COMP1321 Digital Infrastructure Richard Henson December 2013

Week 9: 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

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)

Embedded Digital Systems for control n No longer a simulation of reality…  parameters need to be controlled IN REAL TIME n Been happening for centuries in analogue systems such as steam engine, petrol engine, etc.  saQwUo saQwUo saQwUo

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…

Early SciFi view of a “control” computer: HAL OuEN5TjYRCE

History of Embedded Digital Systems n n Not possible before integrated circuits went into production (mid-1960s) n 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

Programming of Apollo guidance system n n Written in Fortran language   Formula Translation   most popular engineering/technology language before “C” n n Later showed to have an almost fatal flaw   Apollo 13 near catastrophe…

“Moon Lander” Program n n Retro rockets of falling LEM vehicle n n Balanced against moon gravity n n Limited amount of fuel… n n Version written for BASIC n n Most popular early microcomputer game

What happened to “Moon Lander”? n 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 n In virtual reality…   versions available to present day   great introduction to real-time control

Economics of Embedded Systems n n Huge initial development cost!! n 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”….

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

Microcontrollers n n Mass produced in late 1980s   responsible for “computerisation” of electrical appliances   programs held on ROM n n Further development of microprocessor & components… n n Whole system on a chip…   truly an embedded system

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

Components of a Microcontroller n e.g. Intel 8048 (1977):  CPU  RAM  Timer chip  ROM of some kind  i/o capability

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.

Why are embedded systems so popular now?   Reduced the size and cost compared to designs that uses a separate microprocessor, memory, and input/output devices   Therefore economical to digitally control ever more devices and processes » »if have a comms module, embedded systems configurable via network…   “Intelligent” products now leave the factory with an IP address…

The Internet of things   A logical extension of giving digital devices IP addresses » »is this wise with intelligent devices? » »especially with 3D printers   Is this wise… (lol) » ec echttp:// ec

Linking of Devices n Two fundamentally different arrangements:  Peer-peer  Client-server n The latter is better for centralised control… n The Internet uses peer-peer