39245196 intro-es-iii
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Transcript of 39245196 intro-es-iii
Classification of Embedded Systems
Three Types of Embedded Systems are :
(1) Small Scale (2) Medium Scale(3) Sophisticated
Small Scale Embedded Systems
Designed with a single 8 or 16 bit µC. Little Hardware & Software
complexities. Involves Board level design. May be Battery Operated. Programming Tools Needed:
Editor, Assembler, Cross Assembler specific to µC or µP used.
Medium Scale Embedded Systems
Designed with Single or a few 16-32 Bit µC 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*
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 their Hardware
Certain S/W functions implemented in H/W* to obtain additional speed by saving execution time.
Development Tools for such systems may not be readily available at a reasonable cost or may not be available at all
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
1998-19991999-2000
Selection of a Processor
Instruction Set, Pipelining, Super Scalar Execution.
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]
Types of Processors 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)
Microprocessor (µP):
Single VLSI Chip having CPU and (may have) Cache memory, Floating point Arithmetic Coprocessor, Pipelining Architecture to process instructions faster.
CPU Instruction Set supports ALU operations, Data Transfer and Stack operations, Input and Output, Program Control, Sequencing and Supervisory operations
Software located in external memory Chips
Examples- Microprocessors
Intel 8085Intel 8086/ 88
8 Bit 16 bit
Simple control Applications
Intel 80386Intel 80486
32 bit Graphics Accelerator, Network Interface card
Pentium 64 bit Encryption Engine with 0.464 Gbps data rate
PowerPC MPC 823
32 Bit Floating Pt Coprocessor, USB, IrDA,
Microcontrollers
Contains ROM, RAM Memories on Chip Enhanced Input Output capabilities Limited Computational Abilities More Functional Units on Chip:
Timers, Watchdog Timer, Interrupt Controller, UART, Parallel I/O Ports, A/D Converter and PWM Circuit for D/A converters
Functional Circuits in a Chip or Core of Microcontroller
Processor ROM/ EPROM I/O Ports Controls and Interfaces
Data and
Stack RAM
Timers
External MemoryInterface
Serial UART
A/D Converter
Interrupt Controller
PWM for D/A
WatchdogTimer
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 with RISC
Embedded Processor
Specially designed µC / µP 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 Aerodynamics Applications
Examples- Embedded Processors
ARM 7 and ARM 9
Image Processing
Intel i960 4 Channel DMA Controller
Digital Signal Processor
Computational capabilities of a µP Has Multiply – Accumulate (MAC) Units Very Large Instruction Word Processes Single Instruction Multiple
Data(SIMD) Fast processing of Discrete Cosine
Transforms and Inverse (IDCT) algorithms in Image Processing, Multimedia, Audio, Video, HDTV, DSP Modems and Telecom Processing Systems
Examples - DSP
TMS 320C6211 Texas Instruments
SHARC Analog Devices
5600xx Motorola
Application Specific System Processor (ASSP)
Dedicated to perform specific tasks in H/W Like
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
Compression & Decompression Application
in MPEG2 or MPEG4 Standards Compression of Video signal is done before
storing or transmitting. Decompression is done before retrieving or receiving these signals
If embedded Software is run on GPP, separate DSP(s) are required to achieve real time processing. A single dedicated ASSP processor provides a faster solution.
Encryption & Decryption Applications
When 2 Systems needs data communications on a common bus and protocol, Embedded Software (with some RTOS feature) may take longer time than a hardware based approach
ASSP Processor (W3100) from i2Chip has, for example TCP, UDP, IP, ARP, Ethernet 10/100 Media Access Control (MAC)
Provides RTOS less, Internet Connectivity in H/W 5 times faster than a GPP based software solution
Serial to Ethernet Converter Application
IIM 7100 processes data in Real Time by hardware protocol stack
Requires no change in Application Firmware
Provides economical and smallest RTOS solution.
Multiple Processor System using GPP Multiple GPP are used in Mobile
Phone. 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 and
displays
Multiple Processors in Video Conferencing
Image Pixels are just 144 x 176 as against 525 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 before transmission
A single DSP does not suffice. Multiple DSP(s) are needed to process images during Video Conferencing in real time.
Application Specific Instruction Processor-ASIP
For many Applications, the GPP cores may not suffice. For examples: Security Applications, Smart Cards, Video games, Palmtop computers, Cell phones, Mobile Internet, Satellite Missile Systems Gbps Transceivers and Gbps LAN
systems
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, µP or µC) might be needed on a chip.
Examples: (1) Cell phone (2) ASIP for HDTV to process an image with 1920 x 1020 pixels on TV screen.