Intro Es III

8/8/2019 Intro Es III

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Classification of Embedded Systems

Three Types of Embedded Systems are :

(1) Small Scale

(2) Medium Scale

(3) Sophisticated


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Small Scale Embedded Systems Designed with a single 8 or 16 bit C.

Little Hardware & Software

complexities. Involves Board level design.

May be Battery Operated.

Programming Tools Needed:Editor, Assembler, Cross Assemblerspecific to C or P used.


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Medium Scale Embedded Systems

Designed with Single or a few 16-32

Bit C or DSP or RISC Computer,

Hardware & Software Complexities

Programming Tools: RTOS, Source

Code Engg. Tools, Simulator,

Debugger, IDE.

May employ readily available ASSP

and IP for various functions*


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Sophisticated Embedded Systems Have enormous H/W and S/W complexities, may need

scalable or configurable processors and PLA

Used for cutting edge application that needs H/W &S/W Co-design and integration in final system

Constrained by processing speed available in theirHardware

Certain S/W functions implemented in H/W* to obtainadditional speed by saving execution time.

Development Tools for such systems may not be

readily available at a reasonable cost or may not beavailable at all


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Processor Types Used in New

Embedded Designs

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

4-bit 8-bit 16-bit 32-bit 64-bit Special

1998-1999

1999-2000


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Selection of a Processor

Instruction Set, Pipelining, Super ScalarExecution.

Data Bus Width (8-16-32 Bits) for Arithmetic.

Floating Point Coprocessor, Cache Memory

On-chip peripheral devices, Clock Frequency,

Availability of Retarget-able Compiler and

Hardware Software Co-design Tools Power Saving Modes available

Cost [Components, Development tools, NRE]


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Types ofProcessors used in Emb.

Systems General Purpose Processor (GPP):

Microprocessor

Micro-controller

Digital Signal Processor

Embedded Processor

Application Specific System Processor(ASSP)

Multiprocessor Systems using GPP

Application Specific Instruction Processor(ASIP)


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Microprocessor (P):

Single VLSI Chip having CPU and (may have)Cache memory, Floating point ArithmeticCoprocessor, Pipelining Architecture toprocess instructions faster.

CPU Instruction Set supports ALU operations,Data Transfer and Stack operations, Inputand Output, Program Control, Sequencingand Supervisory operations

Software located in external memory Chips


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Examples- Microprocessors

Intel 8085

Intel 8086/ 88

8 Bit

16 bit

Simple controlApplications

Intel 80386

Intel 80486

32 bit Graphics Accelerator,

Network Interfacecard

Pentium 64 bit Encryption Enginewith 0.464 Gbps data

rate

PowerPC

MPC 823

32 Bit Floating PtCoprocessor, USB,IrDA,


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Microcontrollers Contains ROM, RAM Memories on

Chip

Enhanced Input Output capabilities Limited Computational Abilities

More Functional Units on Chip:

Timers, Watchdog Timer, InterruptController, UART, Parallel I/O Ports,A/D Converter and

PWM Circuit for D/A converters


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Functional Circuits in a Chip or Core ofMicrocontroller

Processor ROM/ EPROMI/O Ports

Controls and

Interfaces

Data

andStack

RAM

Timers

External Memory

Interface

Serial UART

A/D Converter

Interrupt

Controller

PWM for D/A

Watchdog

Timer


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Microcontroller Examples

68HC11,HC12

Motorola CISC

8051, 80251 Intel CISC

80186,80386

Intel CISC

PIC 16F84,

PIC 16F876

Microchip CISC

Enhancement of ARM7,ARM9

TI CISC withRISC


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Embedded ProcessorSpecially designed C / P with:

(1) Fast Context Switching and thus lower latencies

of the task in complex real time applications(2) Atomic ALU Operations and thus no shared data

problem

(3) RISC Core for fast, more precise and intensive

calculations by embedded software Needed in Real time Image

processing and AerodynamicsApplications


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Examples- Embedded ProcessorsARM 7 and

ARM 9

Image Processing

Intel i960 4 Channel DMAController


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Digital Signal Processor Computational capabilities of a P

Has Multiply Accumulate (MAC) Units

Very Large Instruction Word

Processes Single Instruction MultipleData(SIMD)

Fast processing ofDiscrete CosineTransforms and Inverse (IDCT) algorithms

in Image Processing, Multimedia, Audio,Video, HDTV, DSP Modems and TelecomProcessing Systems


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Examples - DSPTMS 320C6211 Texas Instruments

SHARC Analog Devices

5600xx Motorola


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Application Specific System

Processor (ASSP)

Dedicated to perform specific tasks in H/WLike

Provides Faster Solution using a single Chip

Configured & Interfaced with the rest of ES.

Target Application Examples:

Video Compression &Decompression (MPEG)

Encryption and Decryption Implementations

Serial to Ethernet Converter Application


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Compression & Decompression

Application

in MPEG2 or MPEG4 Standards

Compression of Video signal is done beforestoring or transmitting. Decompression isdone before retrieving or receiving thesesignals

If embedded Software is run on GPP,separate DSP(s) are required to achievereal time processing. A single dedicatedASSP processor provides a faster solution.


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Serial to Ethernet ConverterA

pplication IIM 7100 processes data in Real Time

by hardware protocol stack

Requires no change in ApplicationFirmware

Provides economical and smallestRTOS solution.


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Multiple Processor System using GPP

Multiple GPP are used in MobilePhone. Tasks performed are:

Speech signal compression and coding

Dialing Modulating & transmitting

Demodulating and Receiving

Signal decoding and Decompression

interface to LCD display and Keypad

SMS protocol based messaging anddisplays


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Multiple Processors in Video

Conferencing Image Pixels are just 144 x 176 as against525 x 625 pixel in video picture on TV.

30 Samples of Images have to be taken in a

second 144 x 176 x 30 = 760320 Pixels per second

are to be processed by Compression beforetransmission

A single DSP does not suffice. Multiple DSP(s)are needed to process images during VideoConferencing in real time.


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Application Specific Instruction

Processor-A

SIP For many Applications, the GPP cores

may not suffice. For examples:

Security Applications, Smart Cards,

Video games, Palmtopcomputers,

Cell phones, Mobile

Internet, Satellite Missile Systems

Gbps Transceivers and Gbps LANsystems


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Application Specific Instruction

Processor-ASIP

Special Processing Units needed in a VLSI

designed Circuit to function as a Processor,called Application Specific Instruction

Processors (ASIP) Both the Configurable processor (FPGA cum

ASIP) and Non-configurable processors (DSP,P or C) might be needed on a chip.

Examples: (1) Cell phone

(2) ASIP for HDTV to process an image with1920 x 1020 pixels on TV screen.

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