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Embedded System:Introduction

Introduction

• What is an embedded system?

• Embedded system market trends

• Characteristics of embedded systems

• Embedded system requirements

• Design of embedded systems

• Trend of embedded systems

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Embedded System:Introduction

What Is an Embedded System?

• What is a system?– A set or arrangement of things so related or connected as to

form a unity or organic whole.

• What is embedded?– To be set or fixed firmly in a surrounding mass.

• What is an embedded system?– An electronic system embedded within a given plant or

external process to perform a specific function, which has to respond to certain inputs within a prescribed time constraint.

• The external process comprises both a physical system and also humans performing some supervising or parameter setting tasks.

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Embedded System:Introduction

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Embedded System:Introduction

Components of an Embedded System

• Software– Operating systems, device drivers, application programs that

Provide system features and flexibility

• Hardware– Processor cores, DSP cores, ASICs, Memorys, I/O devices,

SOCs (system-on-chip), communication ICs, ADC/DAC, …, are used for achieving the required performance and sometimes the security.

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Embedded System:Introduction

Characteristics

• Perform a single or tightly knit set of functions, which is not usually general purpose, i.e., application specific

• Increasingly high-performance and real-time constraints

• Reactive, i.e., an embedded system (ES) must respond to an input stimulus

• Distributed, i.e., many correlated components (processors) are coordinated to react the input stimuli coming from the various positions of an ES.

• Cost, reliability(long life), power are important attributes in design decision, usually under the constraints of limited hardware resource.

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Embedded System:Introduction

Real-Time Requirements

• A real-time system consists of tasks under deadline constraints– Notion of time typically is global

• Hard real-time versus soft real-time systems– Hard real-time: the tasks must complete by specified

deadlines, e.g., flight control, collision alert, the warning coming from most of the medical equipment, etc.

– Soft real-time: task execution may go beyond specified deadlines without catastrophic failures, .e.g., display update, ...

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Embedded System:Introduction

Applications

• Consumer electronics, e.g., cameras, camcorders, ….• Home appliance, e.g., washers, microwave ovens, ….• Medical instruments, e.g., heart-beat monitor for new-

born, contraction monitor for womb,….• Automobiles, e.g., anti-lock braking, engine control, ….• Industrial process controllers• Avionics and defense systems• Computer/communication products, e.g., network

printers, fax, PDA, cellular phones, software modem, ….

• Multimedia applications, e.g., interactive game boxes, TV set-top-box, ...

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Embedded System:Introduction

Diversified Computing Requirements

• Infrared remote controller– Required least amount of computing power, but optimized for

code size and power

• Pocket remote control RF transmitter– 100 KIPS, optimized for code size and power

• Industrial equipment controller– 1 MIPS, 1 MB memory

– safety-critical

• Military signal processing and multimedia applications– 1 GFLOPS, 1 GB/sec IO, 32 MB

– Software for high performance

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Embedded System:Introduction

Embedded System Market

• Market size for embedded systems: US$ 31 B– General purpose computing: US$ 46.5 B

• Micro-controller market: US$4.6 B, +18% annual growth rate– Versus +10% annual growth rate for general purpose

processors

• Embedded system market will finally surpass computing marketing.

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Embedded System:Introduction

Driving Forces

• Computing technologies are proliferating to non-computing domains– portable devices, medical instrumentation and imaging,

information appliance

• Increasing the need for product personalization– Hand-held devices

• Increasing the need for entertainment– Game boxes

• Advance in semiconductor technologies and design methodologies– reducing manufacturing and design costs

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Embedded System:Introduction

Embedded System Design

• Defining Specifications

• Modeling the system to be designed algorithmically;

• Refining the function to be implemented into smaller interacting pieces;

• HW-SW partitioning by allocating elements in the refined model to either (1) HW units, or (2) SW running on custom hardware or a general processor;

• Scheduling the times at which the functions are executed;

• Mapping a functional description into (1) software that runs on a processor, or (2) a collection of custom, semi-custom, or commodity HW.

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Embedded System:Introduction

Diversified Design Requirements

• Cost• Size• Power• Reliability

– safety-critical – viable for a harsh environment

• Performance• Real-time constraint• Product differentiation• Time to market pressure• Combination of HW and SW

– New design paradigms, techniques, and tools

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Embedded System:Introduction

Embedded System Design

• Defining Specifications

• Modeling the system to be designed algorithmically;

• Refining the function to be implemented into smaller interacting pieces;

• HW-SW partitioning by allocating elements in the refined model to either (1) HW units, or (2) SW running on custom hardware or a general processor;

• Scheduling the times at which the functions are executed;

• Mapping a functional description into (1) software that runs on a processor, or (2) a collection of custom, semi-custom, or commodity HW.

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Embedded System:Introduction

What is HW/SW Co-design?

• The act of bridging the gap between the HW and SW.

• Traditional design approach– SW and HW partitioning is decided at an early stage, and

designs proceed separately from then onward.

• HW/SW co-design– A flexible design strategy, wherein the HW/SW designs

proceed in parallel, with feedback and interaction occurring between the two as the design progresses.

– Final HW/SW partitioning and allocation is made after evaluating trade-offs and performance of options.

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Embedded System:Introduction

CAD for Embedded System Design

• Co-design: Joint optimization of hardware and software– Cost-performance tradeoffs as a part of product

implementation, as opposed to product specification. That is, we can perform design space exploration across the HW and SW boundary

• Co-synthesis: Synthesis assisting co-design– Design derived from (formal) specifications

– Rapid exploration of design alternatives

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Embedded System:Introduction

Disciplines in Embedded System Design

• The design of embedded systems spans several different disciplines in CS and EE

• Application domain (Signal processing,….)

• Software engineering (Programming languages, compilers, …)

• VLSI (computer aided) design

• Parallel/distributed system design– Networking and communications

• Real-time systems (Real-time OS)

• Computer organization and architecture

• Input/output, sensor and actuators technologies, etc.

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Embedded System:Introduction

Trends in Embedded Systems

• Increasing code size– Average code size: 16K~64KB in 1992, 64K~512KB in 1996

– Migration from assembling coding to high-level languages

• Reuse of hardware and software components– Processors (micro-controllers, DSPs)

– Software components (drivers)

• Increasing integration and system complexity– integration of RF, DSP, networking interface

– 32-bit processors, IO processors, Network processors

• Increasing more intelligent

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Embedded System:Introduction

Digital Signal Processing in ES

• Continued digitalization of signals increasing the role of DSP– Signals are represented digitally as sequence of samples

– ADCs are moving closer to signals

• Even RF, IF processing in digital domain

• Typical DSP processing– Filtering, averaging, FFT, device control, etc.

– Speech: codec, processing, user interface, etc

– Communications: modulation, demodulation, noise/echo cancellation, encoding, decoding, equalization, etc.

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Embedded System:Introduction

Example 1

• Nike psa– Delivers up to 120 minutes of digital music.

– Plays either MP3 or WMA digital audio formats downloaded from the Internet.

• Universal Information Appliance

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Embedded System:Introduction

Summary

• What is an embedded system?

• Embedded system market trends

• Characteristics of embedded systems

• Embedded system requirements

• Design of embedded systems

• Trend of embedded systems