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COMP1321 Digital Infrastructure Richard Henson November 2015
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Week 7: Devices and Embedded Systems n Objectives: Explain what an embedded system is and what it consists of Explain the diversity of use of embedded systems in modern day life, and how this has transformed our society
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What is an “Embedded System? n “A computer on a chip” n Could be an i/o control device n Needs programming to control a peripheral n Requirements: CPU and RAM ROM to store control program(s)
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Feedback Loops n Biggest challenge in a control system is to get data transferred quickly enough to change parameters in sufficient time n Obviously not possible to control a rocket remotely if out in space… embedded systems the only way…
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Embedded Digital Systems for control n To control movement in machines parameters for feedback loops need to be controlled IN REAL TIME n Nothing new… been happening for centuries in analogue systems
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Analogue Control… n The Steam Engine… control of Steam to move piston. Feedback loop? https://www.youtube.com/watch?v=ESfSG2OlQY Q https://www.youtube.com/watch?v=ESfSG2OlQY Q https://www.youtube.com/watch?v=ESfSG2OlQY Q https://www.youtube.com/watch?v=73txXT21aZU https://www.youtube.com/watch?v=73txXT21aZU n The Petrol Engine… control of Spark for Igniting Petrol. Feedback loop? http://www.youtube.com/watch?v=W94iksaQwUo http://www.youtube.com/watch?v=W94iksaQwUo
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Digital Control… n The same effect can be created digitally using a transistor as electronic switch: https://www.youtube.com/watch?v=H2J0lS TYVhQ https://www.youtube.com/watch?v=H2J0lS TYVhQ https://www.youtube.com/watch?v=H2J0lS TYVhQ n What is the feedback loop in this digital system?
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History of Embedded Digital Systems n Not possible before integrated circuits went into production (mid-1960s) n Started with Apollo Project: President Kennedy’s plan to land a man on the moon by end of 1969… first commercial production for US defence (1966)… »“Minuteman” intercontinental ballistic missile
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Early SciFi view of a “control” computer: HAL (1968) n One that controls a space ship, and gets “out of control…” https://www.youtube.com/watch?v =ARJ8cAGm6JE
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And has to be turned off… n http://www.youtube.com/watch ?v=OuEN5TjYRCE http://www.youtube.com/watch ?v=OuEN5TjYRCE http://www.youtube.com/watch ?v=OuEN5TjYRCE
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Programming of Apollo guidance system n Written in Fortran language Formula Translation most popular engineering/technology language before “C” n Later showed to have an almost fatal flaw Apollo 13 near catastrophe…
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“Moon Lander” Program n Retro rockets of falling LEM vehicle n Balanced against moon gravity n Limited amount of fuel… n Version written for BASIC n Most popular early microcomputer game
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What happened to “Moon Lander”? n In reality… start of the embedded system revolution “A small step for man… a giant step for mankind” can be interpreted more broadly n In virtual reality… versions available to present day great introduction to real-time control
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Economics of Embedded Systems n Huge initial development cost!! n Once “chips” go into production, cost falls dramatically… e.g. First Apollo guidance program cost $1000 per chip to implement as soon as mass production started, unit cost was $3 economic driving force behind “Silicon Valley”….
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BBC, 1977 “The Chips are Down”… Silicon Valley, California https://www.youtube.com/wat ch?v=HW5Fvk8FNOQ
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Early Microprocessors n n Two main rival companies: Intel (world’s first, 4004) Motorola (pushed efficiency, through larger bus size…) n n CPU not much of a system on its own… still needed lots of “external” support
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Microcontrollers n Mass produced in late 1980s responsible for “computerisation” of electrical appliances programs held on ROM n Further development of microprocessor & components… n Whole system on a chip… truly an embedded system
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Programming a Microcontroller n Assembly language cumbersome n Fortran shown to be deficient Apollo 13 failure caused by variable not being reinitialised to zero – other languages enable this by default n “C” seen as the way forward: perfected by 1978
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Components of a Microcontroller n e.g. Intel 8048 (1977): CPU RAM Timer chip ROM of some kind i/o capability
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Uses of Microcontrollers n Automatically controlled products and devices: car engine control systems implantable medical devices remote controls office machines Appliances power tools, toys, etc.
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Why are embedded systems so popular? n Reduced size/cost compared to designs that using separate microprocessor, memory, and input/output devices became economical to digitally control ever more devices and processes »embedded systems networkable »even configurable via network… »“intelligent” products now leave the factory with an IP address…
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The Internet of things n Networks often have embedded systems n Why not the Internet…? logical extension of giving each digital device or system a MAC address »generate IP address from this! is this wise with intelligent devices? especially with 3D printers? http://www.youtube.com/watch?v=LRq_SAuQDec http://www.youtube.com/watch?v=LRq_SAuQDec
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Networking Embedded Devices n Two ways to network: Peer-peer »Internet uses peer-peer Client-server »better for centralised control… n How about IoT? »https://www.youtube.com/watch?v=6chnIdEsUeI https://www.youtube.com/watch?v=6chnIdEsUeI
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