Main project report on GSM BASED WIRELESS NOTICE BOARD

i

Main project report on

GSM BASED WIRELESS NOTICE BOARD

Submitted in partial fulfillment of main project for the award of the degree of

BACHELOR OF TECHNOLOGY

IN

ELECTRONICS AND COMMUNICATION ENGINEERING

Submitted By

K.NAVYA REGD.NO:11631A0449

S.HARI KRISHNA REGD.NO:11631A0421

P.GANESH REGD.NO:11631A0418

N.RAJIV REGD.NO:11631A0458

Under the esteemed guidance of

B.SWETHA M.Tech

Department of Electronics & Communication Engineering

SRI VENKATESWARA ENGINEERING COLLEGE

Amaravadi Nagar, Sponsored by the exhibition society, HYDERABAD, Approved by AICTE,

Affiliated to Jawaharlal Nehru Technological University, HYDERABAD, Suryapet-508213,

Nalgonda Dist. 2014-2015

ii

SRI VENKATESWARA ENGINEERING COLLEGE

Amaravadi Nagar, Sponsored by The Exhibition Society, HYDERABAD, Approved by AICTE, Affiliated to

Jawaharlal Nehru Technological University, Hyderabad Suryapet-508213, Nalgonda Dist.

2014-2015

Department of Electronics & Communication Engineering

CERTIFICATE

This is to certify that the project report titled as “GSM BASED WIRELESS

NOTICE BOARD” being submitted by K.NAVYA (11631A0449), S.HARI

KRISHNA (11631A0421), P.GANESH (11631A0418), and N.RAJIV (11631A0458)

from IV B.Tech II semester of Electronics and Communication Engineering is a

record bonafide work carried out by us. The results embodied in this report have not been

submitted to any other University for the award of any degree.

Signature of the Guide Signature of the H.O.D

Signature of the External Signature of the principal

iii

DECLARATION

We the Students of B.Tech in ELECTRONICS & COMMUNICATION

ENGINEERING of Sri Venkateswara Engineering College, Suryapet, hereby declare that

the project with title “GSM BASED WIRELESS NOTICE BOARD” Is the original

work done by us.

To the Best of us Knowledge and belief we hereby declare that this project bears

no resemblance to any other project submitted at Sri Venkateswara Engineering College,

Suryapet or any other college affiliated to Jawaharlal Nehru Technological University,

Hyderabad for the award of the degree.

Place:

Date:

Project associates

K.NAVYA - 11631A0449

S.HARI KRISHNA - 11631A0421

P. GANESH - 11631A0418

N.RAJIV - 11631A0458

iv

ACKNOWLEDGEMENT

we sincerely thank our principal Dr.A.SRUJANA for her timely suggestions,

which helped me to complete this work successfully.

It is my privilege to thank Dr.K.MADHAVI, Professor & HOD of ECE

Department for her encouragement during the progress of this project work.

we express my sincere thanks to my supervisor B. SWETHA for giving me moral

support, kind attention and valuable guidance to me throughout this project work.

we thank to both teaching and non-teaching staff members of ECE Department

for their kind cooperation and all sorts of help to bring out this project work successfully.

By

K.NAVYA - 11631A0449

S.HARI KRISHNA - 11631A0421

P. GANESH - 11631A0418

N.RAJIV - 11631A0458

v

ABSTRACT

Scrolling display board is a common sight today. Advertisement is going digital.

The use of LED scrolling display board at big shops, shopping centers, railway station,

bus stands and educational Institutes are becoming an effective mode of communication

in providing information to the people. But these off-the-shelf units are somewhat

inflexible in terms of updating the message instantly. If the user wants to change the

message it needs to be done using a computer and hence the person needs to be Present at

the location of the display board. It means the message cannot be changed from wherever

or whenever. Also the display board cannot be placed anywhere because of complex and

delicate wiring.

‘GSM based LED Scrolling Display Board’ is a model for displaying

notices/messages at places that require real-time noticing, by sending messages in the

form of SMS through mobile. The project aims to develop a moving sign board which

empowers the user to change the scrolling message using SMS service instantaneously

unlike a deskbound device such as PC or laptop. The user can update it even from a

remote distant. The SMS is deleted from the SIM each time it is read, thus making room

for the next SMS.

