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Embedded systems   in brief
 

Embedded systems in brief

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    Embedded systems   in brief Embedded systems in brief Presentation Transcript

    • A Brief Introduction to Embedded Systems K. Raghunathan Chartered Engineer FIETE, MIE, MCSI, MISTE, MISTD. MIIMM Retd. Dy. Controller (R&D)
    • Embedded Systems
      • Overview of Embedded Systems
      • Embedded System Design
      • Embedded System Designer
      • More Knowledge
    • Overview of Embedded Systems
      • What is an Embedded System ?
      • Examples of Embedded Systems
      • Why an “Embedded” System ?
      • Salient Features
    • What is an Embedded System ?
      • A computer system, fitted as part of some Equipment which is not a computer
      • The whole system is not called a computer - it is known by the name of the Equipment
      • The embedded computer system controls the equipment in which it is embedded
      • Performs only specific tasks, often in real-time
    • Examples of Embedded Systems
      • Network Printer
        • Network Interfacing & Routing
      • Handheld Barcode Scanner
        • Conversion of Image to Number
      • Mobile Phone with Internet Connectivity
        • Browsing, eMail, FTP, Chat etc
    • Examples of Embedded Systems
      • CNC Machines & Robots
        • Control the Sequence of Operations
      • Satellites
        • Remote-sensing, Data-formatting, Communication, Navigation Control etc
      • Televison Set
        • Digital on-screen display of menu, channel number, subtitles etc
      • Washing Machines
        • Control of Sequence of Operations, Motor speed & duration control etc
    • Why “embed” a Computer ?
      • Computers are more suitable for
        • Control
        • Data Processing
        • Decision Making
        • Digital Communication
    • Why “embed” a Computer ?
      • Main Equipment is Larger & Costlier; computer is smaller, cheaper & used for only some specific purpose
      • Using General-purpose computer involves additional space & wiring. It is better to fit a small computer inside [or onto] the equipment itself
      • often, main equipment itself may have to be small & portable
    • Salient Features of Embedded Systems
      • Purpose & Functionality
        • Specific Purpose; Limited Functionality
      • Size
        • Small enough to fit into/onto the main eqpt
      • Real-Time
        • Response within a specified Time-limit
      • I/O Devices
        • Very Few; only a set of Sensors & Activators
        • Conspicuous absence of conventional devices like keyboard, CRT screen, hard disk etc
    • Embedded Systems
      • Overview of Embedded Systems
      • Embedded System Design
      • Embedded System Designer
      • More Knowledge
    • Embedded System Design
      • Selection of CPU & other Hardware
      • Design of the Hardware System
      • Design & Development of Software
      • Testing & Debugging
      • Loading the Software into the Embedded System’s Memory
    • Selection of CPU & other Hardware
      • CPU
        • Speed
        • Instruction Set
        • Multitasking Capabilities
        • Interrupt- handling Capabilities
        • Power Consumption
        • Heat Dissipation
    • Memory
      • Non-Volatile [ROM/PROM/EPROM]
        • Code
        • Fixed Data
          • Look-Up Tables, Constants, Initial Values of Variables
      • Volatile [RAM]
        • Variable Data
        • temporary data
    • I/O Devices
      • Depends on :
        • Main Equipment & its purpose/functions
        • Purpose to be served by the embedded system
      • May also need :
        • HW & SW Interfaces or Drivers for the i/o devices
    • Software Development
      • Software has to be developed on some other convenient computer system [ Host System ]
      • The Code obtained in the Host system should run in the Embedded System [ Target System ]
    • Software Development
      • HW configuration of Host & Target will be different
      • Should use Cross Compilers & Cross Assemblers on the Host, to get Target System’s Machine Code as the Output
      • Often, an RTOS [Real Time Operating System] is used
    • Software Development
      • Usually the SW is developed as a set of Tasks [functions/procedures] & ISRs [Interrupt Service Routines]
      • Tasks perform some specific actions
        • most likely, some of the primary functions of the Main eqpt
      • ISRs interrupt running Tasks based on certain events [inputs from sensors]
