Thiết kế hệ thống Nhúng chương 1

8/16/2016 ĐẠI HỌC QUỐC GIA TP.HỒ CHÍ MINH TRƯỜNG ĐẠI HỌC BÁCH KHOA KHOA ĐIỆN-ĐIỆN TỬ BỘ MÔN KỸ THUẬT ĐIỆN TỬ Embedded System Design Chapter 1: Embedded System Overview What is an embedded system? Embedded system models Embedded system features Real-time embedded system 1 What’s an Embedded System? • Embedded systems = – information processing systems that interact with physical processes and are embedded into a larger product • Two types of computing – Desktop – produced millions/year – Embedded – billions/year • Non-Embedded Systems – PCs, servers, and notebooks • The future of computing! – Automobiles, entertainment, communication, aviation, handheld devices, military, medical equipment … Bộ môn Kỹ Thuật Điện Tử - ĐHBK Chapter 8/16/2016 What is an embedded system? • Embedded system is – any device that includes a programmable computer but is not itself a general-purpose computer - Wayne Wolf – An embedded computer system includes a micro-computer with mechanical, chemical and electrical devices attached to it, programmed for a specific dedicated purpose, and packaged as a complete system Jonathan W Valvano – An embedded system is one that has computer-hardware with software embedded in it as one of its most important component - Raj Kamal Bộ môn Kỹ Thuật Điện Tử - ĐHBK Chapter Embedded System Examples • The refrigerator – – – – – Maintain a moderately stable, low temperature within it Sense its internal temperature and compare that with the temperature required Lowers the temperature by switching on a compressor The temperature measurement requires one or more sensors Controlling the compressor requires some form of electronic interface Bộ môn Kỹ Thuật Điện Tử - ĐHBK Chapter 8/16/2016 Embedded System Examples • A car door mechanism – Window stall sensor, door sensor – Window motor, lock actuator – Window control buttons Bộ môn Kỹ Thuật Điện Tử - ĐHBK Chapter Embedded System Examples • The Derbot Vehicle – Two microswitch bump detectors – an untrasound detector – Two light sensors – a servo actuator • Derbot is powered from six AA Alkaline cells Bộ môn Kỹ Thuật Điện Tử - ĐHBK Chapter 8/16/2016 Embedded System Examples • The Derbot Vehicle – operates as an embedded system – reading in values from its diverse sensors and computing outputs to its actuators Bộ môn Kỹ Thuật Điện Tử - ĐHBK Chapter Embedded System Models Application software layer System software layer Hardware layer • Application software: – application programs, GUI, control programs… • System software – Operating system, system drivers, system library • Hardware – Processors, memory, peripherals, input/output devices, PCB … Bộ môn Kỹ Thuật Điện Tử - ĐHBK Chapter 8/16/2016 Embedded System Features Components of Embedded Systems Clock Display Power Peripherals Embedded software ROM Embedded Processor Buttons Sensors RAM A/D I/O Actuators • Embedded processor is a heart of the embedded system: – micro-processor: 8086, ARM7, ARM9… – micro-controller: 8051, ARM Cortex-M, PIC16F, 68HC11, Bộ môn Kỹ Thuật Điện Tử - ĐHBK Chapter Embedded System Features • Memory – ROM: embedded program – RAM: processing data • Embedded program – OS / non-OS supported – realtime / non-realtime – timer, interrupt, serial port… • Clock: – crystal • Power: – +5V / +3.3V / +2.5V Bộ môn Kỹ Thuật Điện Tử - ĐHBK Chapter 10 8/16/2016 Embedded System Features • Peripherals: – – – – – I/O port UART I2C ADC PWM • User interface: – Button / keypad / switch – LCD / 7-segment LED / LED indicator • Sensors: – temperature, light, ultrasound, pressure, … • Actuators: – motor, solenoid, relay, … Bộ môn Kỹ Thuật Điện Tử - ĐHBK Chapter 11 Embedded System Features Common Characteristics: • Single-functioned – Executes a single program, repeatedly • Tightly-constrained – Low cost, low power, small, fast, etc • Reactive and real-time – Continually reacts to changes in the system’s environment – Must compute certain results in real-time without delay Bộ môn Kỹ Thuật Điện Tử - ĐHBK Chapter 12 8/16/2016 An embedded system example A digital camera Digital camera chip CCD CCD preprocessor Pixel coprocessor D2A A2D lens JPEG codec Microcontroller Multiplier/Accum DMA controller Memory controller • • • Display ctrl ISA bus interface UART LCD ctrl Single-functioned always a digital camera Tightly-constrained Low cost, low power, small, fast Reactive and real-time: needs to respond to the pressing of buttons by a user Bộ môn Kỹ Thuật Điện Tử - ĐHBK Chapter 13 Embedded System Features Common Characteristics: • Single-functioned – Executes a single program, repeatedly • Tightly-constrained – Low cost, low power, small, fast, etc • Reactive and real-time – Continually reacts to changes in the system’s environment – Must compute certain results in real-time without delay Bộ môn Kỹ Thuật Điện Tử - ĐHBK Chapter 14 8/16/2016 Embedded System Requirements • basic requirements for an embedded system Real-time/ reactive operation Cost / resource Small size/ low weight Safe and reliable Bộ môn Kỹ Thuật Điện Tử - ĐHBK Low power, cooling Chapter 15 Embedded System Quality • basic dimensions of quality Performance: The primary operating characteristics of a product Feature: Those characteristics that supplement a product’s basic functions Reliability: The probability of a product malfunctioning Durability: A measure of the amount of use one gets from a product before it breaks down Serviceability: Ease and time to repair after breakdown Conformance: the degree to meet standards Aesthetics: How a product looks Perceived quality: This dimension is associated with reputation Bộ môn Kỹ Thuật Điện Tử - ĐHBK Chapter 16 8/16/2016 Real-time Embedded Systems • Definition: – A real-time system is one that must process information and produce a response within a specified time – Any system in which the time at which output is produced is significant • Almost embedded systems are real-time Bộ môn Kỹ Thuật Điện Tử - ĐHBK Chapter 17 Real-time Embedded Systems • Hard real-time system: – missing a deadline is a total system failure – Many of these systems are considered to be safety critical – In general there is a cost function associated with the system Bộ môn Kỹ Thuật Điện Tử - ĐHBK Chapter 18 8/16/2016 Real-time Embedded Systems • Soft real-time – the system's quality of service degrades after its deadline – Deadline overruns are tolerable, but not desired – Often connected to Quality-of-Service (QoS) Bộ môn Kỹ Thuật Điện Tử - ĐHBK Chapter 19 Real-time Embedded Systems Examples • Hard real-time system – a car engine control system is a hard real-time system because a delayed signal may cause engine failure or damage – heart pacemakers is hard real-time systems • Soft real-time system – Multimedia systems – LED display control systems Bộ môn Kỹ Thuật Điện Tử - ĐHBK Chapter 20 10 8/16/2016 Quiz What is an embedded system? What is the model of an embedded system? What are embedded system features? What are five basic requirements of an embedded system? What are eight dimension of quality of an embedded system? What are common characteristics of an embedded system? What is real-time embedded system? Give example What is the most importance part of an embedded system? What are differences between hard and soft real-time systems? Bộ môn Kỹ Thuật Điện Tử - ĐHBK Chapter 21 11