vi

INDEX

CONTENTS PAGE NO

CHAPTER-1 INTRODUCTION

1.1 EMBEDDED SYSTEMS 1

1.2 CHARACTERISTICS OF EMBEDDED SYSTEMS 1

1.3 APPLICATIONS 2

1.4 CLASSIFICATION 2

1.4.1 RTS CLASSIFICATION 2

1.4.1.1 HARD REAL TIME SYSTEM 2

1.4.1.2 SOFT REAL TIME SYSTEM 3

CHAPTER-2 GSM BASED LED SCROLLING DISPLAY BOARD 4

CHAPTER-3 HARDWARE COMPONENTS 7

3.1 POWER SUPPLY 7

3.1.1 TRANSFORMER 7

3.1.2. IDEAL POWER EQUATION 8

3.1.3. VOLTAGE REGULATOR 7805 9

3.1.3.1 INTERNAL BLOCK DIAGRAM 10

3.1.3.2 ABSOLUTE MAXIMUM RATINGS 10

3.1.4 RECTIFIER 11

3.1.5 FILTER 11

3.2 INTRODUCTION TO LPC2148 MICROCONTROLLER 12

3.2.1 INTRODUCTION 12

3.2.2 FEATURES 13

3.2.3 APPLICATIONS 14

3.2.4 ARCHITECTURAL OVERVIEW 14

3.2.5 ARM7TDMI-S PROCESSOR 14

3.2.5.1 ON-CHIP FLASH MEMORY SYSTEM 15

3.2.5.2 ON-CHIP STATIC RAM (SRAM) 15

3.2.6 BLOCK DIAGRAM 17

vii

3.2.6.1 MEMORY MAPS 18

3.2.7 GENERAL PURPOSE INPUT OUTPUT PORTS 20

3.2.7.1 FEATURES 20

3.2.7.2 APPLICATIONS 20

3.2.8 LPC2148 PIN CONNECT BLOCK 21

3.2.8.1 FEATURES 21

3.2.8.2 APPLICATIONS 21

3.2.8.3DESCRIPTION 21

3.2.8.4 REGISTER DESCRIPTION 22

3.2.8.5 LPC2148 PINOUT 22

3.3 GSM TECHNOLOGY 23

3.3.1 TIME-DIVISION MULTIPLE ACCESS (TDMA) 23

3.3.2 GLOBAL SYSTEM FOR MOBILE COMMUNICATION 24

3.3.3 THE GENERATIONS OF MOBILE NETWORKS 26

3.3.4 HISTORY OF GSM 27

3.3.4.1 ARCHITECTURE OF THE GSM NETWORK 29

3.3.4.2 MOBILE STATION 29

3.3.4.3 BASE STATION SUBSYSTEM 30

3.3.4.4 NETWORK SUBSYSTEM 30

3.3.4.5 GSM FREQUENCIES USING AROUND

THE WORLD 31

3.3.5 GSM SECURITY 32

3.3.5.1 SOME DEFINITIONS 32

3.3.5.2 USER AND SIGNALING DATA

CONFIDENTIALITY 35

3.3.5.3 SUBSCRIBER IDENTITY CONFIDENTIALITY 35

3.3.5.4 SOLUTIONS TO CURRENT

SECURITY ISSUES 36

3.3.5.5 SHORT MESSAGE SERVICE 36

3.4 MAX232 IC 36

3.4.1 FUNCTIONS OF PINS 38

viii

3.5 LIGHT-EMITTING DIODE 39

3.5.1 TECHNOLOGY 40

3.5.2 ADVANTAGES 41

3.5.3 DISADVANTAGES 42

3.5.4 APPLICATIONS 44

CHAPTER-4 SOFTWARE REQUIREMENTS 45

4.1 INTRODUCTION TO KEIL MICRO VISION (IDE) 45

4.2 CONCEPT OF COMPILER 45

4.3 CONCEPT OF CROSS COMPILER 46

4.4 KEIL C CROSS COMPILER 46

4.5 BUILDING APPLICATIONS IN µVISION2 46

4.6 CREATING YOUR OWN APPLICATION IN µVISION 47

4.7 DEBUGGING AN APPLICATION IN µVISION2 47

4.8 STARTING µVISION2AND CREATING A PROJECT 47

4.9 WINDOW-FILES 48

4.10 BUILDING PROJECTS AND CREATING HEX FILES 48

4.11 CPU SIMULATION 48

4.12 DATABASE SELECTION 48

4.13 START DEBUGGING 49

4.14 DISASSEMBLY WINDOW 49

4.15 EMBEDDED C 50

CHAPTER-5 SCHEMATIC DIAGRAM 51

CHAPTER-6 PROJECT CODE 52

6.1 SOURCE CODE 52

CHAPTER-7 ADVANTAGES AND APPLICATIONS 59

7.1 ADVANTAGES 59

7.2 DISADVANTAGES 59

7.3 APPLICATIONS 59

7.4 FUTURE SCOPE 59

CHAPTER-8 CONCLUSION 60

CHAPTER-9 BIBLIOGRAPHY 61

ix

LIST OF FIGURES

FIGURE NO NAME OF THE FIGURE PAGE NO

2.0 BLOCK DIAGRAM OF E-NOTICE BOARD 5

3.1.1 A TYPICAL TRANSFORMER 7

3.1.2 IDEAL POWER EQUATION 8

3.1.3.0 CIRCUIT DIAGRAM OF

VOLTAGE REGULATOR 9

3.1.3.2 BLOCK DIAGRAM OF VOLTAGE

REGULATOR 10

3.1.4 BRIDGE RECTIFIER 11

3.1.6 FILTER OUTPUT 12

3.2.6 BLOCK DIAGRAM OF MICRO CONTROLLER 17

3.2.6.1 SYSTEM MEMRORY MAP 18

3.2.6.2 PERIPHERAL MEMORY MAP 19

3.2.8.3 PIN CONNECT BLOCK REGISTER MAP 22

3.2.8.5 LPC2148 22

3.3 GSM 23

3.3.2 GLOBAL SYSTEM FOR MOBILE

COMMUNICATION 25

3.3.4.1 GENERAL ARCHITECTURE OF

A GSM NETWORK 29

3.3.4.5 GSM FREQUENCIES USING AROUND

THE WORLD 32

3.3.4.1 BASE OF THE SECURITY MECHANISM. 33

3.3.4.2 SUBSCRIBER IDENTIFICATION PROCESS. 34

3.3.4.3. CALCULATING THE SECURITY TRIPLETS. 34

3.3.4.4 AUTHENTICATION THE SUBSCRIBER 35

3.4.0 MAX232N 37

3.4.1 PIN DIAGRAM OF MAX232N 37

5.0 SCHEMATIC DIAGRAM OF E NOTICE BOARD 51

x

LIST OF TABLES

TABLE NO NAME OF THE TABLE PAGE NO

3.1.3.3 RATING OF THE VOLTAGE REGULATOR 10

3.4.2 FUNCTION OF PINS 38

xi

ABBREVIATIONS

ALTERNATING CURRENT AC

DIRECT CURRENT DC

BROWN-OUT DETECT BOD

REAL-TIME CLOCK RTC

ADVANCED HIGH-PERFORMANCE BUS AHB

ADVANCED PERIPHERAL BUS APB

REDUCED INSTRUCTION SET COMPUTER RISC

IN APPLICATION PROGRAMMING IA

IN SYSTEM PROGRAMMING ISP

STATIC RAM SRAM

LOW POWER CONSUMPTION LPC

TIME-DIVISION MULTIPLE ACCESS TDMA

FREQUENCY DIVISION MULTIPLE ACCESS FDMA

GLOBAL SYSTEM FOR MOBILE COMMUNICATION GSM

GENERAL PACKET RADIO SERVICES GPRS

ENHANCED DATA RATES FOR GSM EVOLUTION EDGE

THIRD GENERATION 3G

FOURTH GENERATION 4G

SECOND GENERATION 2G

3RD GENERATION PARTNERSHIP PROJECT 3GPP

AMERICAN PERSONAL COMMUNICATIONS APC

ADVANCED MOBILE PHONE SYSTEM AMPS

INTEGRATED SERVICES DIGITAL NETWORK ISDN

PERSONAL DIGITAL CELLULAR PDC

CONFERENCE OF POSTAL AND TELECOMMUNICATIONS

ADMINISTRATIONS CEPT

EUROPEAN TELECOMMUNICATIONS STANDARDS INSTITUTE ETSI

MULTIMEDIA MESSAGING SERVICES MMS

MOBILE SERVICES SWITCHING CENTER MSC

xii

MOBILE STATION MS

SUBSCRIBER IDENTITY MODULE SIM

INTERNATIONAL MOBILE EQUIPMENT IDENTITY IMEI

INTERNATIONAL MOBILE SUBSCRIBER IDENTITY IMSI

BASE TRANSCEIVER STATION BTS

BASE STATION CONTROLLER BSC

SIGNALING SYSTEM NUMBER 7 SS7

HOME LOCATION REGISTER HLR

VISITOR LOCATION REGISTER VLR

EQUIPMENT IDENTITY REGISTER EIR

AUTHENTICATION CENTER AUC

MOBILE COUNTRY CODE MCC

MOBILE NETWORK CODE MNC

MOBILE SUBSCRIBER IDENTIFICATION CODE MSIC

RANDOM NUMBER RAND

SIGNED RESPONSE SRES

CIPHERING KEY KC

TEMPORARY MOBILE SUBSCRIBER IDENTITY TMSI

SHORT MESSAGE SERVICE SMS

LIGHT-EMITTING DIODE LED

POWER-ON RESET POR

ULTRA-HIGH-FREQUENCY UHF

ANALOG-TO-DIGITAL CONVERSION ADC


INTEGRATED DEVELOPMENT ENVIRONMENT IDE

LOW PROFILE QUAD FLAT PACKAGE LQFP

UNIVERSAL SERIAL BUS USB

DIRECT MEMORY ACCESS DMA

UNIVERSAL ASYNCHRONOUS RECEIVER/TRANSMITTER UART

THUMB INSTRUCTION DEBUGGER MULTIPLIER TDMI

xiii

INTERNATIONAL CONFERENCE ON ENVIRONMENTAL

RESEARCH AND TECHNOLOGY I CE RT

ADVANCED PERIPHERAL BUS APB

INTERIM STANDARD IS

GENERAL PACKET RADIO SERVICE GPRS

ENHANCED DATA-RATES FOR GLOBAL EVOLUTION EDGE

LONG TERM EVOLUTION LTE

UNIVERSAL MOBILE TELECOMMUNICATIONS SYSTEM UMTS

INTENTIONAL ELECTRO-MAGNETIC INTERFERENCE IEMI

SUBSCRIBER IDENTITY MODULE SIM


PUBLIC SWITCHED TELEPHONE NETWORK PSTN



HIGH INTENSITY DISCHARGE HID

CODE DIVISION MULTIPLE ACCESS DMA

HIGH SPEED DATA PACKET ACCESS HSDPA

HIGH SPEED UPLINK PACKET ACCESS HSUPA

ELECTRONIC INDUSTRIES ALLIANCE/TELECOMMUNICATION

INDUSTRIES ASSOCIATION EIA/TIA


SVES 1 ECE Dept.

CHAPTER-1

INTRODUCTION

1.1 EMBEDDED SYSTEMS

An Embedded System is a combination of computer hardware and software, and

perhaps additional mechanical or other parts, designed to perform a specific function.

An embedded system is a microcontroller-based, software driven, reliable, real-time

control system, autonomous, or human or network interactive, operating on diverse

physical variables and in diverse environments and sold into a competitive and cost

conscious market.

An embedded system is not a computer system that is used primarily for

processing, not a software system on PC or UNIX, not a traditional business or

scientific application. High-end embedded & lower end embedded systems. High-end

embedded system - Generally 32, 64 Bit Controllers used with OS. Examples Personal

Digital Assistant and Mobile phones etc.Lower end embedded systems - Generally 8,16

Bit Controllers used with an minimal operating systems and hardware layout designed

for the specific purpose. Examples Small controllers and devices in our everyday life

like Washing Machine, Microwave Ovens, where they are embedded in.

1.2 CHARACTERISTICS OF EMBEDDED SYSTEMS

An embedded system is any computer system hidden inside a product other than

a computer.

They will encounter a number of difficulties when writing embedded system

software in addition to those we encounter when we write applications.

Throughput – Our system may need to handle a lot of data in a short period of

time.

Response–Our system may need to react to events quickly.

Testability–Setting up equipment to test embedded software can be difficult.

Debug ability–Without a screen or a keyboard, finding out what the software is

doing wrong (other than not working) is a troublesome problem.

Reliability – embedded systems must be able to handle any situation without

human intervention.


SVES 2 ECE Dept.

Memory space – Memory is limited on embedded systems, and you must make

the software and the data fit into whatever memory exists.

Program installation – you will need special tools to get your software into

embedded systems.

Power consumption – Portable systems must run on battery power, and the

software in these systems must conserve power.

Processor hogs – computing that requires large amounts of CPU time can

complicate the response problem.

Cost – Reducing the cost of the hardware is a concern in many embedded system

projects; software often operates on hardware that is barely adequate for the job.

Embedded systems have a microprocessor/ microcontroller and a memory.

Some have a serial port or a network connection. They usually do not have

keyboards, screens or disk drives.

1.3 APPLICATIONS

Military and aerospace embedded software applications.

Communication applications.

Industrial automation and process control software.

Mastering the complexity of applications.

Reduction of product design time.

Real time processing of ever increasing amounts of data.

Intelligent, autonomous sensors.

1.4 CLASSIFICATION

Real Time Systems.

RTS is one which has to respond to events within a specified deadline.

A right answer after the dead line is a wrong answer.


SVES 3 ECE Dept.

1.4.1 RTS CLASSIFICATION

Hard Real Time Systems.

Soft Real Time System.

1.4.1.1 HARD REAL TIME SYSTEM

"Hard" real-time systems have very narrow response time.

Example: Nuclear power system, Cardiac pacemaker.

1.4.1.2 SOFT REAL TIME SYSTEM

"Soft" real-time systems have reduced constrains on "lateness" but still must

operate very quickly and repeatable.

Example: Railway reservation system – takes a few extra seconds the data

remains valid.


SVES 4 ECE Dept.

CHAPTER-2

GSM BASED LED SCROLLING DISPLAY BOARD

AIM

The main aim of this project is to implement wireless data communication on

LED board using GSM.

ABSTRACT

Scrolling display board is a common sight today. Advertisement is going digital.

The use of led scrolling display board at big shops, shopping centers, railway station,

bus stands and educational Institutes are becoming an effective mode of communication

in providing information to the people. But these off-the-shelf units are somewhat

inflexible in terms of updating the message instantly. If the user wants to change the

message it needs to be done using a computer and hence the person needs to be Present

at the location of the display board. It means the message cannot be changed from

wherever or whenever. Also the display board cannot be placed anywhere because of

complex and delicate wiring.

GSM based LED Scrolling Display Board’ is a model for displaying

notices/messages at places that require real-time noticing, by sending messages in the

form of SMS through mobile. The project aims to develop a moving sign board which

empowers the user to change the scrolling message using SMS service instantaneously

unlike a deskbound device such as PC or laptop. The user can update it even from a

remote distant. The SMS is deleted from the SIM each time it is read, thus making room

for the next SMS.


SVES 5 ECE Dept.

BLOCK DIAGRAM

Figure 2: Block diagram of E-notice board

DESCRIPTION

The system required for this purpose is nothing but, a Microcontroller based

SMS box. The main components of the kit includes Microcontroller, GSM modem.

These components are integrated with the display board and thus incorporate the

wireless features. The GSM modem receives the SMS. The AT commands are serially

transferred to the modem through MAX232. In return the modem transmits the stored

message through the COM port. The microcontroller validates the SMS and then

displays the message in the LED display board. Various time division multiplexing

techniques have been suggested to make the display boards function efficiently. The

microcontroller used in this case is AT89s52, Motorola C168 is used as the GSM

modem. In this prototype model, LED display is used for simulation purpose. During

the process of implementation this can be replaced by actual display boards. In addition

to address matching, data can be received only by the dedicated receiver, and this data

is displayed on LED. It displays the same message untill its receives another verified

message.


SVES 6 ECE Dept.

ALGORITHM

1. When a valid mobile user sends the SMS to GSM module, he gets an

acknowledgement.

2. The GSM processor receives the message, verifies it and transfers to the

microcontroller.

3. Microcontroller processes the message and sends it to the LED Display Board.

4. LED Display Board displays the previous message untill a new verified message is

received.


SVES 7 ECE Dept.

CHAPTER-3

HARDWARE REQUIREMENTS

HARDWARE COMPONENTS:

POWER SUPPLY

MICROCONTROLLER (LPC2148)

GSM

MAX232

LED BOARD

3.1 POWER SUPPLY

3.1.1 TRANSFORMER

Transformers convert AC electricity from one voltage to another with a little

loss of power. Step-up transformers increase voltage, step-down transformers reduce

voltage. Most power supplies use a step-down transformer to reduce the dangerously

high voltage to a safer low voltage.

Fig 3.1.1: A typical transformer

The input coil is called the primary and the output coil is called the secondary.

There is no electrical connection between the two coils; instead they are linked by an

alternating magnetic field created in the soft-iron core of the transformer. The two lines

in the middle of the circuit symbol represent the core. Transformers waste very little

power so the power out is (almost) equal to the power in. Note that as voltage is stepped

down and current is stepped up.


SVES 8 ECE Dept.

The ratio of the number of turns on each coil, called the turn’s ratio, determines

the ratio of the voltages. A step-down transformer has a large number of turns on its

primary(input) coil which is connected to the high voltage mains supply, and a small

number of turns on its secondary (output) coil to give a low output voltage.

TURNS RATIO = (Vp / Vs) = (Np / Ns)

Where,

Vp = primary (input) voltage.

Vs = secondary (output) voltage

Np = number of turns on primary coil

Ns = number of turns on secondary coil

Ip = primary (input) current

Is = secondary (output) current.

3.1.2 IDEAL POWER EQUATION

Figure 3.1.2: Ideal power equation

The ideal transformer as a circuit element

If the secondary coil is attached to a load that allows current to flow, electrical

power is transmitted from the primary circuit to the secondary circuit. Ideally, the

transformer is perfectly efficient; all the incoming energy is transformed from the

primary circuit to the magnetic field and into the secondary circuit. If this condition is

met, the incoming electric power must equal the outgoing power:

Giving the ideal transformer equation

http://en.wikipedia.org/wiki/Magnetic_field

http://en.wikipedia.org/wiki/Electric_power


SVES 9 ECE Dept.

Transformers normally have high efficiency, so this formula is a reasonable

approximation.

If the voltage is increased, then the current is decreased by the same factor. The

impedance in one circuit is transformed by the square of the turn’s ratio. For example,

if an impedance Zs is attached across the terminals of the secondary coil, it appears to

the primary circuit to have an impedance of (Np/Ns)2Zs. This relationship is reciprocal,

so that the impedance Zp of the primary circuit appears to the secondary to be (Ns/Np)2Zp.

