Embedded Systems

Structure of the seminarIntroduction

History of embedded systems

Characteristics

Embedded systems for meters

IntroductionPart 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 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

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 controller

Micro controllers have built in peripherals and memorywhich reduces the size of the system

Application AreasSignal 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)

History of Embedded Systems

Part 2

Apollo Guidance computer

The Apollo Guidance Computer, the first recognizablemodern 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 logicReduced prices on nand gate ICs from $1000/each to $3/eachMedicinal appliancesAvionics, such as inertial guidance systems, flight control systemsCellular telephones and telephone switchesHome automation products

Other developmentsFirst MicroprocessorIntel 4004Required external memory and support chips

By mid 1980’s 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

Moore’s law

Characteristics of Embedded Systems

Part 2

Characteristics of Embedded Systems

1. Interface2. Complexity3. Platform4. Peripherals5. Tools6. Reliability7. Volume

1. InterfaceInterface

No User Interface

Full User Interface

Performing user- defined

PDA’s

Dedicated to oneTaskMissile guidancesystem

2. ComplexityComplexity

Simple systems Complex systems

•Use buttons,small character/ digit-only displays

•simple menu system

•Connected to a network

•Touch screen

•Real time constraints

•Part of a critical operation

3. CPU PlatformMany 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

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

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.

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

5. ToolsEmbedded 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 issuesSystem cannot be shut down for repair

Solutions involve subsystems with spares

system must be kept running for safety and monetary reasons

7. VolumeVolume

High Volume Low Volume

Minimizing cost is usually the primary design consideration

Used when cost is not a major factor

Performance and reliability constraints

Embedded systems for Meters

Part 4

Electric power consumption

Electric power consumption is not constant whole dayPeak period is between 1 pm and 4 pmSystem must be engineered to meet peak power

Limitations of the meterMechanical deviceProne to wear,shockMaintains no record of timeOnly Counts the number of rotations of the wheel

Demand Curve

Real power limitationIdeally current and voltage are in phaseEvery volt-ampere delivered becomes a watt of power usedInduction motors and lamp ballasts cause current to flow out of phaseFewer actual watts are used than delivered

Ideal power curve

When current and voltage are not in-phase

Power factor penaltyIndustrial customers must by contract maintain power factorPower factor=Ratio of real power used to volt amperes deliveredPay penalty if above some agreed upon values

Multi function meterExtend for smaller commercial customer

Even for residences

Contract can be varied

BillingNetworked system can facilitate automationNo need to send personnelBetter accuracy and lesser burden

Design Fundamentals1. Means of taking samples2. Display3. Communication subsystem4. Non-volatile memory5. Power supply6. Stored program micro-controller

Hardware design

Choosing a micro-controller

Feature setCode spaceData SpaceData converterReal-time clock

ConclusionA quiet revolution is in progress in the utility industry.Static metering devices, have been in use for the better part of a centuryGradually being replaced with multi-rate, multifunction metersCapable of more accurately accounting for utility usage.

Referenceswww.maxim-ic.comwww.electronicsforu.comwww.refdesign.techonline.comwww.wikipedia.orgwww.powerelectronics.comwww.ucpros.comwww.pdfserv.maxim-ic.com

For detailed report

www.sushantkumar.wordpress.com/tech

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