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