3.1.3 VOLTAGE REGULATOR 7805

FEATURES

Output Current up to 1A.

Output Voltages of 5.

Thermal Overload Protection.

Short Circuit Protection.

Output Transistor Safe Operating Area Protection.

Fig 3.1.3: Circuit diagram of voltage regulator


SVES 10 ECE Dept.

DESCRIPTION

The LM78XX/LM78XXA series of three-terminal positive regulators are

available in the TO-220/D-PAK package and with several fixed output voltages,

making them useful in a Wide range of applications. Each type employs internal current

limiting, thermal shutdown and safe operating area protection, making it essentially

indestructible. If adequate heat sinking is provided, they can deliver over 1A output

Current. Although designed primarily as fixed voltage regulators, these devices can be

used with external components to obtain adjustable voltages and currents.

3.1.3.1 INTERNAL BLOCK DIAGRAM

Fig 3.1.3.1: Block diagram of voltage regulator

3.1.3.3 ABSOLUTE MAXIMUM RATINGS

Table 3.1.3.2: Rating of the voltage regulator


SVES 11 ECE Dept.

3.1.4 RECTIFIER

A rectifier is an electrical device that converts AC, which periodically reverses

direction to DC current that flows in only one direction, a process known as

rectification. Rectifiers have many uses including as components of power supplies and

as detectors of radio signals. Rectifiers may be made of solid state diodes, vacuum tube

diodes, mercury arc valves, and other components. The output from the transformer is

fed to the rectifier. It converts A.C. into pulsating D.C. The rectifier may be a half wave

or a full wave rectifier. In this project, a bridge rectifier is used because of its merits

like good stability and full wave rectification. In positive half cycle only two diodes( 1

set of parallel diodes) will conduct, in negative half cycle remaining two diodes will

conduct and they will conduct only in forward bias only.

Figure 3.1.4: Bridge rectifier

3.1.5 FILTER

Capacitive filter is used in this project. It removes the ripples from the output of

rectifier and smoothens the D.C. Output received from this filter is constant until the

mains voltage and load is maintained constant. However, if either of the two is varied,

D.C. voltage received at this point changes. Therefore a regulator is applied at the

output stage.

The simple capacitor filter is the most basic type of power supply filter. The use

of this filter is very limited. It is sometimes used on extremely high-voltage, low-current

power supplies for cathode-ray and similar electron tubes that require very little load

current from the supply. This filter is also used in circuits where the power-supply ripple

http://en.wikipedia.org/wiki/Power_supply

http://en.wikipedia.org/wiki/Detector_(radio)

http://en.wikipedia.org/wiki/Radio

http://en.wikipedia.org/wiki/Solid_state_(electronics)

http://en.wikipedia.org/wiki/Diode

http://en.wikipedia.org/wiki/Vacuum_tube

http://en.wikipedia.org/wiki/Mercury_arc_valve


SVES 12 ECE Dept.

frequency is not critical and can be relatively high. Below figure can show how the

capacitor charges and discharges.

Fig 3.1.6: Filter output

3.2 INTRODUCTION TO LPC2148 MICROCONTROLLER

3.2.1 INTRODUCTION

The LPC2141/2/4/6/8 microcontrollers are based on a 32/16 bit ARM7TDMI-

S CPU with real-time emulation and embedded trace support, that combines the

microcontroller with embedded high speed flash memory ranging from 32 kB to 512

kB. A 128-bit wide memory interface and a unique accelerator architecture enable

32-bit code execution at the maximum clock rate. For critical code size applications,

the alternative 16-bit Thumb mode reduces code by more than 30 % with minimal

performance penalty. Due to their tiny size and low power consumption,

LPC2141/2/4/6/8 are ideal for applications where miniaturization is a key

requirement, such as access control and point-of-sale. A blend of serial

communications interfaces ranging from a USB 2.0 Full Speed device, multiple

UARTs, SPI, SSP to I2Cs, and on-chip SRAM of 8 kB up to 40 kB, make these

devices very well suited for communication gateways and protocol converters, soft

modems, voice recognition and low end imaging, providing both large buffer size and

high processing power. Various 32-bit timers, single or dual 10-bit ADC(s), 10-bit


SVES 13 ECE Dept.

DAC, PWM channels and 45 fast GPIO lines with up to nine edge or level sensitive

external interrupt pins make these microcontrollers particularly suitable for industrial

control and medical systems.

3.2.2 FEATURES

16/32-bit ARM7TDMI-S microcontroller in a tiny LQFP64 package.

8 to 40 kB of on-chip static RAM and 32 to 512 kB of on-chip flash program

memory. 128 bit wide interface/accelerator enables high speed 60 MHz

operation.

In-System/In-Application Programming via on-chip boot-loader software.

o Single flash sector or full chip erase in 400 ms and programming of 256

bytes in 1ms.

Embedded ICE RT and Embedded Trace interfaces offer real-time debugging

with the on-chip Real Monitor software and high speed tracing of instruction

execution.

USB 2.0 Full Speed compliant Device Controller with 2 kB of endpoint RAM.

o In addition, the LPC2146/8 provide 8 kB of on-chip RAM accessible to

USB by DMA.

One or two (LPC2141/2 vs. LPC2144/6/8) 10-bit A/D converters provide a total

of 6/14 analog inputs, with puts, with conversion times as low as 2.44 µs per

channel.

One or two (LPC2141/2 vs. LPC2144/6/8) 10-bit A/D converters provide a total

of 6/14 analog inputs, with conversion times as low as 2.44 µs per channel.

Single 10-bit D/A converter provides variable analog output.

Two 32-bit timers/external event counters (with four capture and four

compare channels each), PWM unit (six outputs) and watchdog.

Low power real-time clock with independent power and dedicated 32 kHz clock

input.

Multiple serial interfaces including two UARTs (16C550), two Fast I2C-bus

o (400 kbit/s), SPI and SSP with buffering and variable data length

capabilities.

Vectored interrupt controller with configurable priorities and vector addresses.


SVES 14 ECE Dept.

Up to 45 of 5 V tolerant fast general purpose I/O pins in a tiny LQFP64 package.

Up to nine edge or level sensitive external interrupt pins available.

60 MHz maximum CPU clock available from programmable on-chip PLL

with settling time of 100 µs.

On-chip integrated oscillator operates with an external crystal in range from 1

MHz to

o 30 MHz and with an external oscillator up to 50 MHz.

Power saving modes include Idle and Power-down.

Individual enable/disable of peripheral functions as well as peripheral clock

scaling for additional power optimization.

Processor wake-up from Power-down mode via external interrupt, USB, BOD

or RTC

Single power supply chip with POR and BOD circuits:

3.2.3 APPLICATIONS

Industrial control

Medical systems

Access control

Point-of-sale

Communication gateway

Embedded soft modem

General purpose applications

3.2.4 ARCHITECTURAL OVERVIEW

The LPC2141/2/4/6/8 consists of an ARM7TDMI-S CPU with emulation

support, the ARM7 Local Bus for interface to on-chip memory controllers, the

AMBA Advanced High-performance Bus for interface to the interrupt controller, and

the ARM Peripheral Bus (APB, a compatible superset of ARM’s AMBA Advanced

Peripheral Bus) for connection to on-chip peripheral functions. The LPC2141/24/6/8

configures the ARM7TDMI-S processor in little-endian byte order.AHB peripherals

are allocated a 2 megabyte range of addresses at the very top of the4 giga byt e ARM

memory space. Each AHB peripheral is allocated a 16 kB address space within the


SVES 15 ECE Dept.

AHB address space. LPC2141/2/4/6/8 peripheral functions (other than the interrupt

controller) are connected to the APB bus. The AHB to APB bridge interfaces the APB

bus to the AHB bus. APB peripherals are also allocated a 2 megabyte range of

addresses, beginning at the 3.5 gigabyte address point. Each APB peripheral is

allocated a 16 kB address space within the APB address space.

3.2.5 ARM7TDMI-S PROCESSOR

The ARM7TDMI-S is a general purpose 32-bit microprocessor, which offers

high performance and very low power consumption. The ARM architecture is based

on RISC principles, and the instruction set and related decode mechanism are much

simpler than those of micro programmed CISC. This simplicity results in a high

instruction throughput and impressive real-time interrupt response from a small and

cost-effective processor core. Pipeline techniques are employed so that all parts of the

processing and memory systems can operate continuously. Typically, while one

instruction is being executed, its successor is being decoded, and a third instruction

is being fetched from memory. The ARM7TDMI-S processor also employs a unique

architectural strategy known as THUMB, which makes it ideally suited to high-

volume applications with memory restrictions, or applications where code density is

an issue. The key idea behind THUMB is that of a super-reduced instruction set.

Essentially, the

ARM7TDMI-S processor has two instruction sets:

The standard 32-bit ARM instruction set.

A 16-bit THUMB instruction set.

The THUMB set’s 16-bit instruction length allows it to approach twice the

density of standard ARM code while retaining most of the ARM’s performance

advantage over a traditional 16-bit processor using 16-bit registers. This is possible

because THUMB code operates on the same 32-bit register set as ARM code.

THUMB code is able to provide up to 65% of the code size of ARM, and 160% of the

performance of an equivalent ARM processor connected to a 16-bit memory system.

3.2.5.1 ON-CHIP FLASH MEMORY SYSTEM

The LPC2141/2/4/6/8 incorporates a 32 kB, 64 kB, 128 kB, 256 kB, and 512

kB Flash memory system, respectively. This memory may be used for both code and


SVES 16 ECE Dept.

data storage. Programming of the Flash memory may be accomplished in several

ways: over the serial built-in JTAG interface, using ISP and UART0, or by means of

IAP capabilities. The application program, using the IAP functions, may also erase

and/or program the Flash while the application is running, allowing a great degree of

flexibility for data storage field firmware upgrades, etc. When the LPC2141/2/4/6/8

on-chip bootloader is used, 32 kB, 64 kB, 128 kB, 256 kB, and 500 kB of Flash

memory is available for user code. The LPC2141/2/4/6/8 Flash memory provides

minimum of 100,000 erase/write cycles and 20 years of data-retention.

3.2.5.2 ON-CHIP STATIC RAM

On-chip SRAM may be used for code and/or data storage. The on-chip SRAM

may be accessed as 8-bits, 16-bits, and 32-bits. The LPC2141/2/4/6/8 provide

8/16/32 kB of static RAM, respectively.

The LPC2141/2/4/6/8 SRAM is designed to be accessed as a byte-addressed

memory. Word and halfword accesses to the memory ignore the alignment of the

address and access the naturally-aligned value that is addressed (so a memory access

ignores address bits 0 and 1 for word accesses, and ignores bit 0 for halfword

accesses). Therefore valid reads and writes require data accessed as halfwords to

originate from addresses with address line 0 being 0 (addresses ending with 0, 2, 4, 6,

8, A, C, and E in hexadecimal notation) and data accessed as words to originate from

addresses with address lines 0 and 1 being 0 (addresses ending with 0, 4, 8, and C in

hexadecimal notation). This rule applies to both off and on-chip memory usage.

The SRAM controller incorporates a write-back buffer in order to prevent CPU

stalls during back-to-back writes. The write-back buffer always holds the last data sent

by software to the SRAM. This data is only written to the SRAM when another write

is requested by software. If a chip reset occurs, actual SRAM contents will not reflect

the most recent write request. Any software that checks SRAM contents after reset

must take this into account. Two identical writes to a location guarantee that the data

will be present after a Reset. Alternatively, a dummy write operation before entering

idle or power-down mode will similarly guarantee that the last data written will be

present in SRAM after a subsequent Reset.


