels of sophistication; they are usually classified by their word size. Microprocessors execute programs very efficiently.
An 8-bit microcontroller is designed for low-cost applications and includes on-board
memory and I/O devices;
A 16-bit microcontroller is often used for more sophisticated applications that may require either longer word lengths or off-chip I/O and memory;
A 32-bit RISC microprocessor offers very high performance for computation-intensive applications.
Why use microprocessors?
ü Microprocessors are a very efficient way to implement digital systems.
ü Microprocessors make it easier to design families of products that can be built to provide various feature sets at different price points and can be extended to provide new features to keep up with rapidly changing markets.
Ø Characteristics of Embedded Computing Applications
Embedded computing is in many ways much more demanding than the sort of programs that you may have written for PCs or workstations. On the one hand, embedded computing systems have to provide sophisticated functionality:
■ Complex algorithms: The operations performed by the microprocessor may be very sophisticated. For example, the microprocessor that controls an automobile engine must perform complicated filtering functions to optimize the performance of the car while minimizing pollution and fuel utilization.
■ User interface: Microprocessors are frequently used to control complex user interfaces that may include multiple menus and many options. The moving maps in Global Positioning System (GPS) navigation are good examples of sophisticated user interfaces.
■ Real time: Many embedded computing systems have to perform in real time if the data is not ready by a certain deadline, the system breaks. In some cases, failure to meet a deadline is unsafe and can even endanger lives. In other cases, missing a deadline does not create safety problems but does create unhappy customers—missed deadlines in printers, can result in scrambled pages.
■ Multirate: Many embedded computing systems have several real-time activities going on at the same time. They may simultaneously control some operations that run at slow rates and others that run at high rates. Multimedia applications are prime examples of multirate behavior. The audio and video portions of a multimedia stream run at very different rates, but they must remain closely synchronized.
Costs of various sorts are also very important:
■ Manufacturing cost: The total cost of building the system is very important in many cases. Manufacturing cost is determined by many factors, including the type of microprocessor used, the amount of memory required, and the types of I/O devices.
■ Power and energy: Power consumption directly affects the cost of the hardware, since a larger power supply may be necessary. Energy consumption affects battery life, which is important in many applications,as well as heat consumption, which can be important even in desktop applications.
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