embedded system:introduction 1 introduction what is an embedded system? embedded system market...
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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