Embedded systems - Sushant Kumar - WordPress.com

actuallyabandonedElectronics - Devices

Nov 15, 2013 (3 years and 11 months ago)

96 views

Embedded Systems




By Sushant Kumar

Structure of the seminar

Introduction


History of embedded systems


Characteristics


Embedded systems for meters

Introduction

Part 1

What is an
Embedded System

?

An
embedded system

is a
special
-
purpose

computer system
designed to perform a
dedicated

function

An Embedded system

A generic embedded system

Why Embedded system ?

Performance


Technology Advances


CMOS VLSI dominates older technologies (TTL, ECL)


Computer architecture improvements


RISC, superscalar, RAID, …


Price


Simpler development


CMOS VLSI: smaller systems, fewer components


Higher volumes


CMOS VLSI : same device cost 10,000 vs. 10,000,000
units

Embedded system
vs

General Computer

Performs one or a few pre
-
defined tasks



Very specific requirements



Task
-
specific hardware and mechanical parts


Often mass
-
produced



Design engineers can optimize it

Embedded System

Microprocessor

Micro controller

Micro controllers

have built in peripherals and memory

which reduces the size of the system

Application Areas

Signal processing systems


Real
-
time video, DVD players, Medical equipment.

Distributed control


Network routers, switches, firewalls,

“Small” systems


Mobile phones, home appliances, toys, smartcards, MP3 players,
PDAs, digital cameras, sensors, pc keyboard & mouse

Modern cars:

Up to 100 or more processors


Engine control unit


ABS systems (Anti Lock Brake systems)


Emissions control


Diagnostics and Security systems


Accessories (doors, windows etc)

History of Embedded Systems

Part 2

Apollo Guidance computer

The Apollo Guidance Computer, the first recognizable

modern embedded system

developed by
Charles Stark
Draper

at the MIT Instrumentation Laboratory


Minuteman Missile
1966

First
mass
-
produced

embedded system

Autonetics D
-
17

guidance computer

Built from transistor logic

Reduced prices on nand gate ICs from
$1000/each to $3/each

Medicinal appliances

Avionics, such as inertial guidance systems,
flight control systems

Cellular telephones and telephone switches

Home automation products

Other developments

First Microprocessor

Intel 4004

Required external
memory and support
chips

By mid 1980’s micro
controllers came into
existence

cost of a
microcontroller fell
below
$1


By the end of the 80s,
embedded systems
were the norm rather
than the exception

Moore’s law

Characteristics of Embedded
Systems

Part 2

Characteristics of Embedded Systems

1.
Interface

2.
Complexity

3.
Platform

4.
Peripherals

5.
Tools

6.
Reliability

7.
Volume


1.

Interface

Interface

No User


Interface

Full User


Interface

Performing
user
-

defined


PDA’s

Dedicated to
one

Task

Missile guidance

system

2.

Complexity

Complexity

Simple systems

Complex systems


Use buttons,small
character/ digit
-
only
displays



simple menu system


Connected to a network



Touch screen



Real time constraints



Part of a critical operation

3.

CPU Platform

Many different CPU architectures used
in embedded designs such as ARM,
MIPS, x86, PIC, 8051 etc…


Desktop computer market is limited to
just a few architectures


CPU Platform…

PC/104 is a typical base for small, low
-
volume embedded system design.


Uses an embedded real
-
time operating
system such as MicroC/OS
-
II, QNX or
VxWorks

CPU Platform…

Very
-
high
-
volume embedded systems
use the
system on a chip (SoC),

an
application
-
specific integrated circuit
(ASIC)


CPU core was purchased and added as
part of the chip design.

4.

Peripherals

Serial Communication Interfaces

Universal Serial Bus (
USB
)

Networks:
Ethernet, Controller Area Network

Timers:

PLL(s), Capture/Compare and Time Processing Units

General Purpose Input/Output (
GPIO
)

Analog to Digital/Digital to Analog (
ADC/DAC
)


5.

Tools

Embedded system designers use
compilers
, assemblers, and debuggers

Utilities to add a
checksum

or
CRC

to a
program

Emulator

replaces the microprocessor
with a simulated equivalent

6.

Reliability issues

System cannot be shut down for repair


Solutions involve subsystems with
spares


system must be kept running for safety
and monetary reasons

7.

Volume

Volume

High Volume

Low Volume

Minimizing
cost

is
usually the primary
design consideration


Used when cost is
not

a major factor


Performance and
reliability
constraints

Embedded systems for
Meters

Part 4

Electric power consumption

Electric power consumption is not
constant whole day

Peak period is between 1 pm and 4 pm

System must be engineered to meet
peak power


Limitations of the meter

Mechanical device

Prone to wear,shock

Maintains no record of time

Only Counts the number of rotations of
the wheel


Demand Curve

Real power limitation

Ideally current and voltage are in phase

Every volt
-
ampere delivered becomes a
watt of power used

Induction motors and lamp ballasts
cause current to flow out of phase

Fewer actual watts are used than
delivered

Ideal power curve

When current and voltage are not in
-
phase

Power factor penalty

Industrial customers must by contract
maintain power factor

Power factor=Ratio of real power used
to volt amperes delivered

Pay penalty if above some agreed upon
values

Multi function meter

Extend for smaller commercial customer


Even for residences


Contract can be varied


Billing

Networked system can facilitate
automation

No need to send personnel

Better accuracy and lesser burden

Design Fundamentals

1.
Means of taking samples

2.
Display

3.
Communication subsystem

4.
Non
-
volatile memory

5.
Power supply

6.
Stored program micro
-
controller


Hardware design

Choosing a micro
-
controller

Feature set

Code space

Data Space

Data converter

Real
-
time clock

Conclusion

A quiet revolution is in progress in the
utility industry.

Static metering devices, have been in
use for the better part of a century

Gradually being replaced with multi
-
rate, multifunction meters

Capable of more accurately accounting
for utility usage.

References

www.maxim
-
ic.com

www.electronicsforu.com

www.refdesign.techonline.com

www.wikipedia.org

www.powerelectronics.com

www.ucpros.com

www.pdfserv.maxim
-
ic.com

For detailed report

www.sushantkumar.wordpress.com/tech

Thank You