embedded sysytems

8/9/2019 Embedded Sysytems

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INTRODUCTION TOEMBEDDED

SYSTEMS

EMBEDDED SYSTEMDESIGN

(ECE 1021)

PRIYANKA MATHUR

Asst. Professor/ECE


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PURPOSE OF EMBEDDED SYSTEM

Each Embedded S ystems is designed t o serve thepurpose of any on e or a combination of thefollowing t asks.

Data Collection/Storage/RepresentationData CommunicationData (Signal) Processing

MonitoringControl Application Specic User In


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DATA COMMUNICATION

From complex satellite communicationsystems to simple home networkingsystems

The data communication can happenthrough a wired interface (likeEthernet, RS-232C/USB/IEEE1394 etc)or wireless interface (like Wi-Fi,GSM,/GPRS, Bluetooth, etc)

Network hubs, Routers, switches,Modems etc are typical examples fordedicated data transmission embeddedsystems


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o Speech coding, synthesis, audio video codec,transmission applications etc

o Computational intensive s ystems

o Employs D igital Signal Processors (DSPs)

DATA (SIGNAL) PROCESSING

Digital hearing Aid em ploying S ignal Processing Technique


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MONITORING

They are used for determining the state of somevariables u sing i nput sensors

They can not impose c ontrol over va riables.

Electro Cardiogram (ECG) machine for monitoringthe h eart beat of a patient

The sensors used i n ECG are the different Electrodesconnected to t he p atient’s b ody

Measuring instruments like Digital CRO, DigitalMulti meter, Logic Analyzer etc used in Control &Instrumentation applications are a lso exa mples ofembedded sys tems for monitoring purpose


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CONTROLUsed for imposing control over some variables

according to t he ch anges i n input variables

Embedded system with control functionalitycontains bot h sensors an d actuators

Sensors are connected to the input port forcapturing the changes i n environmental variableor measuring variable

The actuators connected to the output port are

controlled according to the changes in inputvariable to put an impact on the controllingvariable to bring the con trolled variable to thespecied range

Eg:Air conditioner for controlling roomtemperature


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APPLICATION SPECIFIC USERINTERFACE

Contains Application Specic Userinterface (rather t han general standardUI ) like k ey board, Display units et c

Aimed at a specic

Mobile handsets, Control units inindustrial applications et c are exa mplesfor th is


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TYPICAL EMBEDDEDSYSTEM


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TYPICAL EMBEDDED SYSTEM


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TYPICAL EMBEDDED SYSTEM


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General Purpose Processor (GPP) Vs Application

Specic Instruction Set Processor (ASIP)

General Purpose Processor or GPP is a processor designed for generalcomputational tasks

GPPs are pro duced in large vol umes and targeting the gen eral market.

Due t o the h igh volume production, the per u nit cost for a ch ip is lowcompared t o ASIC or other specic ICs

A typical general Unit (ALU) and Control Unit (CU)

Application Specic with architecture and instruction set optimized to specicdomain/application requirements like Network processing, Automotive,Telecom, media applications, digital signal processi ng, controlapplications etc.

THE TYPICAL EMBEDDED SYSTEM


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need for an ASIP arises when the traditionalgeneral purpose processor are u nable t o meet theincreasing application needsSome Microcontrollers (like Automotive AVR,USB AVR from Atmel), System on Chips, DigitalSignal Processors et c are exa mples of ApplicationSpecic Instruction Set Processors (ASIPs)

ASIPs incorporate a processor and on-chipperipherals, demanded by the applicationrequirement, program and data m emory


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THE CORE OF THE EMBEDDEDSYSTEMS

The core of the em bedded system falls i nto a ny one ofthe following ca tegories.

General Purpose and Domain SpecicProcessors

MicroprocessorsMicrocontrollers

Digital Signal ProcessorsProgrammable Logic Devices (PLDs )

Application Specic Integrated Circui )Commercial off the shelf Components (COTS)


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PROCESSOR

A Processor is the heart of theEmbedded System.

For an embedded system designerknowledge of microprocessor andmicrocontroller i s a must.

Two Essential Units: Operatio nsControl Unit (CU), FetchExecution Unit (EU) Execute


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VARIOUS PROCESSOR1. General Purpose processor (GPP)

MicroprocessorMicrocontrollerEmbedded ProcessorDigital signal Processor

2. Application Specic System Processor (ASSP)

3. Multi Processor System using GPPs


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MICROPROCESSOR A microprocessor is a single chip semi

conductor device also which is a computeron chip, but not a complete computer.

Its CPU contains an ALU, a programcounter, a stack pointer, some workingregister, a clock timing circuit andinterrupt circuit on a single chip.

To make complete micro computer, onemust add memory usually ROM and RAM,memory decoder, an oscillator and anumber of serial and parallel ports.


