Computers embedded in special purpose devices

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25 Νοε 2013 (πριν από 3 χρόνια και 10 μήνες)

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Computers
embedded in
special
purpose
devices

S
kills
: none
C
oncepts
: embedded computer, RAM, ROM, sensor,
the “Internet of things”
This work is licensed under a Creative Commons Attribution
-
Noncommercial
-
Share Alike
3.0 License.
Embedded computers

This presentation introduces computers that
are embedded in special purpose devices.


We see that they have

the same functional
components as general purpose computers,
but you cannot change their function by
loading a new program.


We will see several examples of devices with
embedded computers and the sensors they
use.




A technology
presentation

Where does this topic fit?

Internet concepts

Applications

Technology

Implications

Internet skills

Application development

Content
creation

User skills

This is a technology presentation.



Embedded
computers
have the
same
functional
components
as general
purpose
computers.

Computer
components

information flow
Memory
CPU
Storage
devices
(programs and data)
Input
devices
Output
Devices
system

This diagram stresses the direction of
information flows within a comp
uter.


With a laptop or desktop computer, the user
interacts with the input and output devices, for
example typing information on a keyboard,
pointing at the screen with a mouse, or reading
printed or displayed information.


Computers that are embedded in

special
purpose devices have the same functional
components, but the inputs, outputs or both
are often to and from things, not people.

Devices with
computers
embedded in
them

Things with computers inside
(embedded)

Computers are embedded in all of these
devices
.


Cars, cameras, cell phones, watches, TV sets,
microwave ovens, and ATM machines all
contain embedded computers.





A microwave
oven


Take a microwave oven for example.


When the user pushes the “start” button on a
microwave oven, the embedded computer
detects that it has been pushed and reads the
settings on the control panel.


It then adjusts the power level, sends a signal
to turn the oven on, tracks the elapsed time,
sends a signal to turn the oven off at the pro
per
time, and outputs a beeping sound to let the
user know the food is cooked.


The computer is able to output signals to adjust
the power level and turn the oven on and off.




A camera


There is a computer embedded in this

camera.


It can read input from the various dials and
buttons used to select options.


Light coming through the lens strikes an image
sensor that reads the intensity and color of the
light at each pixel point.


That information is output to the display on

the
back of the camera along with focusing
information.


When the user pushes the shutter button, the
image is stored in flash storage.


The user can connect the camera to a laptop or
desktop and transfer images stored inside the
camera to the computer.


If the camera has a cellular or WiFi radio, it can
also upload stored images to the Internet.



There are
many
computers in
a modern car.

Air
-
bag control
Anti
-
lock brakes
Automatic transmission
Alarm
Climate
control
Collision
-
avoidance
Cruise control
Communication (e. g.,
onStar
)
Dashboard instrumentation
Stability control
Ignition
system
Engine
control
Seat
control
Entertainment system
Navigation
Power steering
Tire
-
pressure
monitoring
Windshield
-
wiper
control
Computers
in cars

This slide lists some of the computer controlled
systems in a modern car.


Dozens of
computers running millions of lines of
software are embedded in modern cars.


They are a major cost component and a possible
source of bugs and vulnerable to hacking.


In spite of that complexity, they make new
features possible and increase safety and
rel
iability.



General
versus
special
-
purpose
computers

General purpose
computer
Special purpose
computer
Programs in volatile,
random access memory
(RAM)
Programs in fixed,
read only memory
(ROM)

When we use our laptop or desktop computers,
we load different programs into memory to do
different jobs


a word processing program for
writing, an image editor for draw
ing, and so forth.


Memory that can be changed is called RAM
(random access) memory.


When you turn the computer off, the contents of
RAM memory are erased


it is volatile.


The programs in an embedded computer don’t
change


your camera is always a

camera, never a
microwave oven.


Since the function does not change, the camera
program is permanently stored in read only
memory (ROM).


ROM contents are permanent.


Flash memory chips are both changeable and non
-
volatile.


That makes flash useful
for both memory and for
storage.


A final point


do not be confused by the term CD
-
ROM.


CD
-
ROM drives are storage devices, and have

nothing to do with ROM memory.


Sensors
gather input
from the
environment

Sensors

With conventional computers, people operate the
input devices


we type, speak into microphones,
scan images, and so forth.


Embedded computers also get input from sensors.


For example, the acceleration sensor in a tablet
computer or cell phone allows

the program to
detect and respond to motion


it knows when the
device is moved or rotated.


The devices shown on the left are temperature
sensors.


They might be used by a computer that controls
heating and air conditioning.


There

are many other typ
es of sensor


Sensors are
input devices
and effectors
output
devices.

Effectors

Embedded computers typically get input from
sensors as well as people and they can control
devices.


This thermostat reads the desired temperature
from a

dial rotated by a user.


It reads the current room temperature using a
temperature sensor.


And it turns the heater or air conditioner by
outputting a command to an effector.


Sensors are input devices from the environment
and effectors are output devices

to the
environment.



The Internet
of things


devices with
embedded
computers
are
increasingly
connected to
the Internet.

The Internet of things

You may hear people speak of “the Internet of
things.”


We interact with computers using our
fingers,
eyes and voices


our senses.


Things interact using light, temperature and other
types of sensors.


More things


from building light and heat
controls to soil moisture detectors to location
trackers on migrating birds


are connected to the
Internet every day.





Summary

Summary
Memory
CPU
Storage
devices
(programs and data)
Input
devices
Output
Devices
system

We saw that many special purpose devices have
computers embedded inside them.


They have the same functional components


input and output devices, memory, storage and
CPU


as general purpos
e computers.


Embedded computers often get input from
sensors and send output to
effectors that
c
ontrol
devices
.


Programs are stored in non
-
volatile, read
-
only
memory on embedded computers.


Devices with embedded computers are
increasingly being connected

to the Internet,
creating an Internet of things.


The Internet of things brings us new applications
and efficiency, but it also exposes us to risks from
program or machine errors or malware.



Self
-
study questions

1.

Is an embedded computer more likely to

keep its program in RAM or ROM? Explain.

2.

What are the input, output and storage devices on a tablet computer?

3.

What are the input, output and storage devices on a smart phone?

4.

Are smart phones special purpose or general purpose computers?

5.

What are the i
nput, output devices of an ATM machine?

6.

Where do ATM machines store information?

7.

Where is the program of an ATM machine?

8.

When you cook

something in a microwave oven for one minute, what is the embedded computer
programmed to do when the time runs out?

9.

We t
alked of sensors for measuring temperature and acceleration. What other type of sensors are available
for today’s computer systems?

10.

Give an example of an effector that is controlled by an embedded computer.

11.

What is some of the information your car can communicate using onStar or Ford Synch?

12.

What are some privacy issues raised by automotive information systems?

Resources

New York Times article on ARM, the leading designer of chips for embedded systems:

http://www.nytimes.com/2010/09/20/technology/20arm.html?_r=1&th&emc=th

ARM Web site, with many examples of embedded applications and an overview of their product line:

http://www.arm.com/

Risks of embedded smart phones:

http://
blogs.mcafee.com/enterprise/mobile/why
-
does
-
my
-
car
-
have
-
its
-
own
-
smartphone

The risk of software error in cars:

http://
www.economist.com/blogs/babbage/2010/05/techview_cars_and_software_bugs

The use of embedded computers in cars:

http://
spectrum.ieee.org/green
-
tech/advanced
-
cars/this
-
car
-
runs
-
on
-
code/0