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COMP1321
Digital Infrastructure
Richard Henson
November 2015
Week 7: Devices and
Embedded Systems

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?
“A computer on a chip”
 Could be an i/o control device
 Needs programming to control a
peripheral
 Requirements:

CPU and RAM
ROM to store control program(s)
Feedback Loops

Biggest challenge in a control system is
to get data transferred quickly enough
to change parameters in sufficient time

Obviously not possible to control a
rocket remotely if out in space…
embedded systems the only way…
Embedded Digital Systems
for control

To control movement in machines
parameters for feedback loops need to
be controlled IN REAL TIME

Nothing new… been happening for
centuries in analogue systems
Analogue Control…

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=73txXT21aZU


The Petrol Engine… control of Spark for
Igniting Petrol. Feedback loop?
 http://www.youtube.com/watch?v=W94iksaQwUo
Digital Control…

The same effect can be created digitally
using a transistor as electronic switch:
https://www.youtube.com/watch?v=H2J0lS
TYVhQ

What is the feedback loop in this digital
system?
History of Embedded
Digital Systems
Not possible before integrated circuits
went into production (mid-1960s)
 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
Early SciFi view of a “control”
computer: HAL (1968)

One that controls a space ship, and
gets “out of control…”
https://www.youtube.com/watch?v
=ARJ8cAGm6JE
And has to be turned off…

http://www.youtube.com/watch
?v=OuEN5TjYRCE
Programming of
Apollo guidance system

Written in Fortran language
Formula Translation
most popular engineering/technology
language before “C”

Later showed to have an almost fatal
flaw
Apollo 13 near catastrophe…
“Moon Lander” Program
Retro rockets of falling LEM vehicle
 Balanced against moon gravity
 Limited amount of fuel…
 Version written for BASIC
 Most popular early microcomputer
game

What happened to
“Moon Lander”?

In reality…
start of the embedded system revolution
“A small step for man… a giant step for
mankind” can be interpreted more broadly

In virtual reality…
versions available to present day
great introduction to real-time control
Economics of
Embedded Systems
Huge initial development cost!!
 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”….
BBC, 1977
“The Chips are Down”…
Silicon Valley, California
https://www.youtube.com/wat
ch?v=HW5Fvk8FNOQ
Early Microprocessors

Two main rival companies:
Intel (world’s first, 4004)
Motorola (pushed efficiency, through larger
bus size…)

CPU not much of a system on its own…
still needed lots of “external” support
Microcontrollers

Mass produced in late 1980s
responsible for “computerisation” of
electrical appliances
programs held on ROM
Further development of microprocessor
& components…
 Whole system on a chip…

truly an embedded system
Programming a
Microcontroller
Assembly language cumbersome
 Fortran shown to be deficient

Apollo 13 failure caused by variable not
being reinitialised to zero – other
languages enable this by default

“C” seen as the way forward:
perfected by 1978
Components of a
Microcontroller

e.g. Intel 8048 (1977):
CPU
RAM
Timer chip
ROM of some kind
i/o capability
Uses of Microcontrollers

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?

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…
The Internet of things
Networks often have embedded systems
 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
Networking Embedded
Devices

Two ways to network:
Peer-peer
» Internet uses peer-peer
Client-server
» better for centralised control…

How about IoT?
» https://www.youtube.com/watch?v=6chnIdEsUeI