Embedded Systems

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Embedded Systems

• By Sushant Kumar

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Structure of the seminar

• Introduction
• History of embedded systems
• Characteristics
• Embedded systems for meters

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Introduction

• Part 1

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

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

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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

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

• Signal processing systems
• Real-time video, DVD players, Medical equipment.
• Distributed control
• Network routers, switches, firewalls,
• Small systems
• Mobile phones, home appliances, toys, smartcards,
  MP3 players, PDAs, digital cameras, sensors, pc
  keyboard mouse
• Modern cars Up to 100 or more processors
• Engine control unit
• ABS systems (Anti Lock Brake systems)
• Emissions control
• Diagnostics and Security systems
• Accessories (doors, windows etc)

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History of Embedded Systems

• Part 2

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

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

• Part 2

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Characteristics of Embedded Systems

1. Interface
2. Complexity
3. Platform
4. Peripherals
5. Tools
6. Reliability
7. Volume

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1. Interface
Interface
No User Interface
Full User Interface
Performing user- defined PDAs
Dedicated to one Task Missile guidance system
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2. Complexity
Complexity
Simple systems
Complex systems

• Connected to a network
• Touch screen
• Real time constraints
• Part of a critical operation

• Use buttons,small character/ digit-only displays
• simple menu system

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3. CPU Platform

• Many different CPU architectures used in embedded
  designs such as ARM, MIPS, x86, PIC, 8051 etc
• Desktop computer market is limited to just a few
  architectures

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CPU Platform

• PC/104 is a typical base for small, low-volume
  embedded system design.
• Uses an embedded real-time operating system such
  as MicroC/OS-II, QNX or VxWorks

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CPU Platform

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

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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)

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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

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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

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

• Part 4

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Electric power consumption

• 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

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Limitations of the meter

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

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Demand Curve
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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

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Ideal power curve
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When current and voltage are not in-phase
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Power factor penalty

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

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Multi function meter

• Extend for smaller commercial customer
• Even for residences
• Contract can be varied

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Billing

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

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Design Fundamentals

• Means of taking samples
• Display
• Communication subsystem
• Non-volatile memory
• Power supply
• Stored program micro-controller

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Hardware design
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Choosing a micro-controller

• Feature set
• Code space
• Data Space
• Data converter
• Real-time clock

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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.

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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

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For detailed report

• www.sushantkumar.wordpress.com/tech

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Thank You ?