Embedded Systems By Sushant Kumar Structure of the

Embedded Systems By Sushant Kumar

Structure of the seminar Introduction History of embedded systems Characteristics Embedded systems for meters

Introduction Part 1

What is an Embedded System ? An embedded system is a special -purpose computer system designed to perform a dedicated function

An Embedded system A generic embedded system

Why Embedded system ? Performance n Technology Advances w CMOS VLSI dominates older technologies (TTL, ECL) n Computer architecture improvements w RISC, superscalar, RAID, … Price n Simpler development w CMOS VLSI: smaller systems, fewer components n Higher volumes w CMOS VLSI : same device cost 10, 000 vs. 10, 000 units

Embedded system vs General Computer Performs one or a few pre-defined tasks Very specific requirements Task-specific hardware and mechanical parts Often mass-produced Design engineers can optimize it

Embedded System Microprocessor Micro controllers have built in peripherals and memory which reduces the size of the system

Application Areas Signal processing systems n Real-time video, DVD players, Medical equipment. Distributed control n Network routers, switches, firewalls, “Small” systems n Mobile phones, home appliances, toys, smartcards, MP 3 players, PDAs, digital cameras, sensors, pc keyboard & mouse Modern cars: Up to 100 or more processors n n n Engine control unit ABS systems (Anti Lock Brake systems) Emissions control Diagnostics and Security systems Accessories (doors, windows etc)

History of Embedded Systems Part 2

Apollo Guidance computer The Apollo Guidance Computer, the first recognizable modern embedded system developed by Charles Stark Draper at the MIT Instrumentation Laboratory

Minuteman Missile 1966 First mass-produced embedded system Autonetics D-17 guidance computer Built from transistor logic Reduced prices on nand gate ICs from $1000/each to $3/each Medicinal appliances Avionics, such as inertial guidance systems, flight control systems Cellular telephones and telephone switches Home automation products

Other developments First Microprocessor Intel 4004 Required external memory and support chips cost of a microcontroller fell below $1 By mid 1980’s micro controllers came into existence By the end of the 80 s, embedded systems were the norm rather than the exception

Moore’s law

Characteristics of Embedded Systems Part 2

Characteristics of Embedded Systems 1. 2. 3. 4. 5. 6. 7. Interface Complexity Platform Peripherals Tools Reliability Volume

1. Interface No User Interface Full User Interface Dedicated to one Task Performing userdefined Missile guidance system PDA’s

2. Complexity Simple systems Complex systems • Use buttons, small character/ digit-only displays • Connected to a network • simple menu system • Real time constraints • Touch screen • Part of a critical operation

3. CPU Platform Many different CPU architectures used in embedded designs such as ARM, MIPS, x 86, PIC, 8051 etc… Desktop computer market is limited to just a few architectures

CPU Platform… PC/104 is a typical base for small, lowvolume embedded system design. Uses an embedded real-time operating system such as Micro. C/OS-II, QNX or Vx. Works

CPU Platform… Very-high-volume embedded systems use the system on a chip (So. C), an application-specific integrated circuit (ASIC) CPU core was purchased and added as part of the chip design.

4. Peripherals Serial Communication Interfaces Universal Serial Bus (USB) Networks: Ethernet, Controller Area Network Timers: PLL(s), Capture/Compare and Time Processing Units General Purpose Input/Output (GPIO) Analog to Digital/Digital to Analog (ADC/DAC)

5. Tools Embedded system designers use compilers, assemblers, and debuggers Utilities to add a checksum or CRC to a program Emulator replaces the microprocessor with a simulated equivalent

6. Reliability issues System cannot be shut down for repair Solutions involve subsystems with spares system must be kept running for safety and monetary reasons

7. Volume High Volume Minimizing cost is usually the primary design consideration Low Volume Used when cost is not a major factor Performance and reliability constraints

Embedded systems for Meters Part 4

Electric power consumption is not constant whole day Peak period is between 1 pm and 4 pm System must be engineered to meet peak power

Limitations of the meter Mechanical device Prone to wear, shock Maintains no record of time Only Counts the number of rotations of the wheel

Demand Curve

Real power limitation Ideally current and voltage are in phase Every volt-ampere delivered becomes a watt of power used Induction motors and lamp ballasts cause current to flow out of phase Fewer actual watts are used than delivered

Ideal power curve

When current and voltage are not inphase

Power factor penalty Industrial customers must by contract maintain power factor Power factor=Ratio of real power used to volt amperes delivered Pay penalty if above some agreed upon values

Multi function meter Extend for smaller commercial customer Even for residences Contract can be varied

Billing Networked system can facilitate automation No need to send personnel Better accuracy and lesser burden

Design Fundamentals 1. 2. 3. 4. 5. 6. Means of taking samples Display Communication subsystem Non-volatile memory Power supply Stored program micro-controller

Hardware design

Choosing a micro-controller Feature set Code space Data Space Data converter Real-time clock

Conclusion A quiet revolution is in progress in the utility industry. Static metering devices, have been in use for the better part of a century Gradually being replaced with multi-rate, multifunction meters Capable of more accurately accounting for utility usage.

References www. maxim-ic. com www. electronicsforu. com www. refdesign. techonline. com www. wikipedia. org www. powerelectronics. com www. ucpros. com www. pdfserv. maxim-ic. com

For detailed report www. sushantkumar. wordpress. com/tech

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