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INTRODUCTION
1.1 EMBEDDED SYSTEM
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. Since the system is dedicated to specific tasks, design engineers can optimize it, reducing the size and cost of the product. Embedded system comprises of both hardware and software. Embedded system is fast growing technology in various fields like industrial automation, home appliances, automobiles, aeronautics etc.
Embedded technology is implemented to perform a specified task and the programming is done using assembly language programming or embedded C. Ours being a developing country the power consumption is increasing on large scale to meet the growing need of the people. Power generation is widely based on the non-renewable sources and these sources being depleting some means have to be found for power saving.
Physically, embedded systems ranges 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.
In terms of complexity embedded systems can range from very simple with a single microcontroller chip, to very complex with multiple units, peripherals and networks mounted inside a large chassis or enclosure.
1.2 Examples of Embedded Systems:
• Avionics, such as inertial guidance systems, flight control hardware/software and other integrated systems in aircraft and missiles
• Cellular telephones and telephone switches
• Engine controllers and antilock brake controllers for automobiles
• Home automation products, such as thermostats, air conditioners, sprinklers, and security monitoring systems
• Handheld calculators
• Handheld computers
• Household appliances, including microwave ovens, washing machines, television sets, DVD players and recorders
• Medical equipment
• Personal digital assistant
• Videogame consoles
1.3 CHARACTERISTICS OF EMBEDDED SYSTEM:
• It is very reactive and real time constrained.
• Increasingly high performance.
• Application specific processor design can be significant component of
embedded system.
• It acts as a single function not used as general purpose.
1.4 Requirement of Embedded System
 Functional Requirement
• Direct digital control.
• Data collection.
• Man-machine interaction
 Temporal Requirement
• Tasks may have dead lines
• Minimal error detection latency
• Timing requirement
• Human-interface requirements.
 Dependability Requirement
• Reliability
• Safety
• Availability
• Maintainability
• Security
1.5 Block diagram of Embedded System
Fig 1.5 Block diagram of Embedded System
 Processor:
• A Processor is a digital circuit designed to perform computational tasks.
• An Embedded system consists of single purpose processor rather than general purpose processor.
• Single purpose processor better then general-purpose processor.
 ASICs(Application Specific ICs)
• It is the silicon chip with an array of unconnected transistors.
• It includes gate arrays and standard cell ICs.
 Memory
• A fixed size volatile memory such as DRAM or SRAM & non-volatile memory such as EPROM or Flash, connected to microcontroller/processor is used.
 Peripherals:
• According to the block diagram analog I/O consists of the several peripherals according to the requirement or the application. some of the peripherals are listed below:
• Timer, counter
• UART
• Pulse Width Modulators
• LCD controller
• DMA controller
• Keypad controller
• Stepper motor controller
• ADC converter
• Real Time clock
 Assembly Language:
• It is made up of set on mnemonics.
• Each mnemonics corresponds directly to the processor machine instruction code.
 C Language:
• As it is high level language it is shorter and easier to write.
• It is independent of the processor.
• It is used most frequently than Assembly language.
• C languages as two important advantages, because of which it is much easier for programmer to write quality programs that are easier to read, revise and port to a different system.
• Built-in structure
• Checking and Abstraction.