- Slides: 23
COMP 1321 Digital Infrastructure Richard Henson November 2015
Week 7: Devices and Embedded Systems n Objectives: ØExplain what an embedded system is and what it consists of ØExplain the diversity of use of embedded systems in modern day life, and how this has transformed our society
What is an “Embedded System? “A computer on a chip” n Could be an i/o control device n Needs programming to control a peripheral n Requirements: n ØCPU and RAM ØROM to store control program(s)
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… Øembedded systems the only way…
Embedded Digital Systems for control n To control movement in machines Øparameters for feedback loops need to be controlled IN REAL TIME n Nothing new… been happening for centuries in analogue systems
Analogue Control… n The Steam Engine… control of Steam to move piston. Feedback loop? Ø https: //www. youtube. com/watch? v=ESf. SG 2 Ol. QYQ Ø https: //www. youtube. com/watch? v=73 tx. XT 21 a. ZU Ø n The Petrol Engine… control of Spark for Igniting Petrol. Feedback loop? Ø http: //www. youtube. com/watch? v=W 94 iksa. Qw. Uo
Digital Control… n The same effect can be created digitally using a transistor as electronic switch: Øhttps: //www. youtube. com/watch? v=H 2 J 0 l. S TYVh. Q n What is the feedback loop in this digital system?
History of Embedded Digital Systems Not possible before integrated circuits went into production (mid-1960 s) n Started with Apollo Project: n ØPresident Kennedy’s plan to land a man on the moon by end of 1969… Øfirst commercial production for US defence (1966)… » “Minuteman” intercontinental ballistic missile
Early Sci. Fi 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 =ARJ 8 c. AGm 6 JE
And has to be turned off… n http: //www. youtube. com/watch ? v=Ou. EN 5 Tj. YRCE
Programming of Apollo guidance system n Written in Fortran language ØFormula Translation Ømost popular engineering/technology language before “C” n Later showed to have an almost fatal flaw ØApollo 13 near catastrophe…
“Moon Lander” Program 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 n
What happened to “Moon Lander”? n In reality… Østart of the embedded system revolution Ø“A small step for man… a giant step for mankind” can be interpreted more broadly n In virtual reality… Øversions available to present day Øgreat introduction to real-time control
Economics of Embedded Systems Huge initial development cost!! n Once “chips” go into production, cost falls dramatically… n Øe. g. First Apollo guidance program cost $1000 per chip to implement Øas soon as mass production started, unit cost was $3 Øeconomic driving force behind “Silicon Valley”….
BBC, 1977 “The Chips are Down”… Silicon Valley, California https: //www. youtube. com/wat ch? v=HW 5 Fvk 8 FNOQ
Early Microprocessors n Two main rival companies: ØIntel (world’s first, 4004) ØMotorola (pushed efficiency, through larger bus size…) n CPU not much of a system on its own… Østill needed lots of “external” support
Microcontrollers n Mass produced in late 1980 s Øresponsible for “computerisation” of electrical appliances Øprograms held on ROM Further development of microprocessor & components… n Whole system on a chip… n Øtruly an embedded system
Programming a Microcontroller Assembly language cumbersome n Fortran shown to be deficient n ØApollo 13 failure caused by variable not being reinitialised to zero – other languages enable this by default n “C” seen as the way forward: Øperfected by 1978
Components of a Microcontroller n e. g. Intel 8048 (1977): ØCPU ØRAM ØTimer chip ØROM of some kind Øi/o capability
Uses of Microcontrollers n Automatically controlled products and devices: Øcar engine control systems Øimplantable medical devices Øremote controls Øoffice machines ØAppliances Øpower tools, toys, etc.
Why are embedded systems so popular? n Reduced size/cost compared to designs that using separate microprocessor, memory, and input/output devices Øbecame 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…
The Internet of things Networks often have embedded systems n Why not the Internet…? n Ølogical extension of giving each digital device or system a MAC address » generate IP address from this! Øis this wise with intelligent devices? Øespecially with 3 D printers? Ø http: //www. youtube. com/watch? v=LRq_SAu. QDec
Networking Embedded Devices n Two ways to network: ØPeer-peer » Internet uses peer-peer ØClient-server » better for centralised control… n How about Io. T? » https: //www. youtube. com/watch? v=6 chn. Id. Es. Ue. I