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3.2.6 BLOCK DIAGRAM

Figure 3.2.6: Block diagram of micro controller


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1. Pins shared with GPIO.

2. LPC2148 only.

3. USB DMA controller with 8 kB of RAM accessible as general purpose RAM and/or

DMA is available in LPC2148 only.

3.2.6.1 MEMORY MAPS

The LPC2141/2/4/6/8 incorporates several distinct memory regions, shown in

the following figures. Figure3.2.6.1 shows the overall map of the entire address space

from the user program viewpoint following reset.

Figure 3.2.6.1 System memory map


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3.2.6.2: Peripheral memory map

Figures 3.2.6.2 through 4 and Table 2 show different views of the peripheral

address space. Both the AHB and APB peripheral areas are 2 megabyte spaces which

are divided up into 128 peripherals. Each peripheral space is 16 kilobytes in size. This

allows simplifying the address decoding for each peripheral. All peripheral register

addresses are word aligned (to 32-bit boundaries) regardless of their size. This

eliminates the need for byte lane mapping hardware that would be required to allow

byte (8-bit) or half-word (16-bit).accesses to occur at smaller boundaries. An

implication of this is that word and half-word registers must be accessed all at once.

For example, it is not possible to read or write the upper byte of a word register

separately.


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3.2.7 GENERAL PURPOSE INPUT OUTPUT PORTS

3.2.7.1 FEATURES

Every physical GPIO port is accessible via either the group of registers

providing an

enhanced features and accelerated port access or the legacy group of

register.ccelerated GPIO functions:

GPIO registers are relocated to the ARM local bus so that the fastest possible

I/O

timing can be achieved.

Mask registers allow treating sets of port bits as a group,leaving other

bits unchanged.

All registers are byte and half-word addressable.

Entire port value can be written in one instruction.

Bit-level set and clear registers allow a single instruction set or clear of any

number of bits in

one port.

Direction control of individual bits.

All I/O default to inputs after reset..

Backward compatibility with other earlier devices is maintained with legacy

registers

appearing at the original addresses on the APB bus.

3.2.7.2 APPLICATIONS

General purpose I/O

Driving LEDs, or other indicators

Controlling off-chip devices

Sensing digital inputs


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3.2.8 LPC2148 PIN CONNECT BLOCK

3.2.8.1 FEATURES

Allows individual pin configuration.

3.2.8.2 APPLICATIONS

The purpose of the Pin connect block is to configure the microcontroller

pins to the desired functions.

3.2.8.3 DESCRIPTION

The pin connect block allows selected pins of the microcontroller to have more

than one function. Configuration registers control the multiplexers to allow connection

between the pin and the on chip peripherals. Peripherals should be connected to the

appropriate pins prior to being activated, and prior to any related interrupt(s) being

enabled. Activity of any enabled peripheral function that is not mapped to a related pin

should be considered undefined. Selection of a single function on a port pin

completely excludes all other functions otherwise available on the same pin. The only

partial exception from the above rule of exclusion is the case of inputs to the A/D

converter. Regardless of the function that is selected for the port pin that also hosts the

A/D input, this A/D input can be read at any time and variations of the voltage level on

this pin will be reflected in the A/D readings. However, valid analog reading(s) can be

obtained if and only if the function of an analog input is selected. Only in this case

proper interface circuit is active in between the physical pin and the A/D module. In

all other cases, a part of digital logic necessary for the digital function to be performed

will be active, and will disrupt proper behavior of the A/D.


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3.2.8.4 REGISTER DESCRIPTION

The Pin Control Module contains 2 registers as shown in table below.

Name Description Access Reset value Address

PINSEL0 Pin function select

register 0.

Read/Write 0x0000 0000 0xE002 C000

PINSEL1 Pin function select

register 1.

Read/Write 0x0000 0000 0xE002 C004

PINSEL2 Pin function select Read/Write 0xE002 C014

register 2.

Figure3.2.8.3 Pin connect block register map

3.2.8.5 LPC2148 pinout

Figure 3.2.8.5: LPC2148


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3.3 GSM TECHNOLOGY

Figure 3.3: GSM

3.3.1 Time-Division Multiple Access

1. What is TDMA?

Time division multiple access is a technology used in digital cellular telephone

communication to divide each cellular channel into three time slots in order to increase

the amount of data that can be carried.

2. How it Works?

TDMA works by time-division multiplexing: sending multiple signals (each of

which has its own time slot) simultaneously on a single carrier in the form of a complex

signal, and then recovering the separate signals at the receiving end. For TDMA, the

carrier is divided into three time slots, each of which serves one subscriber. The

information is broken into tiny data packets, which are transmitted in timed bursts in

the 30-megahertz range. At the receiving end, the separate information streams are

recovered. See also FDMA and CDMA TDMA was developed in response to the

basic wireless network problem:

large numbers of users and limited frequency allotments. TDMA increases

network efficiency by enabling single connections to carry multiple data channels,

offering a three-fold increase in capacity over AMPS networks. Flexible and scalable,

TDMA facilitates step-by-step migration to digital operation. TDMA can be

implemented seamlessly across both 800- and 1900-MHz networks. Its hierarchical cell

structure allows service providers to increase capacity where demand is greatest, in

high-use areas. TDMA is applied in Digital-American Mobile Phone Service, Global


SVES 24 ECE Dept.

System for Mobile communications, and PDC. However, each of these systems

implements TDMA in a somewhat different and incompatible way. TDMA was first

specified as a standard in EIA/TIA Interim Standard 54 (IS-54). IS-136, an evolved

version of IS-54, is the United States standard for TDMA for both the cellular (850

MHz) and personal communications services (1.9 GHz) spectrums. TDMA is also used

for Digital Enhanced Cordless Telecommunications.

CDMA

The term CDMA refers to any of several protocols used in so-called 2G and

3G wireless communications. As the term implies, CDMA is a form of multiplexing,

which allows numerous signals to occupy a single transmission channel, optimizing the

use of available bandwidth. The technology is used in UHF cellular telephone systems

in the 800-MHz and 1.9-GHz bands. CDMA employs ADC in combination with spread

spectrum technology. Audio input is first digitized into binary elements. The frequency

of the transmitted signal is then made to vary according to a defined pattern (code), so

it can be intercepted only by a receiver whose frequency response is programmed with

the same code, so it follows exactly along with the transmitter frequency. There are

trillions of possible frequency-sequencing codes; this enhances privacy and makes

cloning difficult.

The CDMA channel is nominally 1.23 MHz wide. CDMA networks use a

scheme called soft handoff, which minimizes signal breakup as a handset passes from

one cell to another. The combination of digital and spread-spectrum modes supports

several times as many signals per unit bandwidth as analog modes. CDMA is

compatible with other cellular technologies; this allows for nationwide roaming. The

original CDMA standard, also known as CDMA One and still common in cellular

telephones in the U.S., offers a transmission speed of only up to 14.4 Kbps in its single

channel form and up to 115 Kbps in an eight-channel form. CDMA2000 and wideband

CDMA deliver data many times faster.

3.3.2 GLOBAL SYSTEM FOR MOBILE COMMUNICATION

1. What is GSM?

The Global System for Mobile communication, usually called GSM, (ETSI) to

describe protocols for 2G digital cellular networks used by mobile phones. The GSM

standard was developed as a replacement for 1G analog cellular networks, and


SVES 25 ECE Dept.

originally described a digital, circuit switched network optimized for full duplex voice

telephony. This was expanded over time to include data communications, first by circuit

switched transport, then packet data transport via GPRS and EDGE. Further

improvements were made when the 3GPP developed 3G UMTS standards followed by

4G LTE Advanced standards. "GSM" is a trademark owned by the GSM Association.

GSM is a cellular network, which means that mobile phones connect to it by

searching for cells in the immediate vicinity.

Figure 3.3.2: Global system for mobile communication (GSM)

The ubiquity of the GSM standard makes international roaming very common

between mobile phone operators, enabling subscribers to use their phones in many parts

of the world. GSM differs significantly from its predecessors in that both signalling and

speech channels are Digital call quality, which means that it is considered a 2G mobile

phone system. This fact has also meant that data communication was built into the

system from the 3rd Generation Partnership Project 3GPP.

GSM is a digital mobile telephone system that is widely used in Europe and

other parts of the world. GSM uses a variation of time division multiple access (Time

Division Multiple Access) and is the most widely used of the three digital wireless

telephone technologies GSM digitizes and compresses data, then sends it down a

channel with two other streams of user data, each in its own time slot. It operates at

either the 900 MHz or 1800 MHz frequency band.

GSM is the de facto wireless telephone standard in Europe. GSM has over 120

million users worldwide and is available in 120 countries, according to the GSM MOU


SVES 26 ECE Dept.

Association. Since many GSM network operators have roaming agreements with

foreign operators, users can often continue to use their mobile phones when they travel

to other countries.

American Personal Communications a subsidiary of Sprint, is using GSM as the

technology for a broadband personal communications service (personal

communications services). The service will ultimately have more than 400 base stations

for the palm-sized handsets that are being made by Ericsson, Motorola, and Nokia. The

handsets include a phone, a text pager, and an answering machine.

GSM together with other technologies is part of an evolution of wireless mobile

telecommunication that includes High-Speed Circuit-Switched Data (High-Speed

Circuit-Switched Data), General Packet Radio System (General Packet Radio

Services), Enhanced Data GSM Environment (Enhanced Data GSM Environment), and

Universal Mobile Telecommunications Service (Universal Mobile

Telecommunications System).

3.3.3 THE GENERATIONS OF MOBILE NETWORKS

The idea of cell-based mobile radio systems appeared at Bell Laboratories in

the United States in the early 1970s. However, mobile cellular systems were not

introduced for commercial use until a decade later. During the early 1980’s, analog

cellular telephone systems experienced very rapid growth in Europe, particularly in

Scandinavia and the United Kingdom. Today, cellular systems still represent one of

the fastest growing telecommunications systems. During development, numerous

problems arose as each country developed its own system, producing equipment limited

to operate only within the boundaries of respective countries, thus limiting the markets

in which services could be sold.

First-generation cellular networks, the primary focus of the communications

industry in the early 1980’s, were characterized by a few compatible systems that were

designed to provide purely local cellular solutions. It became increasingly apparent that

there would be an escalating demand for a technology that could facilitate flexible and

reliable mobile communications. By the early 1990’s, the lack of capacity of these

existing networks emerged as a core challenge to keeping up with market demand. The

first mobile wireless phones utilized analog transmission technologies, the dominant

analog standard being known as “AMPS”. Analog standards operated on bands of


SVES 27 ECE Dept.

spectrum with a lower frequency and greater wavelength than subsequent standards,

providing a significant signal range per cell along with a high propensity for

interference. Nonetheless, it is worth noting the continuing persistence of analog

AMPS technologies in North America and Latin America through the 1990’s.

Initial deployments of second-generation wireless networks occurred in Europe

in the 1980’s. These networks were based on digital, rather than analog technologies,

and were circuit-switched. Circuit-switched cellular data is still the most widely used

mobile wireless data service. Digital technology offered an appealing combination of

performance and spectral efficiency (in terms of management of scarce frequency

bands), as well as the development of features like speech security and data

communications over high quality transmissions. It is also compatible with Integrated

Services Digital Network ISDN technology, which was being developed for land-based

telecommunication systems throughout the world, and which would be necessary for

GSM to be successful. Moreover in the digital world, it would be possible to employ

very large-scale integrated silicon technology to make handsets more affordable.

