임베디드 내장형 시스템 z 교과서 y Computers as components Morgan

임베디드(내장형)시스템 z 교과서 y Computers as components Morgan Kaufmann by Wayne Wolf xwww. mkp. com/embed y Surviving the So. C revolution KAP by Henry Chang et Al. z 평가: 시험 60%, H. W. 20%, 실습 20% z Homepage: http: //vada. skku. ac. kr

임베디드 시스템 개요 z 임베디드 시스템 y특정 목적으로 구성된 하드웨어 위에 소프트웨어 를 내장하여 최적화시킨 시스템 z 임베디드 소프트웨어 y임베디드 시스템에 탑재되는 시스템 소프트웨어, 미들웨어, 응용 소프트웨어를 총칭 z 임베디드 시스템 온 칩 y논리 회로와 메모리, 프로세서등을 집적하여 기본 적인 처리 기능에 입출력, 저장 기능을 포함시켜 시스템을 칩으로 구현한 것.

임베디드 소프트웨어 산업의 발전 동향

내장형시스템 설계 z 강의일정 1. 2. 3. 4. 5. 6. 7. 8. 9. Embedded computing Instruction sets CPUs Embedded computing platform Program design and analysis Processes and operating system Hardware Accelerators Networks System design techniques

So. C 설계 z 강의일정 y 1. 2. 3. 4. 5. 6. Moving to SOC design Overview of the SOC design process Integration platforms and SOC design Function-architecture co-design Designing communications networks Network on Chip Low Power So. C designs

1. Embedded Computing 1. 1 1. 2 1. 3 1. 4 1. 5 Introduction Complex system and microprocessors Embedded system design process Formalisms for system designs Design example: model train controller

1. Introduction z. What are embedded systems? z. Challenges in embedded computing system design. z. Design methodologies.

Definition z. Embedded system: any device that includes a programmable computer but is not itself a general-purpose computer. z. Take advantage of application characteristics to optimize the design: ydon’t need all the general-purpose bells and whistles.

Embedding a computer output CPU embedded computer analog input analog mem

Examples z. Personal digital assistant (PDA). z. Printer. z. Cell phone. z. Automobile: engine, brakes, dash, etc. z. Television. z. Household appliances. z. PC keyboard (scans keys).

Early history z. Late 1940’s: MIT Whirlwind computer was designed for real-time operations. y. Originally designed to control an aircraft simulator. z. First microprocessor was Intel 4004 in early 1970’s. z. HP-35 calculator used several chips to implement a microprocessor in 1972.

Early history, cont’d. z. Automobiles used microprocessor-based engine controllers starting in 1970’s. y. Control fuel/air mixture, engine timing, etc. y. Multiple modes of operation: warm-up, cruise, hill climbing, etc. y. Provides lower emissions, better fuel efficiency.

Microprocessor varieties z. Microcontroller: includes I/O devices, onboard memory. z. Digital signal processor (DSP): microprocessor optimized for digital signal processing. z. Typical embedded word sizes: 8 -bit, 16 bit, 32 -bit.

Application examples z. Simple control: front panel of microwave oven, etc. z. Canon EOS 3 has three microprocessors. y 32 -bit RISC CPU runs autofocus and eye control systems. z. Analog TV: channel selection, etc. z. Digital TV: programmable CPUs + hardwired logic.

Automotive embedded systems z. Today’s high-end automobile may have 100 microprocessors: y 4 -bit microcontroller checks seat belt; ymicrocontrollers run dashboard devices; y 16/32 -bit microprocessor controls engine.

BMW 850 i brake and stability control system z. Anti-lock brake system (ABS): pumps brakes to reduce skidding. z. Automatic stability control (ASC+T): controls engine to improve stability. z. ABS and ASC+T communicate. y. ABS was introduced first---needed to interface to existing ABS module.

BMW 850 i, cont’d. sensor brake ABS hydraulic pump brake sensor

Characteristics of embedded systems z. Sophisticated functionality. z. Real-time operation. z. Low manufacturing cost. z. Low power. z. Designed to tight deadlines by small teams.

Functional complexity z. Often have to run sophisticated algorithms or multiple algorithms. y. Cell phone, laser printer. z. Often provide sophisticated user interfaces.

Real-time operation z. Must finish operations by deadlines. y. Hard real time: missing deadline causes failure. y. Soft real time: missing deadline results in degraded performance. z. Many systems are multi-rate: must handle operations at widely varying rates.

Non-functional requirements z. Many embedded systems are mass-market items that must have low manufacturing costs. y. Limited memory, microprocessor power, etc. z. Power consumption is critical in batterypowered devices. y. Excessive power consumption increases system cost even in wall-powered devices.

