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General Purpose vs. Application Specific Processors Slide 1Eduard Turcan October 24, 2001

Processors and Architecturesfor Embedded Systems

General Purposevs.

Application Specific Processors

General Purpose vs. Application Specific Processors Slide 2Eduard Turcan October 24, 2001

Lectures 5 & 6 Overview

• General Purpose vs. Application SpecificProcessors

• Core (IP)-based design

• Reconfigurable Systems

General Purpose vs. Application Specific Processors Slide 3Eduard Turcan October 24, 2001

Agenda

• Trends in Embedded-Microprocessor design

• Embedded System Architectures

• Customized Instruction Sets for EmbeddedProcessors

• Selected Co-design problems

• Conclusions

General Purpose vs. Application Specific Processors Slide 4Eduard Turcan October 24, 2001

Embedded Microprocessors Overview

• Desktop vs. Embedded processors

• Microcontrollers and Microprocessors

• New applications drive requirements– game consoles

– handheld, palmtop, automobile and network PCs

– cellular phones and other mobile communicators

– modems, fax machines, printers, etc.

– digital cameras

Trends in EmbeddedMicroprocessor design

General Purpose vs. Application Specific Processors Slide 5Eduard Turcan October 24, 2001

Comparing Embedded Processors

• Power consumption

• Code density

• Peripheral integration and chipsets

• Multimedia acceleration

• Price/performance ratio

Trends in EmbeddedMicroprocessor design

General Purpose vs. Application Specific Processors Slide 6Eduard Turcan October 24, 2001

Standardization

• The heterogenity of embedded architectures

• A need to unify the embedded processor market?

• Windows CE and JAVA as examples

• Will management influence standardization?

Trends in EmbeddedMicroprocessor design

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General Purpose vs. Application Specific Processors Slide 7Eduard Turcan October 24, 2001

Introduction to ES Architectures

• ES Architectures are determined by:– circuit technology;

– application requirements;

– market constraints:• strict cost margins

• time-to-market and predictable design time

• (hard) time constraints

• power dissipation

• safety

• physical constraints

Embedded System ArchitecturesIntroduction

General Purpose vs. Application Specific Processors Slide 8Eduard Turcan October 24, 2001

Components and Systems

• Components as function blocks

• Systems as large entities of integratedcomponents

• Single control thread vs. multiple control threads

• architecture specialization– component specialization techniques

– system specialization techniques

Embedded System ArchitecturesArchitecture Specialization Techniques

General Purpose vs. Application Specific Processors Slide 9Eduard Turcan October 24, 2001

Component Specialization Techniques

• Instruction set specialization

• Function unit and data path specialization

• Memory specialization

• Interconnect specialization

• Control specialization

Embedded System ArchitecturesArchitecture Specialization Techniques

General Purpose vs. Application Specific Processors Slide 10Eduard Turcan October 24, 2001

System Specialization Techniques

• Load distribution– Control decomposition (control clustering)

– Data decomposition (data clustering)

• Component interaction

Embedded System ArchitecturesArchitectures Specialization Techniques

General Purpose vs. Application Specific Processors Slide 11Eduard Turcan October 24, 2001

System Control Specialization

• Asymmetric control relationships require globalcontrol flow

• The following global control mechanisms can bedistinguished:– Independently controlled components

– Dependent coprocessors

– Incrementally controlled coprocessors

– Partially dependent coprocessors

Embedded System ArchitecturesArchitecture Specialization Techniques

General Purpose vs. Application Specific Processors Slide 12Eduard Turcan October 24, 2001

Dependent CoprocessorsEmbedded System Architectures

Architecture Specialization Techniques

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General Purpose vs. Application Specific Processors Slide 13Eduard Turcan October 24, 2001

Incrementally Controlled CoprocessorsEmbedded System Architectures

Architecture Specialization Techniques

General Purpose vs. Application Specific Processors Slide 14Eduard Turcan October 24, 2001

Partially Dependent CoprocessorsEmbedded System Architectures

Architecture Specialization Techniques

General Purpose vs. Application Specific Processors Slide 15Eduard Turcan October 24, 2001

Application System Classes

• Computation oriented systems

• Control dominated systems

• Data dominated systems

• Mixed systems

Embedded System ArchitecturesEmbedded System ArchitecturesTarget Architectures and Application System Classes

General Purpose vs. Application Specific Processors Slide 16Eduard Turcan October 24, 2001

Control Dominated Systems Architectures

• Input MOCs are coupled FSM or Petri-Nets

• Co-design problems:– execution of concurent FSMs/Petri-Nets reacting to

asynchronous input events

– FSM transition synchronization

– event scheduling

– correctness

Embedded System ArchitecturesArchitectures for Control Dominated Systems

General Purpose vs. Application Specific Processors Slide 17Eduard Turcan October 24, 2001

8051 - an 8bit Microcontroller ArchitectureEmbedded System Architectures

Architectures for Control Dominated Systems

General Purpose vs. Application Specific Processors Slide 18Eduard Turcan October 24, 2001

Examples - Philips 80C552Embedded System Architectures

Architectures for Control Dominated Systems

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General Purpose vs. Application Specific Processors Slide 19Eduard Turcan October 24, 2001

Data Dominated Systems Architectures

• Data transport or processing is dominant

• Flow graph languages are used to describe suchsystems

• Opportunities for specialization:– periodic execution often corresponds to a input data

independent system data flow

– input data is mostly generated with a fixed period(the sample rate)

Embedded System ArchitecturesArchitectures for Data Dominated Systems

General Purpose vs. Application Specific Processors Slide 20Eduard Turcan October 24, 2001

Examples - MMXEmbedded System Architectures

Architectures for Data Dominated Systems

General Purpose vs. Application Specific Processors Slide 21Eduard Turcan October 24, 2001

Examples - Hitachi SH-DSPEmbedded System Architectures

Architectures for Data Dominated Systems

General Purpose vs. Application Specific Processors Slide 22Eduard Turcan October 24, 2001

Examples - Philips Trimedia TM1000Embedded System Architectures

Architectures for Data Dominated Systems

General Purpose vs. Application Specific Processors Slide 23Eduard Turcan October 24, 2001

Examples - TI TMS320C80Embedded System Architectures

Architectures for Data Dominated Systems

General Purpose vs. Application Specific Processors Slide 24Eduard Turcan October 24, 2001

Customized Instruction-Sets

• Instruction-Set Architectures (ISAs) are thevisible instructions of a processor

• Is there a strong motivation for customizingprocessors’ instruction-sets?

Customized Instruction SetsIntroduction

5

General Purpose vs. Application Specific Processors Slide 25Eduard Turcan October 24, 2001

Barriers

• Existing binaries

• Toolchain costs and user familiarity

• Lost savings/higher chip cost due to lowervolumes

• Hardware development costs

• The product development cycle for embeddedproducts

Customized Instruction SetsBarriers

General Purpose vs. Application Specific Processors Slide 26Eduard Turcan October 24, 2001

Co-design Problems

• Instruction-set definition

• Instruction encoding for code compression

• Instruction encoding for memory optimization

• Global control and data flow optimization

• Communication channel selection

• Component interface synthesis

• Component selection/reuse

General Purpose vs. Application Specific Processors Slide 27Eduard Turcan October 24, 2001

Conclusions

?