To a certain extent, the late 1980’s and early 1990’s were characterized by the

perception that a complete migration to digital cellular would take many years, and that

digital systems would suffer from a number of technical difficulties (i.e., handset

technology). However, second-generation equipment has since proven to offer many

advantages over analog systems, including efficient use of radio-magnetic spectrum,

enhanced security, extended battery life, and data transmission capabilities. There are

four main standards for 2G networks: TDMA, GSM and CDMA; there is also PDC,

which is used exclusively in Japan. In the meantime, a variety of 2.5G standards (to

be discussed in Section 2.7) have been developed. ‘Going digital’ has led to the

emergence of several major 2G mobile wireless systems.

3.3.4 HISTORY OF GSM

Early European analog cellular networks consisted of a mix of technologies and

protocols that varied from country to country, meaning that phones did not necessarily

work on different networks. In addition, manufacturers had to produce different

equipment to meet various standards across the markets.

In 1982, work began to develop a European standard for digital cellular voice

telephony when the European Conference of Postal and Telecommunications


SVES 28 ECE Dept.

Administrations created the Groupe Spécial Mobile committee and provided a

permanent group of technical support personnel, based in Paris. Five years later in 1987,

15 representatives from 13 European countries signed a memorandum of understanding

in Copenhagen to develop and deploy a common cellular telephone system across

Europe, and European Union rules were passed to make GSM a mandatory standard.

The decision to develop a continental standard eventually resulted in a unified, open,

standard-based network which was larger than that in the United States. In 1989, the

Groupe Spécial Mobile committee was transferred from to the European

Telecommunications Standards Institute

In parallel, France and Germany signed a joint development agreement in 1984

and were joined by Italy and the UK in 1986. In 1986 the European Commission

proposed reserving the 900 MHz spectrum band for GSM.

Phase I of the GSM specifications were published in 1990. The world's first

GSM call was made by the Finnish prime minister Harri Holkeri to Kaarina Suonio

(mayor in city ofTampere) on 1 July 1991 on a network built by Telenokia and Siemens

and operated by Radiolinja. The following year in 1992, the first short messaging

service (SMS or "text message") message was sent and Vodafone UK and Telecom

Finland signed the first international roaming agreement.

Work begun in 1991 to expand the GSM standard to the 1800 MHz frequency

band and the first 1800 MHz network became operational in the UK by 1993. Also that

year, Telecom Australia became the first network operator to deploy a GSM network

outside Europe and the first practical hand-held GSM mobile phone became available.

In 1995, fax, data and SMS messaging services were launched commercially,

the first 1900 MHz GSM network became operational in the United States and GSM

subscribers worldwide exceeded 10 million. Also this year, the GSM Association was

formed. Pre-paid GSM SIM cards were launched in 1996 and worldwide GSM

subscribers passed 100 million in 1998.

In 2000, the first commercial GPRS services were launched and the first GPRS

compatible handsets became available for sale. In 2001 the first UMTS (W-CDMA)

network was launched and worldwide GSM subscribers exceeded 500 million. In 2002

the first multimedia messaging services were introduced and the first GSM network in

the 800 MHz frequency band became operational. EDGE services first became

operational in a network in 2003 and the number of worldwide GSM subscribers

exceeded 1 billion in 2004.


SVES 29 ECE Dept.

By 2005, GSM networks accounted for more than 75% of the worldwide

cellular network market, serving 1.5 billion subscribers. In 2005, the first HSDPA

capable network also became operational. The first HSUPA network was launched in

2007 and worldwide GSM subscribers exceeded two billion in 2008.

The GSM Association estimates that technologies defined in the GSM standard

serve 80% of the global mobile market, encompassing more than 5 billion people across

more than 212 countries and territories, making GSM the most ubiquitous of the many

standards for cellular networks.

Macau phased out their GSM network in January 2013 (except for roaming

services), making it the first region to decommission a GSM network.

3.3.4.1 ARCHITECTURE OF THE GSM NETWORK

A GSM network is composed of several functional entities, whose functions

and interfaces are specified. Figure 3.3.4.1 shows the layout of a generic GSM network.

The GSM network can be divided into three broad parts. The Mobile Station is carried

by the subscriber. The Base Station Subsystem controls the radio link with the Mobile

Station. The Network Subsystem, the main part of which is the Mobile services

Switching Center, performs the switching of calls between the mobile users, and

between mobile and fixed network users. The MSC also handles the mobility

management operations. The Mobile Station and the Base Station Subsystem

communicate across the Um interface, also known as the air interface or radio link. The

Base Station Subsystem communicates with the Mobile services Switching Center

across the A interface.

Figure 3.3.4.1: General architecture of a GSM network


SVES 30 ECE Dept.

3.3.4.2 MOBILE STATION

The mobile station (MS) consists of the mobile equipment (the terminal) and a

smart card called the Subscriber Identity Module. The SIM provides personal mobility,

so that the user can have access to subscribed services irrespective of a specific

terminal. By inserting the SIM card into another GSM terminal, the user is able to

receive calls at that terminal, make calls from that terminal, and receive other

subscribed services.

The mobile equipment is uniquely identified by the International Mobile

Equipment Identity (IMEI). The SIM card contains the International Mobile Subscriber

Identity used to identify the subscriber to the system, a secret key for authentication,

and other information. The IMEI and the IMSI are independent, thereby allowing

personal mobility. The SIM card may be protected against unauthorized use by a

password or personal identity number.

3.3.4.3 BASE STATION SUBSYSTEM

The Base Station Subsystem is composed of two parts, the Base Transceiver

Station and the Base Station Controller. These communicate across the standardized

Abis interface, allowing (as in the rest of the system) operation between components

made by different suppliers.

The Base Transceiver Station houses the radio transceivers that define a cell and

handles the radio-link protocols with the Mobile Station. In a large urban area, there

will potentially be a large number of BTSs deployed, thus the requirements for a BTS

are ruggedness, reliability, portability, and minimum cost.

The Base Station Controller manages the radio resources for one or more BTSs.

It handles radio-channel setup, frequency hopping, and handovers. The BSC is the

connection between the mobile station and the Mobile service Switching Center .

3.3.4.4 NETWORK SUBSYSTEM

The central component of the Network Subsystem is the Mobile services

Switching Center . It acts like a normal switching node of the PSTN or ISDN, and

additionally provides all the functionality needed to handle a mobile subscriber, such

as registration, authentication, location updating, handovers, and call routing to a

roaming subscriber. The MSC provides the connection to the fixed networks (such as

the PSTN or ISDN). Signaling between functional entities in the Network Subsystem


SVES 31 ECE Dept.

uses Signaling System Number 7, used for trunk signaling in ISDN and widely used in

current public networks.

The Home Location Register and Visitor Location Register, together with the

MSC, provide the call-routing and roaming capabilities of GSM. The HLR contains all

the administrative information of each subscriber registered in the corresponding GSM

network, along with the current location of the mobile. The location of the mobile is

typically in the form of the signaling address of the VLR associated with the mobile

station. There is logically one HLR per GSM network, although it may be implemented

as a distributed database.

The Visitor Location Register contains selected administrative information

from the HLR, necessary for call control and provision of the subscribed services, for

each mobile currently located in the geographical area controlled by the VLR. The

geographical area controlled by the MSC corresponds to that controlled by the VLR.

Note that the MSC contains no information about particular mobile stations --- this

information is stored in the location registers.

The other two registers are used for authentication and security purposes. The

Equipment Identity Register is a database that contains a list of all valid mobile

equipment on the network, where each mobile station is identified by its International

Mobile Equipment Identity . An IMEI is marked as invalid if it has been reported stolen

or is not type approved. The Authentication Center is a protected database that stores

a copy of the secret key stored in each subscriber's SIM card, which is used for

authentication and encryption over the radio channel.

3.3.4.5 GSM FREQUENCIES USING AROUND THE WORLD

In North America, GSM operates on the primary mobile communication bands

850 MHz and 1,900 MHz. In Canada, GSM-1900 is the primary band used in urban

areas with 850 as a backup, and GSM-850 being the primary rural band. In the United

States, regulatory requirements determine which area can use which band.

GSM-1900 and GSM-850 are also used in most of South and Central America,

and both Ecuador and Panama use GSM-850 exclusively (Note: Since November 2008,

a Panamanian operator has begun to offer GSM-1900 service). Venezuela and Brazil

use GSM-850 and GSM-900/1800 mixing the European and American bands. Some

countries in the Americas use GSM-900 or GSM-1800, some others use three: GSM-

850/900/1900, GSM-850/1800/1900, GSM-900/1800/1900 or GSM-850/900/1800.


SVES 32 ECE Dept.

Soon some countries will use GSM-850/900/1800/1900 MHz like the Dominican

Republic, Trinidad & Tobago and Venezuela.

In Brazil, the 1,900 MHz band is paired with 2,100 MHz to form the IMT-

compliant 2,100 MHz band for 3G services. The result is a mixture of usage in the

Americas that requires travelers to confirm that the phones they have are compatible

with the band of the networks at their destinations.Frequency compatibility problems

can be avoided through the use of multi-band (tri-band or, especially, quad-band)

phones.

3.3.4.5 GSM frequencies using around the world

In Africa, Europe, Middle East and Asia, most of the providers use 900 MHz

and 1800 MHz bands. GSM-900 is most widely used. Fewer operators use DCS-1800

and GSM-1800. A dual-band 900/1800 phone is required to be compatible with almost

all operators. At least the GSM-900 band must be supported in order to be compatible

with many operators. However, Thailand has also approved for some time now the use

of the GSM-1900 band in an attempt to alleviate network congestion.

3.3.5 GSM SECURITY

The security features in the GSM network can be divided into three sub parts:

subscriber identity authentication, user and signaling data confidentiality, and

subscriber identity confidentiality. The security mechanisms include secret keys,

algorithms and computed numbers.

3.3.5.1 SOME DEFINITIONS

Authentication – any technique that enables the receiver to automatically

identify and reject messages that have been altered deliberately or by channel

errors


SVES 33 ECE Dept.

Confidentiality – only the sender and intended receiver should be able to

understand the contents of the transmitted message.

Cipher text – plaintext is encrypted to cipher text with the help of a key and an

encryption algorithm

Key – a string of numbers or characters as input to the encryption algorithm

The base mechanism shows where the different keys and algorithms are stored.

The secret key Ki is used to authenticate the identity of a subscriber. The key Ki is

given to the subscriber when he opens a new network account. Only the network

operator knows the key. The Ki is stored in the subscribers SIM card and the AuC of

the subscribers home network. The Ki is never transmitted over the network.

Figure 3.3.4.1: Base of the security mechanism.

A3 is the algorithm used to authenticate the subscriber. Data transmitted

between the MS and the BTS is encrypted by the A5 algorithm. The A8 algorithm

generates the needed ciphering key Kc used by A5. Subscriber Identity Authentication.

The procedure consists of three phases,

1. the network must identify the subscriber,

2. needed security parameters from the home network are asked for and

3. the actual authentication is taking place.


SVES 34 ECE Dept.

Figure3.3.4.2 Subscriber identification process.

In order to identify the subscriber the MS sends the IMSI to the visited network.

With the IMSI the subscriber is identified to the system. The IMSI is up to 15 digits

and comprises the following parts:

A 3-digit Mobile Country Code. This identifies the country where the GSM

system operates. Finland has number 244.

A 2-digit Mobile Network Code. This uniquely identifies each cellular provider.

Sonera has number 91.

The Mobile Subscriber Identification Code. This uniquely identifies each

customer of the provider. The length is 10 digits.

So called security triplets are calculated in the AuC. The triplets consist of a

random number, a signed response and a ciphering key. The SRES is used to

authenticate the subscriber and Kc is used as input by the ciphering algorithm A5

Figure 3.3.4.3. Calculating the security triplets.


SVES 35 ECE Dept.

