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Sogang University
Embedded Computer Architecture
Chap 1. Introduction
Hyuk-Jun Lee, PhD
Dept. of Computer Science and EngineeringSogang University
Seoul, Korea
Email: [email protected]
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Contents
• What is Embedded System ?
• Characteristics of Embedded System
• Embedded System Components (H/W, S/W)
• Examples of Embedded Applications
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What is Embedded System ?
• Definition of an Embedded System
– An embedded system is various type of computer system or computing device that performs a dedicated function and/or is designed for use with a specific embedded software application.
– Embedded systems may be built with operating system or without operating system. An embedded system is not generally usable as a commercially viable substitute for general-purpose computers or devices.
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Characteristics of Embedded System
• Application-specific functionality
– Optimal design is possible to fit special purpose.
• Optimized for various metrics
– Performance, e.g. throughput, worst case execution time
– Cost
– Power/energy consumption
– Reliability, e.g. extremely harsh environment, safety critical
– Limited size or resources
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Components (H/W)
• Embedded System H/W
– Processor : handling program instructions
– Memory : saves program and data
– Peripheral device : connecting system and external devices
– Network device
• PC H/W vs. Embedded System H/W
H/W PC Embedded System
Processor High-performance High to low performance
Memory Big capacity High to low capacity
Auxiliary storage Variety : HDD, ODD, DVD, etc.
Sometimes
Peripheral device Variety : Keyboard, Mouse, Speaker, etc.
Under the necessity
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Components (H/W)
• Processor
– Perform execution of programs
– Speed
• hundreds of MHz to GHz clock rate
• 8 bits, 16 bits, 32 bits and 64 bits
– depend on data bus size and basis operation unit
– PC
• Intel, AMD, NVidia
– Embedded System
• ARM, MIPS, Motorola, TI, Samsung, Qualcomm, Apple, Google etc
• Varies based on function complexity as well as system size
• Micro-processor : includes only CPU core (data and control section)
• Micro-controller : includes CPU core, various types/sizes memory
and various peripheral devices
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Components (H/W)
• Memory/Storage
– Main role : saving programs and data
– RAM : Volatile memory
• Used primarily to save large program or data.
• DRAM (Dynamic Random Access Memory)
– Commonly large capacity
– tens of nanoseconds access time
• SRAM (Static Random Access Memory)
– Commonly small capacity
– High speed : Cache memory, place for deterministic memory access
– Sub-nano or a few nanoseconds access time
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Components (H/W)
– Flash Memory : Non-volatile memory
• Read, write (program) or erase operations
• Flash memory is cheap compared to the byte-programmable
EEPROM, but only can erase/write a block at a time.
• Offer faster read/write access time (not as fast as volatile DRAM)
and better shock resistance than hard disks.
– Tens of microseconds for read, Hundreds of microseconds for write, a few
milliseconds for erase
• Gain popularity in portable electronic devices and replace EEPROMs,
and HDD
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Components (H/W)
• I/O devices– Respond to external input, and perform its task.
– Two ways of accessing
• Polling : simple implementations
• Interrupt : efficient implementations
– Input devices
• Keyboard, Mouse, Microphone, Sensor, touchpad etc.
– To convert analog signals to digital information
• Analog signal : analog sensor (ex) temperature
• Need ADC (Analog to Digital Converter).
ex) temperature changing → output temperature (analog sensor)
→ digital signal (ADC) → control program → output to heater
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Components (H/W)
– Output devices
• LED : output signal on/off
• 7-segment : number or alphabet
• LCD : picture, etc.
• Serial port
– RS232C standard
– Connect peripheral device in several meters
– Low speed, simple
• Parallel port
– For close place than serial interface
• Printer interface (speed : about 20KB/sec)
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Components (H/W)
• USB (Universal Serial Bus) / IEEE 1394
– Faster than others
– USB 3.0
• Popular in many devices
• The maximum transfer rate is ~5Gbps
• Printer, scanner, keyboard, joystick, MP3 player, TV etc.
– IEEE 1394 (Firewire by Apple)
• The maximum transfer rate is 400Mbps~3.2 Gbps.
• HDD, CD/CD-RW, video camera, etc.
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Components (H/W)
• Network device
– Control peripheral device far away
– Cable network
• Ethernet
• IEEE 802.3 standard
– Wireless network
• IEEE 802.11 standard (a/b/g/n) - WiFi
• Bluetooth – personal area network(PAN), low power, low BW
• Zigbee - PAN, low power, low BW
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• Sensors
– CCD or CMOS camera sensor
– Haptic/tactile sensor
– Gyro sensor (gyroscope)http://www.youtube.com/watch?v=cquvA_IpEsA
Components (H/W)
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Components (S/W)
• Embedded System S/W
– OS : RTOS (Real-time Operating System),
Embedded Linux
– System S/W : OS API, Network API, etc.
– Application S/W
• PC S/W vs. Embedded System S/W
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Examples of Embedded Applications
• Consumer
– 3D HDTV, Game box
– Home appliances
– Entertainment (Audio/Video)
• Communication
– Smart phone, mobile phone
– Telephone, Answering machines
– Networking (Ethernet, IP routing)
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• Automotive
– Engine Control Unit, Transmission Control Unit
– Power windows, seats
– Safety (airbag, ABS)
– Navigation
Examples of Embedded Applications
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• Military
– Target recognition
– Guidance
– Navigation
• Industrial
– Traffic Control
– Robotics, Production
– Inventory, Stock management
Examples of Embedded Applications
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• Medical
– MRI, CT, Ultrasonic
– Pacer
– Wireless implant
Examples of Embedded Applications
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Tentative Course Outline
• Processor architecture– Review on computer architecture– Metrics and ISA– Instruction level parallelism– ARM processor architecture and code optimization– GPGPU
• Memory System– Basic and advanced cache architecture– Memory systems and virtual memory
• IO devices and operations• Examples for embedded systems
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Teaching Materials
• Main
– Lecture slides
• References
– D.A. Patterson and J.L. Hennessy, Computer Organization and
Design: The Hardware/Software Interface, 4th edition, Morgan
Kaufmann, 2008.
– J.L. Hennessy and D.A. Patterson, Computer Architecture: A
Quantitative Approach, 4th edition, Morgan Kaufmann, 2006.
– ARM System Developer’s Guide, A. Sloss, D. Symes, and C.
Wright, Morgan Kaufmann,2004