Design teams z. Often designed by a small team of designers. z. Often must meet tight deadlines. y 6 month market window is common. y. Can’t miss back-to-school window for calculator.

Why use microprocessors? z. Alternatives: field-programmable gate arrays (FPGAs), custom logic, etc. z. Microprocessors are often very efficient: can use same logic to perform many different functions. z. Microprocessors simplify the design of families of products.

The performance paradox z. Microprocessors use much more logic to implement a function than does custom logic. z. But microprocessors are often at least as fast: yheavily pipelined; ylarge design teams; yaggressive VLSI technology.

Power z. Custom logic is a clear winner for low power devices. z. Modern microprocessors offer features to help control power consumption. z. Software design techniques can help reduce power consumption.

Challenges in embedded system design z. How much hardware do we need? y. How big is the CPU? Memory? z. How do we meet our deadlines? y. Faster hardware or cleverer software? z. How do we minimize power? y. Turn off unnecessary logic? Reduce memory accesses?

Challenges, etc. z. Does it really work? y. Is the specification correct? y. Does the implementation meet the spec? y. Reliability in safety-critical systems

Challenges z. How do we work on the system? y. Complex testing x. How do we test for real-time characteristics? x. How do we test on real data? y. Limited observability and controllability y. Restricted development environments x. What is our development platform?

Design methodologies z. A procedure for designing a system. z. Understanding your methodology helps you ensure you didn’t skip anything. z. Compilers, software engineering tools, computer-aided design (CAD) tools, etc. , can be used to: yhelp automate methodology steps; ykeep track of the methodology itself.

Design goals z. Performance. y. Overall speed, deadlines. z. Functionality and user interface. z. Manufacturing cost. z. Power consumption. z. Other requirements (physical size, etc. )

Levels of abstraction requirements specification architecture component design system integration

Top-down vs. bottom-up z. Top-down design: ystart from most abstract description; ywork to most detailed. z. Bottom-up design: ywork from small components to big system. z. Real design uses both techniques.

Stepwise refinement z. At each level of abstraction, we must: yanalyze the design to determine characteristics of the current state of the design; yrefine the design to add detail.

Requirements z. Plain language description of what the user wants and expects to get. z. May be developed in several ways: ytalking directly to customers; ytalking to marketing representatives; yproviding prototypes to users for comment.

Functional vs. nonfunctional requirements z. Functional requirements: youtput as a function of input. z. Non-functional requirements: ytime required to compute output; ysize, weight, etc. ; ypower consumption; yreliability; yetc.

Our requirements form

Example: GPS moving map requirements I-78 Scotch Road z. Moving map obtains position from GPS, paints map from local database. lat: 40 13 lon: 32 19

GPS moving map needs z. Functionality: For automotive use. Show major roads and landmarks. z. User interface: At least 400 x 600 pixel screen. Three buttons max. Pop-up menu. z. Performance: Map should scroll smoothly. No more than 1 sec power-up. Lock onto GPS within 15 seconds. z. Cost: $500 street price = approx. $100 cost of goods sold.

GPS moving map needs, cont’d. z. Physical size/weight: Should fit in hand. z. Power consumption: Should run for 8 hours on four AA batteries.

GPS moving map requirements form

Specification z. A more precise description of the system: yshould not imply a particular architecture; yprovides input to the architecture design process. z. May include functional and non-functional elements. z. May be executable or may be in mathematical form for proofs.

GPS specification z. Should include: y. What is received from GPS; ymap data; yuser interface; yoperations required to satisfy user requests; ybackground operations needed to keep the system running.

Architecture design z. What major components go satisfying the specification? z. Hardware components: y. CPUs, peripherals, etc. z. Software components: ymajor programs and their operations. z. Must take into account functional and non -functional specifications.

GPS moving map block diagram GPS receiver search engine database renderer user interface display

GPS moving map hardware architecture display frame buffer CPU GPS receiver memory panel I/O

GPS moving map software architecture position database search renderer user interface timer pixels

Designing hardware and software components z. Must spend time architecting the system before you start coding. z. Some components are ready-made, some can be modified from existing designs, others must be designed from scratch.

System integration z. Put together the components. y. Many bugs appear only at this stage. z. Have a plan for integrating components to uncover bugs quickly, test as much functionality as early as possible.

Summary z. Embedded computers are all around us. y. Many systems have complex embedded hardware and software. z. Embedded systems pose many design challenges: design time, deadlines, power, etc. z. Design methodologies help us manage the design process.