As the visited network has received the security triplets the actual authentication

can take place (see Figure 3.3.4.4). If the number sent by the MS to the BTS is the same

as the one calculated by the AuC, the subscriber is authenticated.

Figure 3.3.4.4: Authentication the subscriber

3.3.5.2 USER AND SIGNALING DATA CONFIDENTIALITY

The Ciphering key is used for the final encryption of the radio link. One copy

of the needed Kc is stored in the VLR and another copy is calculated in the MS by the

A8 algorithm. The same Ki and RAND numbers are used as in the authentication

process. The A5 algorithm creates 114-bit sequence. This sequence is then XORed with

every 114 user data bits and the resulting bit streams are sent over the two 57 bit parts

of every GSM slot. All traffic between the MS and the BTS is then secured.

3.3.5.3 SUBSCRIBER IDENTITY CONFIDENTIALITY

The IMSI is the primary key for subscriber identification. However a temporary

identity, TMSI can be given to a subscriber for identification. After initial registration

done with the IMSI, the serving network stores the IMSI in the VLR and generates a

TMSI for the subscriber. The TMSI is then transmitted back to the MS and it will be

used for identification as long as the subscriber is registered in that specific network.


SVES 36 ECE Dept.

3.3.5.4 SOLUTIONS TO CURRENT SECURITY ISSUES

A corrected version of the COMP 128 has been developed; however, the cost to

replace all SIM chips and include the new algorithm is too costly to cellular phone

companies. The new release of 3GSM will include a stronger version of the COMP

128 algorithm and a new A5 algorithm implementation. The A5/3 is expected to solve

current confidentiality and integrity problems. Fixed network transmission could be

fixed by simply applying some type of encryption to any data transferred on the fixed

network.

3.3.5.5 SHORT MESSAGE SERVICE (SMS)

Short Message Service (more commonly known as text messaging) has become

the most used data application on mobile phones, with 74% of all mobile phone users

worldwide already as active users of SMS, or 2.4 billion people by the end of 2007.

SMS text messages may be sent by mobile phone users to other mobile users or external

services that accept SMS. The messages are usually sent from mobile devices via

theShort Message Service Centre using the MAP protocol. The SMSC is a central

routing hubs for Short Messages. Many mobile service operators use their SMSCs as

gateways to external systems, including the Internet, incoming SMS news feeds, and

other mobile operators (often using the de facto SMPP standard for SMS exchange).

3.4 MAX232 IC

The MAX232 IC is used to convert the TTL/CMOS logic levels to RS232 logic

levels during serial communication of microcontrollers with PC. The controller

operates at TTL logic level (0-5V) whereas the serial communication in PC works on

RS232 standards (-25 V to + 25V). This makes it difficult to establish a direct link

between them to communicate with each other.

The intermediate link is provided through MAX232. It is a dual driver/receiver

that includes a capacitive voltage generator to supply RS232 voltage levels from a

single 5V supply. Each receiver converts RS232 inputs to 5V TTL/CMOS levels. These

receivers (R1 & R2) can accept ±30V inputs. The drivers (T1 & T2), also called

transmitters, convert the TTL/CMOS input level into RS232 level.

The transmitters take input from controller’s serial transmission pin and send

the output to RS232’s receiver. The receivers, on the other hand, take input from


SVES 37 ECE Dept.

transmission pin of RS232 serial port and give serial output to microcontroller’s

receiver pin. MAX232 needs four external capacitors whose value ranges from 1µF to

22µF.

Figure 3.4.0: MAX232N

Figure 3.4.1: Pin diagram of MAX232N


SVES 38 ECE Dept.

3.4.1FUNCTIONS OF PINS

Pin

No Function Name

1

Capacitor connection pins

Capacitor 1 +

2 Capacitor 3 +

3 Capacitor 1 -

4 Capacitor 2 +

5 Capacitor 2 -

6 Capacitor 4 -

7 Output pin; outputs the serially transmitted data at RS232

logic level; connected to receiver pin of PC serial port

T2 Out

8 Input pin; receives serially transmitted data at RS 232 logic

level; connected to transmitter pin of PC serial port

R2 In

9 Output pin; outputs the serially transmitted data at TTL

logic level; connected to receiver pin of controller.

R2 Out

10 Input pins; receive the serial data at TTL logic level;

connected to serial transmitter pin of controller.

T2 In

11 T1 In

12 Output pin; outputs the serially transmitted data at TTL

logic level; connected to receiver pin of controller.

R1 Out

13 Input pin; receives serially transmitted data at RS 232 logic

level; connected to transmitter pin of PC serial port

R1 In

14 Output pin; outputs the serially transmitted data at RS232

logic level; connected to receiver pin of PC serial port

T1 Out

15 Ground (0V) Ground

16 Supply voltage; 5V (4.5V – 5.5V) Vcc

Table 3.4.2 Function of pins


SVES 39 ECE Dept.

3.5 LIGHT-EMITTING DIODE

A light-emitting diode (LED) is a two-lead semiconductor light source. It is a

pn-junction diode, which emits light when activated. When a suitable voltage is applied

to the leads, electrons are able to recombine with electron holes within the device,

releasing energy in the form of photons. This effect is called electroluminescence, and

the color of the light (corresponding to the energy of the photon) is determined by the

energy band gap of the semiconductor An LED is often small in area (less than 1 mm2)

and integrated optical components may be used to shape its radiation pattern.

Appearing as practical electronic components in 1962, the earliest LEDs

emitted low-intensity infrared light. Infrared LEDs are still frequently used as

transmitting elements in remote-control circuits, such as those in remote controls for a

wide variety of consumer electronics. The first visible-light LEDs were also of low

intensity, and limited to red. Modern LEDs are available across the visible, ultraviolet,

and infrared wavelengths, with very high brightness. Early LEDs were often used as

indicator lamps for electronic devices, replacing small incandescent bulbs. They were

soon packaged into numeric readouts in the form of seven-segment displays, and were

commonly seen in digital clocks.

Recent developments in LEDs permit them to be used in environmental and task

lighting. LEDs have many advantages over incandescent light sources including lower

energy consumption, longer lifetime, improved physical robustness, smaller size, and

faster switching. Light-emitting diodes are now used in applications as diverse as

aviation lighting, automotive headlamps, advertising, general lighting, traffic signals,

and camera flashes. However, LEDs powerful enough for room lighting are still

relatively expensive, and require more precise current and heat management than

compact fluorescent lamp sources of comparable output.

LEDs have allowed new text, video displays, and sensors to be developed, while

their high switching rates are also useful in advanced communications technology.

http://en.wikipedia.org/wiki/Semiconductor

http://en.wikipedia.org/wiki/Light_source

http://en.wikipedia.org/wiki/Pn-junction

http://en.wikipedia.org/wiki/Diode

http://en.wikipedia.org/wiki/Voltage

http://en.wikipedia.org/wiki/Electrons

http://en.wikipedia.org/wiki/Electron_holes

http://en.wikipedia.org/wiki/Photon

http://en.wikipedia.org/wiki/Electroluminescence

http://en.wikipedia.org/wiki/Band_gap

http://en.wikipedia.org/wiki/Radiation_pattern

http://en.wikipedia.org/wiki/Visible_spectrum

http://en.wikipedia.org/wiki/Ultraviolet

http://en.wikipedia.org/wiki/Infrared

http://en.wikipedia.org/wiki/Seven-segment_display

http://en.wikipedia.org/wiki/Navigation_light#Aviation_navigation_lights

http://en.wikipedia.org/wiki/Navigation_light#Aviation_navigation_lights

http://en.wikipedia.org/wiki/Automotive_lighting#Light_emitting_diodes_.28LED.29

http://en.wikipedia.org/wiki/Lighting

http://en.wikipedia.org/wiki/Traffic_signal

http://en.wikipedia.org/wiki/Fluorescent_lamp


SVES 40 ECE Dept.

3.5.1 TECHNOLOGY

An LED will begin to emit light when more than 2 or 3 volts is applied to it.

Some external system must control the current through the LED to prevent destruction

by overheating.

The LED consists of a chip of semiconducting material doped with impurities

to create a p-n junction. As in other diodes, current flows easily from the p-side, or

anode, to the n-side, or cathode, but not in the reverse direction. Charge-carriers

electrons and holes flow into the junction from electrodes with different voltages. When

an electron meets a hole, it falls into a lower energy level and releases energy in the

form of a photon.

The wavelength of the light emitted, and thus its color, depends on the band gap

energy of the materials forming the p-n junction. In silicon or germanium diodes, the

electrons and holes usually recombine by a non-radiative transition, which produces no

optical emission, because these are indirect band gap materials. The materials used for

the LED have a direct band gap with energies corresponding to near-infrared, visible,

or near-ultraviolet light.

LED development began with infrared and red devices made with gallium

arsenide. Advances in materials science have enabled making devices with ever-shorter

wavelengths, emitting light in a variety of colors.LEDs are usually built on an n-type

substrate, with an electrode attached to the p-type layer deposited on its surface. P-type

substrates, while less common, occur as well. Many commercial LEDs, especially

GaN/InGaN, also use sapphire substrate.

Most materials used for LED production have very high refractive indices. This

means that much light will be reflected back into the material at the material/air surface

interface. Thus, light extraction in LEDs is an important aspect of LED production,

subject to much research and development.

LED performance is temperature dependent. Most manufacturers' published

ratings of LEDs are for an operating temperature of 25 °C (77 °F). LEDs used outdoors,

http://en.wikipedia.org/wiki/LED_circuit

http://en.wikipedia.org/wiki/Doping_%28semiconductor%29

http://en.wikipedia.org/wiki/P-n_junction

http://en.wikipedia.org/wiki/Anode

http://en.wikipedia.org/wiki/Electron

http://en.wikipedia.org/wiki/Electron_hole

http://en.wikipedia.org/wiki/Electrode

http://en.wikipedia.org/wiki/Energy_level

http://en.wikipedia.org/wiki/Energy

http://en.wikipedia.org/wiki/Photon

http://en.wikipedia.org/wiki/Wavelength

http://en.wikipedia.org/wiki/Band_gap

http://en.wikipedia.org/wiki/Silicon

http://en.wikipedia.org/wiki/Germanium

http://en.wikipedia.org/wiki/Indirect_band_gap

http://en.wikipedia.org/wiki/Direct_band_gap

http://en.wikipedia.org/wiki/Gallium_arsenide

http://en.wikipedia.org/wiki/Gallium_arsenide

http://en.wikipedia.org/wiki/Materials_science

http://en.wikipedia.org/wiki/Sapphire

http://en.wikipedia.org/wiki/Refractive_index

http://en.wikipedia.org/wiki/Light_extraction_in_LEDs

http://en.wikipedia.org/wiki/Operating_temperature


SVES 41 ECE Dept.

such as traffic signals or in-pavement signal lights, and that are utilized in climates

where the temperature within the light fixture gets very high, could result in low signal

intensities or even failure.

LED light output rises at lower temperatures, leveling off, depending on type,

at around −30 °C (−22 °F Thus, LED technology may be a good replacement in uses

such as supermarket freezer lighting and will last longer than other technologies.

Because LEDs emit less heat than incandescent bulbs, they are an energy-efficient

technology for uses such as in freezers and refrigerators. However, because they emit

little heat, ice and snow may build up on the LED light fixture in colder climates.

Similarly, this lack of waste heat generation has been observed to sometimes cause

significant problems with street traffic signals and airport runway lighting in snow-

prone areas. In response to this problem, some LED lighting systems have been

designed with an added heating circuit at the expense of reduced overall electrical

efficiency of the system; additionally, research has been done to develop heat sink

technologies that will transfer heat produced within the junction to appropriate areas of

the light fixture.

