Introduction to embedded system

Introduction to embedded system

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  Embedded Systems - Introduction By, Mrs.S.Revathi
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  UNIT I INTRODUCTION TOEMBEDDED SYSTEMS • Introduction to Embedded Systems • The build process for embedded systems • Structural units in Embedded processor • selection of processor & memory devices • DMA • Memory management methods • Timer and Counting devices • Watchdog Timer • Real Time Clock • In circuit emulator • Target Hardware Debugging
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  Definition “An embedded systemis a system that has embedded software in a computer hardware. The system is dedicated for either an application(s) or specific part of an application or product or a component of a large system.”
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  Components • It embedshardware similar to a computer. the processer may be embedded processor cores. The hardware includes embedded memory, peripheral and input-output devices. It embeds main application software which may perform concurrently multiple tasks. • Software usually embeds in the ROM, flash memory or media card. Does not have secondary hard disk or CD memory as in computer. • It embeds real time operating system(RTOS). It supervises the application software and controls the access to system resources.
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  Characteristics • Program ispreloaded or embedded in the ROM or flash memory. • System functions in real time. • Task executes according to priorities. • The system reacts to the events, interrupts in predetermined time interval and schedules responses according to priorities. • System controls the latencies of tasks, events and then interrupts and responds. • Latency means time interval between the instance of need to respond and start of the actual execution. • Dedicated set of functions • Complex dedicated –purpose algorithms • Complex dedicated –purpose preprogrammed hardware and graphic and other user interfaces • Multirate operations with different predetermined time constraints, to finish the different operations.
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  Constraints • Available systemmemory • Available processor speed • Requirement for the system to run continuously and therefore, the system needs to limit power dissipation while running • System design for an embedded system has constraints of performance, power, size and the design and manufacturing costs.
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  Processor embedded intoa system • Processor is an important unit in any computing system • It is the heart of the embedded system • The instructions, defined in the instrument set of a processor, arrange in a sequence in a program. • The program executes in the sequence of their fetch from the memory. • Processor has two essential units: Program Flow Control Unit and Execution unit • The processor runs the cycles of fetch and execution of a set of instructions.
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  Processor chip orcore in an embedded system can be one of the following: • Microprocessor (or) Embedded Processor • Application Specific Instruction-Set Processor (ASIP) • Single-Purpose Processor as an Additional Processor
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  Build Process forEmbedded Systems • An embedded system develops using process of designing the hardware, target platform and software followed by integrating both. • The first step in the build process for an embedded system hardware consists of selecting a processor. • A processor is selected from the considerations of the following: Instruction set Maximum bits in an operand in a single arithmetic or logical expression
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  Clock frequency inMHz or GHz and processing speed in Million Instructions Per Second (MIPS) Processing ability to solve the complex algorithm using in meeting the deadlines for their processing. • The build process for embedding software consists of the following steps: 1. Project file consisting of source file and library files 2. Compilation of the project files 3. Linking all object files and locating onto a single re- locatable object file 4. Converting the object file in a form called hex-file to binary image (ROM image)
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  Build Process---Process Embedding Microprocessor–Each microprocessor has an instruction set. Programs written in high-level language are compiled. A compiler generates the executable codes. Executable code file loads into RAM and runs using the processor.
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  • Embedding Microcontroller—Eachmicrocontroller has an instruction set which includes instructions, which enable use of the devices and peripherals. Programs are compiled. Embedded software actions are simulated. The system software is debugged to trace the errors. Flash is programmed using the tested codes.
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  Embedded Hardware unitsand devices in a System Building Blocks:  Power Source  Clock Oscillator and Clocking units  System timer  Real Time Clock  Reset circuit, Power-up Reset and Watchdog-timer reset  Memory  Input, output and I/O ports, I/O buses and I/O interfaces  Bus  DAC  ADC  LED,LCD and Touch-Screen Displays  Keyboard, keypad or virtual keypad at touch screen  Interrupt handler
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  THANK YOU…