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HISTORY OF MICROPROCESSOR

1st Generation (4 b it processors)4004 and 4040 4 bit in early 1970 by Intel (Integrated Electronics)

2nd Generation (8 b it processors)8008 and 8080 8 bit in 1974 Intel with +5 V Input supply 8080 8085 8bit

3rd Generation (16 bit processors)8086 16 b it. Same a s 8086, the 8088 introduced 8088 has only 8 bit databus(This made it easier to interface to the common 8 bit peripheraldevices av ailable a t the t ime)

Followed by:The 80186 & 80286 (16 bit processor), the 80386 & 80486 (a 32 bitprocessor), leading to the Pentium range of microprocessors (64 bitprocessors) available today. The 80x86 and Pentium processors haveall been designed for use in personal computer type applications and

have large memory maps.


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VARIOUSMICROPROCESSORS

Intel4004, 40408080, 80858086, 8088,80186, 80188

80286, 80386x86-64

Motorola

6800

680968000G3, G4, G5

Zilog

Z80, Z180, eZ80Z8, eZ8

and others


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MICROCONTROLLER

A microcontroller is a functional computersystem-on-a-chip. It contains a processor ,memory, and programmable input/outputperipherals.

Microcontrollers include an integrated CPU,memory (a small amount of RAM, programmemory, or both) and peripherals capable ofinput and output.


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VARIOUSMICROCONTROLLERS

INTEL8031,8032,8051,8052,8751,8752

PIC8-bit PIC16, PIC18,

16-bit DSPIC33 / PIC24,PIC16C7x

MotorolaMC68HC11


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MICROPROCESSOR VS MICROCONTROLLER

MICROPROCESSOR MICROCONTROLLER

The functional blocks are ALU,registers, timing & control units

It includes functional blocks ofmicroprocessors & in additionhas timer, parallel i/o, RAM,

E R!M, A"# & "A#$it handling instruction is less,!ne or t%o t pe onl

Man t pe of bit handlinginstruction

Rapid mo'ements of code anddata bet%een e(ternal memor &M

Rapid mo'ements of code and

data %ithin M#

It is used for designing generalpurpose digital computers s stem

The are used for designingapplication specific dedicateds stems


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Microprocessor MicrocontrollerA silicon chip representing a CentralProcessing Unit (CPU), which is capable of

performing arithmetic as well as logicaloperations according to a pre-defined set ofInstructions

A microcontroller is a highly integrated chip thatcontains a CPU, scratch pad RA , !pecial and"eneral purpose Register Arrays, #n ChipR# $%&A!' memory for program storage, imerand Interrupt control units and dedicated I$# ports

It is a dependent unit It re*uires thecombination of other chips li+e imers,Program and data memory chips, Interruptcontrollers etc for functioning

It is a self contained unit and it doesn t re*uiree ternal Interrupt Controller, imer, UAR etc for itsfunctioning

ost of the time general purpose in designand operation

ostly application oriented or domain specific

.oesn t contain a built in I$# port he I$#

Port functionality needs to be implementedwith the help of e ternal ProgrammablePeripheral Interface Chips li+e /011

ost of the processors contain multiple built-in I$#

ports which can be operated as a single / or 23 or 40 bit Port or as indi5idual port pins

argeted for high end mar+et where performance is important

argeted for embedded mar+et where performance isnot so critical (At present this demarcation is in5alid)

&imited power sa5ing options compared tomicrocontrollers

Includes lot of power sa5ing features

Microprocessor VsMicrocontroller


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EMBEDDED PROCESSOR

Special microprocessors & microcontrollersoften called, Embedded processors.

An embedded processor is used when fastprocessing fast context-switching & atomic

ALU operations are needed.

Examples : ARM 7, INTEL i960, AMD 29050.


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DIGITAL SIGNAL PROCESSOR

DSP as a G PP is a s ingle chip VLSI unit.

It includes t he com putational capabilities of microprocessor and multiply& accumulate units (MAC).

DSP has l arge n umber of applications such as i mage processing, audio,

video & telecommunication processing sys tems.

It is u sed when signal processing functions are t o be p rocessed fast.

DSPs implement algorithms in hardware which speeds up the executionwhereas general purpose processors implement the algorithm in

rmware an d the speed of execution depends pri marily on the clock forthe p rocessors

Examples : TMS320Cxx, SHARC, Motorola 5600xx


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RISC/CISCRISC CISC

Lesser no. of instruct Greater no. of Instructions

Instruction Pipelining and increasedexecution speed

Generally no i nstruction pipelining feature

Orthogonal Instruction Set (Allowseach instruction to operate on anyregister and use any addressing m ode)

Non Orthogonal Instruction Set (Allinstructions are n ot allowed to op erate on anyregister an d use a ny addressing mode. It is

instruction specic)Operations are perf ormed on registersonly, the only memory operations areload and store

Operations are performed on registers ormemory depending on the instruction

Large number of registers areavailable

Limited no. of general purpose regi sters

Programmer needs to write more codeto ex ecute a task since t he i nstructionsare si mpler ones

Instructions are l ike m acros in C language. Aprogrammer can achieve the desiredfunctionality with a single instruction whichin turn provides the effect of using moresimpler si ngle i nstructions i n RISC

Single, Fixed length Instructions Variable length InstructionsLess Silicon usae and in count More silicon usae since more additional


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Harvard V/s Von-Neumann Processor/Controller Architecture

The terms Harvard and Von-Neumann refers to the processor architecturedesign.