3.5.2 ADVANTAGES

Efficiency: LEDs emit more lumens per watt than incandescent light bulbs. The

efficiency of LED lighting fixtures is not affected by shape and size, unlike

fluorescent light bulbs or tubes.

Color: LEDs can emit light of an intended color without using any color filters

as traditional lighting methods need. This is more efficient and can lower initial

costs.

Size: LEDs can be very small (smaller than 2 mm2) and are easily attached to

printed circuit boards.

On/Off time: LEDs light up very quickly. A typical red indicator LED will

achieve full brightness in under a microsecond. LEDs used in communications

devices can have even faster response times.

Cycling: LEDs are ideal for uses subject to frequent on-off cycling, unlike

incandescent and fluorescent lamps that fail faster when cycled often, or High-

intensity discharge lamps (HID lamps) that require a long time before restarting.

http://en.wikipedia.org/wiki/Refrigerator#Freezer

http://en.wikipedia.org/wiki/Incandescent_light_bulb

http://en.wikipedia.org/wiki/Microsecond

http://en.wikipedia.org/wiki/High-intensity_discharge_lamp

http://en.wikipedia.org/wiki/High-intensity_discharge_lamp


SVES 42 ECE Dept.

Dimming: LEDs can very easily be dimmed either by pulse-width modulation

or lowering the forward current. This pulse-width modulation is why LED

lights, particularly headlights on cars, when viewed on camera or by some

people, appear to be flashing or flickering. This is a type of stroboscopic effect.

Cool light: In contrast to most light sources, LEDs radiate very little heat in the

form of IR that can cause damage to sensitive objects or fabrics. Wasted energy

is dispersed as heat through the base of the LED.

Slow failure: LEDs mostly fail by dimming over time, rather than the abrupt

failure of incandescent bulbs.

Lifetime: LEDs can have a relatively long useful life. One report estimates

35,000 to 50,000 hours of useful life, though time to complete failure may be

longer. Fluorescent tubes typically are rated at about 10,000 to 15,000 hours,

depending partly on the conditions of use, and incandescent light bulbs at 1,000

to 2,000 hours. Several DOE demonstrations have shown that reduced

maintenance costs from this extended lifetime, rather than energy savings, is the

primary factor in determining the payback period for an LED product.

Shock resistance: LEDs, being solid-state components, are difficult to damage

with external shock, unlike fluorescent and incandescent bulbs, which are

fragile.

Focus: The solid package of the LED can be designed to focus its light.

Incandescent and fluorescent sources often require an external reflector to

collect light and direct it in a usable manner. For larger LED packages total

internal reflection (TIR) lenses are often used to the same effect. However,

when large quantities of light are needed many light sources are usually

deployed, which are difficult to focus or collimate towards the same target.

3.5.3 DISADVANTAGES

High initial price: LEDs are currently more expensive, price per lumen, on an

initial capital cost basis, than most conventional lighting technologies. As of

2012, the cost per thousand lumens (kilolumen) was about $6. The price was

expected to reach $2/kilolumen by 2013. At least one manufacturer claims to

have reached $1 per kilolumen as of March 2014. The additional expense

http://en.wikipedia.org/wiki/Dimmer

http://en.wikipedia.org/wiki/Pulse-width_modulation

http://en.wikipedia.org/wiki/Stroboscopic_effect

http://en.wikipedia.org/wiki/Infrared

http://en.wikipedia.org/wiki/United_States_Department_of_Energy

http://en.wikipedia.org/wiki/Focus_%28optics%29

http://en.wikipedia.org/wiki/Total_internal_reflection

http://en.wikipedia.org/wiki/Total_internal_reflection

http://en.wikipedia.org/wiki/Collimate


SVES 43 ECE Dept.

partially stems from the relatively low lumen output and the drive circuitry and

power supplies needed.

Temperature dependence: LED performance largely depends on the ambient

temperature of the operating environment – or "thermal management"

properties. Over-driving an LED in high ambient temperatures may result in

overheating the LED package, eventually leading to device failure. An adequate

heat sink is needed to maintain long life. This is especially important in

automotive, medical, and military uses where devices must operate over a wide

range of temperatures, which require low failure rates. Toshiba has produced

LEDs with an operating temperature range of -40 to 100 °C, which suits the

LEDs for both indoor and outdoor use in applications such as lamps, ceiling

lighting, street lights, and floodlights.

Voltage sensitivity: LEDs must be supplied with the voltage above the threshold

and a current below the rating. Current and lifetime change greatly with small

change in applied voltage. They thus require a current-regulated supply (usually

just a series resistor for indicator LEDs)

Light quality: Most cool-white LEDs have spectra that differ significantly from

a black body radiator like the sun or an incandescent light. The spike at 460 nm

and dip at 500 nm can cause the color of objects to be perceived differently

under cool-white LED illumination than sunlight or incandescent sources, due

to metamerism red surfaces being rendered particularly badly by typical

phosphor-based cool-white LEDs. However, the color-rendering properties of

common fluorescent lamps are often inferior to what is now available in state-

of-art white LEDs.

Area light source: Single LEDs do not approximate a point source of light giving

a spherical light distribution, but rather a lambertian distribution. So LEDs are

difficult to apply to uses needing a spherical light field; however, different fields

of light can be manipulated by the application of different optics or "lenses".

LEDs cannot provide divergence below a few degrees. In contrast, lasers can

emit beams with divergences of 0.2 degrees or less.

Electrical polarity: Unlike incandescent light bulbs, which illuminate regardless

of the electrical polarity, LEDs will only light with correct electrical polarity.

To automatically match source polarity to LED devices, rectifiers can be used.

http://en.wikipedia.org/wiki/Heat_sink

http://en.wikipedia.org/wiki/Heat_sink

http://en.wikipedia.org/wiki/Black_body

http://en.wikipedia.org/wiki/Color_vision

http://en.wikipedia.org/wiki/Metamerism_%28color%29

http://en.wikipedia.org/wiki/Point_source

http://en.wikipedia.org/wiki/Lambert%27s_cosine_law

http://en.wikipedia.org/wiki/Electrical_polarity

http://en.wikipedia.org/wiki/Incandescent

http://en.wikipedia.org/wiki/Electrical_polarity

http://en.wikipedia.org/wiki/Rectifier


SVES 44 ECE Dept.

Blue hazard: There is a concern that blue LEDs and cool-white LEDs are now

capable of exceeding safe limits of the so-called blue-light hazard as defined in

eye safety specifications such as ANSI/IESNA RP-27.1–05: Recommended

Practice for Ph0tobiological Safety for Lamp and Lamp Systems.

Blue pollution: Because cool-white LEDs with high color temperature emit

proportionally more blue light than conventional outdoor light sources such as

high-pressure sodium vapor lamps, the strong wavelength dependence of

Rayleigh scattering means that cool-white LEDs can cause more light pollution

than other light sources. The International Dark-Sky Association discourages

using white light sources with correlated color temperature above 3,000 K.

Efficiency droop: The luminous efficacy of LEDs decreases as the electrical

current increases. Heating also increases with higher currents which

compromises the lifetime of the LED. These effects put practical limits on the

current through an LED in high power applications.

Impact on insects: LEDs are much more attractive to insects than sodium-vapor

lights, so much so that there has been speculative concern about the possibility

of disruption to food webs.

3.5.4 APPLICATIONS

LED uses fall into four major categories:

Visual signals where light goes more or less directly from the source to the

human eye, to convey a message or meaning.

Illumination where light is reflected from objects to give visual response of

these objects.

Measuring and interacting with processes involving no human vision.

Narrow band light sensors where LEDs operate in a reverse-bias mode and

respond to incident light, instead of emitting light. See LEDs as light sensors.

http://en.wikipedia.org/wiki/Blue-light_hazard

http://en.wikipedia.org/wiki/Color_temperature

http://en.wikipedia.org/wiki/Sodium_vapor_lamp

http://en.wikipedia.org/wiki/Rayleigh_scattering

http://en.wikipedia.org/wiki/Light_pollution

http://en.wikipedia.org/wiki/International_Dark-Sky_Association

http://en.wikipedia.org/wiki/Light-emitting_diode#Efficiency_droop

http://en.wikipedia.org/wiki/Luminous_efficacy

http://en.wikipedia.org/wiki/Electrical_current

http://en.wikipedia.org/wiki/Electrical_current

http://en.wikipedia.org/wiki/Lighting

http://en.wikipedia.org/wiki/LEDs_as_light_sensors


SVES 45 ECE Dept.

CHAPTER-4

SOFTWARE REQUIREMENTS

4.1 INTRODUCTION TO KEIL MICRO VISION (IDE)

Keil an ARM Company makes C compilers, macro assemblers, real-time

kernels, debuggers, simulators, integrated environments, evaluation boards, and

emulators for ARM7/ARM9/Cortex-M3, XC16x/C16x/ST10, 251, and 8051 MCU

families.

Keil development tools for the 8051 Microcontroller Architecture support every

level of software developer from the professional applications engineer to the student

just learning about embedded software development. When starting a new project,

simply select the microcontroller you use from the Device Database and the µVision

IDE sets all compiler, assembler, linker, and memory options for you.

Keil is a cross compiler. So first we have to understand the concept of compilers

and cross compilers. After then we shall learn how to work with keil.

4.2 CONCEPT OF COMPILER

Compilers are programs used to convert a High Level Language to object code.

Desktop compilers produce an output object code for the underlying microprocessor,

but not for other microprocessors. I.E the programs written in one of the HLL like

‘C’ will compile the code to run on the system for a particular processor like x86

(underlying microprocessor in the computer). For example compilers for Dos platform

is different from the Compilers for Unix platform So if one wants to define a compiler

then compiler is a program that translates source code into object code.

The compiler derives its name from the way it works, looking at the entire piece

of source code and collecting and reorganizing the instruction. See there is a bit little

difference between compiler and an interpreter. Interpreter just interprets whole

program at a time while compiler analyses and execute each line of source code in

succession, without looking at the entire program.

The advantage of interpreters is that they can execute a program immediately.

Secondly programs produced by compilers run much faster than the same programs


SVES 46 ECE Dept.

executed by an interpreter. However compilers require some time before an executable

program emerges. Now as compilers translate source code into object code, which is

unique for each type of computer, many compilers are available for the same language.

4.3 CONCEPT OF CROSS COMPILER

A cross compiler is similar to the compilers but we write a program for the target

processor (like 8051 and its derivatives) on the host processors (like computer of x86).

It means being in one environment you are writing a code for another environment is

called cross development. And the compiler used for cross development is called cross

compiler. So the definition of cross compiler is a compiler that runs on one computer

but produces object code for a different type of computer.

4.4 KEIL C CROSS COMPILER

Keil is a German based Software development company. It provides several

development tools like

IDE (Integrated Development environment)

Project Manager

Simulator

Debugger

C Cross Compiler, Cross Assembler, Locator/Linker

The Keil ARM tool kit includes three main tools, assembler, compiler and

linker. An assembler is used to assemble the ARM assembly program. A compiler is

used to compile the C source code into an object file. A linker is used to create an

absolute object module suitable for our in-circuit emulator.

4.5 BUILDING APPLICATIONS IN µVISION2

To build (compile, assemble, and link) an application in µVision2, you must:

Select Project - (for example, 166\EXAMPLES\HELLO\HELLO.UV2).

Select Project - Rebuild all target files or Build target.µVision2 compiles,

assembles, and links the files in your project.


SVES 47 ECE Dept.

4.6 CREATING YOUR OWN APPLICATION IN µVISION

To create a new project in µVision2, you must:

Select Project - New Project.

Select a directory and enter the name of the project file.

Select Project - Select Device and select an 8051, 251, or C16x/ST10 device

from the Device Database™.