        • to take appropriate action for those inputs
        • to update data for the tasks
    • Testing & Debugging
      • Often not possible to test the program by actually loading it into the target system & running it in the Main eqpt
      • So, code has to be tested in the Host system itself
      • Need Emulators which can emulate the embedded system’s CPU
    • Testing & Debugging
      • Drivers & Scaffolds to be written
        • to simulate actual inputs & behaviour of the main eqpt
      • Test Data
        • normally expected range of values
        • out-of-range values
        • erroneous data
    • Loading SW in the Embedded System’s Memory
      • No operating system in the embedded system
      • Code generated on the Host system should include start-up [initialising] routines for the target system
      • Use of RTOS ensures automatic addition of start-up code
    • Loading SW in the Embedded System’s Memory
      • Special programs called Locators enable developer to specify which blocks of code should be loaded at what addresses in the embedded system’s memory
      • Output of Locator is in the form of a file stored in the Host; this file will have a special format [not the standard executable file you get in desktop systems]
      • Special programs called Loaders
        • understand the Locator’s file format
        • load the code in embedded systems memory
    • Tools for Embedded Software Development
      • Cross Compilers
      • Cross Assemblers
      • Locators
      • RTOS
      • Loaders
    • RTOS
      • Easier Development Environment
      • Produce Machine Code of Target CPU
      • Automatic inclusion of Start-up Code
      • Many RTOSes available
        • iRMX86, uC-OS, VxWorks, pSOS, QNX etc
      • Many of them written in C/C++
        • allow us to develop programs using C/C++
    • RTOS
      • Main Features
        • Multi-tasking
        • Task Scheduling Policies
        • Mutual Exclusion using Semaphores
        • Message Queues, Mailboxes and/or Pipes for Inter-Process Communication
    • Hardware Design Considerations
      • Physical Size
        • Small
      • Power Consumption
        • Low
      • Heat Dissipation
        • Very Low
      • Cost
        • Low cost, without compromising Quality & Performance
    • Software Design Considerations
      • Real Time Response
        • No part of the code can take unpredictable execution time
        • ISRs must be kept short
        • No Dead-Locks or Circular Waits
      • Reliability
        • Should run without Human Intervention
        • Should NOT Crash
        • Robust & Fault Tolerant
        • Exception Handling without Malfunction or unpredictable behaviour
    • Embedded Systems
      • Overview of Embedded Systems
      • Embedded System Design
      • Embedded System Designer
      • More Knowledge
    • Embedded System Designer
      • Specialist
      • Knowledge of Theory & Practical Techniques of both Hardware & Software
      • Strong Foundation in
        • Digital Logic Ckts, ADCs, DACs, PLCs, FPGAs
        • Microcontrollers & Interfacing Techniques
        • Assembly Language Programming
        • High Level Language Programming [C/C++]
        • Writing ISRs
        • RTOS
    • Job Oppurtunities
      • Employers
        • Manufacturers of
          • Telecom Products
          • Automatons & Industrial Robots
          • Automated Production & Diagnostic Eqpt
        • Software Development Firms
      • Remuneration
        • Lucrative
    • Embedded Systems
      • Overview of Embedded Systems
      • Embedded System Design
      • Embedded System Designer
      • More Knowledge
    • For More Knowledge
      • Books
      • Hands-on Training
    • Books on Embedded Systems
      • An Embedded System Primer
        • David E Simon
      • Embedded System Design
        • Steve Heath
      • The Art of Programming Embedded Systems
        • Jack G Ganssle
      • Fundamentals of Embedded Software - Where C and Assembly Meet
        • Daniel W Lewis
      • Real Time Systems & Programming Languages
        • Alan Burns & Andy Wellings
      • Real Time Programming
        • Moore Grehan
    • Training on Embedded Systems
      • TCIL, & their Branches & Franchisees
        • Telecom Consultants India Ltd
        • formed by DoT
      • ECIL, Hyderabad
        • Electronic Corporation of India Ltd
      • Beware !
      • Many institutes boast of embedded system training
        • teach only soldering & assembling using kits
        • do not teach theory or design
    • Thank You !