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ABSTRACT
“Embedded systems have virtually entered every sphere of our lives”
Embedded systems encompass a variety of hardware and software components, which perform specific functions in host systems, for example, satellites, washing machines, hand-held telephones and automobiles. Embedded systems have become increasingly digital with a non-digital periphery (analog power) and therefore, both hardware and software co-design are relevant. The vast majority of computers manufactured are used in such systems. They are called `embedded' to distinguish them from standard mainframes, workstations, and PCs. Although the design of embedded systems has been used in industrial practice for decades, the systematic design of such systems has only recently gained increased attention. Advances in microelectronics have made possible applications that would have been impossible without an embedded system design.
Embedded System Applications describes the latest techniques for embedded system design in a variety of applications. This also includes some of the latest software tools for embedded system design. Embedded System Applications will be of great interest to researchers and designers working in the design of embedded systems for industrial applications.
Embedded systems have virtually entered every sphere of our lives, right from the time we work out on trade mills in the gym, to the cars we drive today. Embedded systems cover a broad range of products that generalization is difficult.
INTRODUCTION:
Breathtaking developments in microelectronics, processor speeds, and memory elements, accompanied with dropping prices, have resulted in powerful embedded systems with a number of applications.
An embedded system is a microprocessor –based system that is incorporated into a device to monitor and control the functions of the components of the device. They are used in many devices ranging from a microwave oven to a nuclear reactor. Unlike personal computers that run a variety of applications, embedded systems are designed for performing specific tasks. An embedded system used in a device (for instance the embedded system in washing machine that is used to cycle through the various states of the washing machine) is programmed by the designers of the system and generally cannot be programmed by the end user.
Definition :
An embedded system is various type of computer system or computing device that performs a dedicated function and/or is designed for use with a specific embedded software application.
Embedded systems posses the following distinguishing qualities.
Reliability:
Embedded system should be very reliable as they perform critical functions. For instance, consider the embedded system used for flight control. Failure of the embedded system could have disastrous consequences. Hence embedded system programmers should take into consideration all possibilities and write programs that do not fail.
Responsiveness:
Embedded systems should respond to events as soon as possible. For example, a patient monitoring system should process the patient’s heart signals quickly and immediately notify if any abnormality in the signals is detected.
Specialized hardware:
Since embedded systems are used for performing specific functions, specialized hardware is used. For example, embedded systems that monitor and analyze audio signals use signal processors.
Low cost:
As embedded systems are extensively used in consumer electronic systems, they are cost sensitive. Thus their cost must be low.
Robustness:
Embedded systems should be robust since they operate in a harsh environment. They should endure vibrations, power supply fluctuations and excessive heat.
EMBEDDED SYSTEM AND REAL TIME SYSTEM:
Embedded systems are confused with real-time systems. A real time system is one in which the correctness of the computations not only depends on the accuracy of the result, but also on the time when the result is produced. Figure 1 shows the relationship between embedded and real time systems.
Fig: Embedded And real-time systems
COMPONENTS OF AN EMBEDDED SYSTEM:
Embedded systems have the following components.
PROCESSOR:
A processor fetches instructions from the memory unit and executes the instructions. An instruction consists of an instruction code and the operands on which the instruction should act upon. The format of instruction code and operands of a processor is defined by the processor’s instruction set. Each type of processor has its own instruction set. Performance of the system can be improved by dedicated processors, which implement algorithms in hardware using building blocks such as hardware counters and multipliers.
Some embedded processors have special fuzzy logic instructions. This is because inputs to an embedded system are sometimes better represented as fuzzy variables. For instance, the mathematical model for a control system may not exist or may involve expensive computing power. Fuzzy logic can be employed for such control systems to provide a cost-effective solution.
MEMORY:
The memory unit in an embedded system should have low access time and high density. (A memory chip- has greater density if it can store more bits in the same amount of space. Memory in an embedded system consists of ROM and RAM .The contents of ROM are non-volatile while RAM is volatile. ROM stores the program code while RAM is used to store transient input or output data. Embedded systems generally do not possess secondary storage devices such as magnetic disks. As programs of embedded systems are small there is no need of virtual storage.