Microprocess ors/controllers based on the Von-Neumann architecture s haresa single common bus for fetching both instructions and data. Programinstructions an d data ar e stored in a common m ain memory

Microprocess ors/controllers based on the Harvard architecture w ill haveseparate data bus an d instruction bus. This allows the data transfer an dprogram fetching t o occur simultaneously on both buses

With Harvard architecture, the da ta m emory can be read and written whilethe program memory is being accessed. These separated data memory and

code memory buses allow one instruction to execute while the nextinstruction is f etched (“Pre-fetching”)

Von-Neumann ArchitectureHarvard Architecture


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Harvard Architecture Von-Neumann Architecture!eparate buses for Instruction and.ata fetching

!ingle shared bus for Instruction and .atafetching

6asier to Pipeline, so high performance can be achie5ed

&ow performance Compared to 'ar5ardArchitecture

Comparati5ely high cost Cheaper 7o memory alignment problems Allows self modifying codes 8

!ince data memory and programmemory are stored physically indifferent locations, no chances foraccidental corruption of programmemory

!ince data memory and program memoryare stored physically in same chip,chances for accidental corruption of

program memory

Harvard V/s Von-Neumann Processor/Controller Architecture


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Big-endian V/s Little-endian processors

Endianness species t he or der in which the d ata is s tored in thememory by processor operations i n a multi byte sys tem (Processorswhose w ord size i s gr eater than one by te). Suppose t he w ord lengthis two byt e t hen data can be s tored i n memory in two different ways

Higher order of data b yte at the h igher memory a nd lower order of databyte a t location just below the h igher memoryLower order of data by te at the h igher memory and h igher order of databyte a t location just below the h igher memory

Little-endian m eans t he l ower-order by te of the d ata is s tored inmemory at the l owest address, and the h igher-order byte a t thehighest address. (The l ittle en d comes rst)

Big-endian m eans t he h igher-order byte of the d ata is s tored inmemory at the l owest address, and the l ower-order byte a t thehighest address. (The b ig end comes rst.)



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Big-endian V/s Little-endian processors


Little-endian Operation

Big-endian Operation


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APPLICATION SPECIFICSYSTEM PROCESSOR (ASSP)

ASSP is dedicated to specic tasks andprovides a faster solution.

An ASSP is used as an additionalprocessing unit for r unning the a pplicationin place of using embedded software.

Examples : IIM7100, W3100A


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APPLICATION SPECIFIC INTEGRATEDCIRCUIT (ASIC)

o A microchip designed to perf unique application. It is used as replacement toconventional general purpose l ogic chips.

o ASIC integrates severa chip and thereby r educes the system developmentcost

o ASICs can be pre-fabricated for a special

application or it can be custom fabricated byusing the components from a re-usable ‘ buildingblock ’ library of components for a particularcustomer application


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COMMERCIAL OFF THE SHELF COMPONENT(COTS)

Commercial off the Shelf Component (COTS)

o A Commercial off-the-shelf (COTS) product is onewhich is used ‘ as-is ’

o

COTS products are designed in such a way to provideeasy integration and interoperability with existingsystem components

o Typical examples for the COTS hardware unit areRemote Controlled Toy Car control unit including theRF Circuitry part, High performance, high frequencymicrowave electronics (2 to 200 GHz), High bandwidthanalog-to-digital converters, Devices and componentsfor op eration at very h igh temperatures, Electro-opticIR imaging arrays, UV/IR Detectors e tc


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Programmable Logic Devices (PLDs) – CPLDsand FPGA

o Field Programmable Gate Arrays (FPGAs) and ComplexProgrammable Logic Devices (CPLDs) are the two majortypes of programmable l ogic devices

o FPGAs offer the highest amount of logic density, themost features, and the h ighest performance.

o These ad vanced FPGA devices also offer features such asbuilt-in hardwired processors (such as the IBM PowerPC), substantial amounts of memory, clock management

systems, and support for m any of the latest, very fastdevice-to-device si gnaling technologies

PROGRAMMABLELOGIC


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PROGRAMMABLE LOGICDEVICES (PLDS) – CPLDS ANDFPGAo FPGAs are used in a wide variety of applications

ranging from data processing and storage, toinstrumentation, telecommunications, and digitalsignal processi ng

o

CPLDs, by contrast, offer much smaller amounts oflogic - up to a bout 10,000 gates

o CPLDs offer very p redictable timing characteristicsand are t herefore i deal for c ritical control applications

o CPLDs such as the Xilinx CoolRunner series a lsorequire extremely low amounts of power and are veryinexpensive, making them ideal for cost-sensitive,battery-operated, portable a pplications such as mobilephones an d digital handheld assistants

embedded sysytems

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