Create source files to add to the project.

Select Project - Targets, Groups, and Files. Add/Files, select Source Group1,

and add the source files to the project.

Select Project - Options and set the tool options. Note when you select the target

device from the Device Database™ all special options are set automatically.

You typically only need to configure the memory map of your target hardware.

Default memory model settings are optimal for most applications.

Select Project - Rebuild all target files or Build target.

4.7 DEBUGGING AN APPLICATION IN µVISION2

To debug an application created using µVision2, you must:

Select Debug - Start/Stop Debug Session.

Use the Step toolbar buttons to single-step through your program. You may

enter G, main in the Output Window to execute to the main C function.

Open the Serial Window using the Serial #1 button on the toolbar.

Debug your program using standard options like Step, Go, Break, and so on.

4.8 STARTING µVISION2AND CREATING A PROJECT

µVision2 is a standard Windows application and started by clicking on the

program icon. To create a new project file select from the µVision2 menu Project –

New Project…. This opens a standard Windows dialog that asks you for the new project

file name. We suggest that you use a separate folder for each project. You can simply

use the icon Create New Folder in this dialog to get a new empty folder. Then select

this folder and enter the file name for the new project, i.e. Project1. µVision2 creates a

new project file with the name PROJECT1.UV2 which contains a default target and file

group name. You can see these names in the Project.


SVES 48 ECE Dept.

4.9 WINDOW-FILES

Now use from the menu Project – Select Device for Target and select a CPU for

your project. The Select Device dialog box shows the µVision2 device data base. Just

select the microcontroller you use. We are using for our examples the Philips

80C51RD+ CPU. This selection sets necessary tool Options for the 80C51RD+ device

and simplifies in this way the tool Configuration.

4.10 BUILDING PROJECTS AND CREATING HEX FILES

Typical, the tool settings under Options – Target are all you need to start a new

application. You may translate all source files and line the application with a click on

the Build Target toolbar icon. When you build an application with syntax errors,

µVision2 will display errors and warning messages in the Output Window – Build page.

A double click on a message line opens the source file on the correct location in a

µVision2 editor window. Once you have successfully generated your application you

can start debugging.

After you have tested your application, it is required to create an Intel HEX file

to download the software into an EPROM programmer or simulator. µVision2 creates

HEX files with each build process when Create HEX files under Options for Target –

Output is enabled. You may start your PROM programming utility after the make

process when you specify the program under the option Run User Program #1.

4.11 CPU SIMULATION

µVision2 simulates up to 16 Mbytes of memory from which areas can be

mapped for read, write, or code execution access. The µVision2 simulator traps

and reports illegal memory accesses. In addition to memory mapping, the simulator also

provides support for the integrated peripherals of the various 8051 derivatives. The on-

chip peripherals of the CPU you have selected are configured from the Device.

4.12 DATABASE SELECTION

You have made when you create your project target. Refer to page 58 for more

Information about selecting a device. You may select and display the on-chip peripheral


SVES 49 ECE Dept.

components using the Debug menu. You can also change the aspects of each peripheral

using the controls in the dialog boxes.

4.13 START DEBUGGING

You start the debug mode of µVision2 with the Debug – Start/Stop Debug

Session Command. Depending on the Options for Target – Debug Configuration,

µVision2 will load the application program and run the startup code µVision2 saves the

editor screen layout and restores the screen layout of the last debug session. If the

program execution stops, µVision2 opens an editor window with the source text or

shows CPU instructions in the disassembly window. The next executable statement is

marked with a yellow arrow. During debugging, most editor features are still available.

For example, you can use the find command or correct program errors. Program

source text of your application is shown in the same windows. The µVision2 debug

mode differs from the edit mode in the following aspects:

The “Debug Menu and Debug Commands” described on page 28 are available.

The additional debug windows are discussed in the following.

The project structure or tool parameters cannot be modified. All build commands are

disabled.

4.14 DISASSEMBLY WINDOW

The Disassembly window shows your target program as mixed source and

assembly program or just assembly code. A trace history of previously executed

instructions may be displayed with Debug – View Trace Records. To enable the trace

history, set Debug – Enable/Disable Trace Recording.

If you select the Disassembly Window as the active window all program step

commands work on CPU instruction level rather than program source lines. You can

select a text line and set or modify code breakpoints using toolbar buttons or the context

menu commands.

You may use the dialog Debug – Inline Assembly… to modify the CPU

instructions. That allows you to correct mistakes or to make temporary changes to the

target program you are debugging. Numerous example programs are included to help

you get started with the most popular embedded 8051 devices.


SVES 50 ECE Dept.

The Keil µVision Debugger accurately simulates on-chip peripherals (I²C,

CAN, UART, SPI, Interrupts, I/O Ports, A/D Converter, D/A Converter, and PWM

Modules) of your 8051 device. Simulation helps you understand hardware

configurations and avoids time wasted on setup problems. Additionally, with

simulation, you can write and test applications before target hardware is available.

4.15 EMBEDDED C

Use of embedded processors in passenger cars, mobile phones, medical

equipment, aerospace systems and defense systems is widespread, and even everyday

domestic appliances such as dish washers, televisions, washing machines and video

recorders now include at least one such device.

Because most embedded projects have severe cost constraints, they tend to use

low-cost processors like the 8051 family of devices considered in this book. These

popular chips have very limited resources available most such devices have around 256

bytes (not megabytes!) of RAM, and the available processor power is around 1000

times less than that of a desktop processor. As a result, developing embedded software

presents significant new challenges, even for experienced desktop programmers. If you

have some programming experience - in C, C++ or Java - then this book and its

accompanying CD will help make your move to the embedded world as quick and

painless as possible.


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CHAPTER-5

SCHEMATIC DIAGRAM

Figure 5: Schematic diagram of E notice board


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CHAPTER-6

PROJECT CODE

6.1 SOURCE COD

#include "LPC214x.H" /* LPC21xx definitions */

#include "type.h"

#include "irq.h"

#include "uart.h"

#include "target.h"

#include <stdio.h>

#include<LPC214x.H>

extern DWORD UART0Count;

extern BYTE UART0Buffer[BUFSIZE];

extern DWORD UART1Count;

extern BYTE UART1Buffer[BUFSIZE];

#define UART0_HOST_BAUD 2400

#define UART1_HOST_BAUD 2400

#include <string.h>

#define MAX_BUFF_SZ 10

typedef unsigned char uc;

uc RX_BUFF[MAX_BUFF_SZ];

uc byteCount=0;

typedef unsigned char uc;

#define RDR 0x01

#define THRE 0x20

#define RDA 0x04

int i,msgno,test1,t1,t2,t3,t4;

char s2[10];

char Temp = 0,a=0,cnt7;

unsigned long int lat,lon;

#define RS (1<<21) //Set/Reset Pin (Control_Pin)

#define EN (1<<22)

void Delay(unsigned int );


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void uart0_init(void);

void put_char(uc dt);

void uart1_puts(const unsigned char *str);

int uart0_getc (void);

void _delay_ms(unsigned int k)

{

int i,j;

for(i=0;i<k;i++)

{

for(j=0;j<3000;j++);

}

}

void Delay(unsigned int time)

{

unsigned int i,j;

for(i=0;i<time;i++)

for(j=0;j<25000;j++);

void uart0_putc(char c)

{

while(!(U0LSR & 0x20)); // Wait until UART0 ready to send character

U0THR = c; // Send character

Delay(30);

}

void uart0_puts(char *p)

{

while(*p) // Point to character

{

uart0_putc(*p++); // Send character then point to next character

}

}

int uart0_getc (void)

{

while (!(U0LSR & 0x01));

return (U0RBR);


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}

void uart1_putc(unsigned char data)

{

U1THR = data;

while( (U1LSR&0x40)==0 );

Delay(15);

}

unsigned char uart1_getc()

{

while( (U1LSR&0x01)==0 );

return(U1RBR);

}

void uart1_puts(const unsigned char *str)

{

while(1)

{

if( *str == '\0' ) break;

uart1_putc(*str++);

}

}

void LEDdisplay()

{

IO1SET |=(1<<16)| (1<<17) | (1<<18) |(1<<19)| (1<<20) | (1<<21) |(1<<22);

_delay_ms(2000);

uart1_putc('#');

_delay_ms(2000);

uart1_putc('3')

_delay_ms(2000);

uart1_putc('5');

_delay_ms(2000);

uart1_putc('*');

_delay_ms(2000);


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uart1_puts("<M ");

uart1_puts(s2);

uart1_puts(" >DEF 2><S 1><D L1>");

uart1_putc('\r');

_delay_ms(2000);

IO1CLR |=(1<<16)| (1<<17) | (1<<18) |(1<<19)| (1<<20) | (1<<21) |(1<<22);

_delay_ms(1000);

}

void UART0_ISR(void) irq

{

char v1;

if( U0IIR & RDA) /* Check if Recive data Interrupt event */

{

if(byteCount < MAX_BUFF_SZ) /* Validation for buffer overflow */

{

v1 = U0RBR;

if(v1 == '+')

{

if(uart0_getc() == 'C')

{

if(uart0_getc() == 'M')

{

if(uart0_getc() == 'T')

{

if(uart0_getc() == 'I')

{

if(uart0_getc() == ':')

{

uart0_putc('\r');

Delay(100);

while(uart0_getc() != ',');

msgno=uart0_getc();

while(uart0_getc()!='\r');

uart0_puts("AT");


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for(i=0;i<100;i++)

s2[i]='\0';

uart0_puts("AT+CMGF=1");

uart0_putc('\r');

Delay(100);

uart0_puts("AT+CMGR=");

uart0_putc(msgno);

uart0_putc('\r');

while(uart0_getc()!='?');

for(i=0;(s2[i]=uart0_getc())!='$';i++);

s2[i]=' ';

uart0_putc('\r'); LEDdisplay();

uart0_puts("AT+CMGDA=");

uart0_putc('"');

uart0_puts("DEL ALL");

uart0_putc('"');

uart0_putc('\r');

}

}

}

}

}

}

}

}

VICVectAddr = 0x00;

DWORD UARTInit(BYTE uart_num, DWORD baud )

{

switch(uart_num)

{

case UART0:

PINSEL0 &= ~(0x0000000F);

PINSEL0 |= 0x00000005;


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U0LCR = 0x83;

U0DLL = baud;

U0DLM = (baud >> 8);

U0LCR = 0x03;

U0FCR = 0x07;

if ( install_irq( UART0_INT, (void *)UART0_ISR ) == FALSE )

{

return (FALSE);

}

break;

case UART1:

PINSEL0 &= ~(0x000F0000);

PINSEL0 |= 0x00050000;

U1LCR = 0x83;

U1DLL = baud;

U1DLM = (baud >> 8);

U1LCR = 0x03;

break;

}

return (TRUE);

}

int main (void)

{

int i1,j1;

IODIR1 = 0xffffffff;

IODIR0 =0x00000202;

init_VIC();

UARTInit(UART0,UART_BAUD(UART0_HOST_BAUD));

UARTInit(UART1,UART_BAUD(UART1_HOST_BAUD));

IOCLR1=0X00000000;

U0IER = 0;

uart0_puts("AT");

uart0_putc('\r');


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Delay(100);

uart0_puts("AT+CMGF=1");

uart0_putc('\r');

Delay(100);

uart0_puts("AT+CMGDA=");

uart0_putc('"');

uart0_puts("DEL ALL");

uart0_putc('"');

uart0_putc('\r');

Delay(100);

U0IER = IER_RBR | IER_THRE | IER_RLS;

IO1CLR |=(1<<16)| (1<<17) | (1<<18) |(1<<19)| (1<<20) | (1<<21) |(1<<22);

while (1)

{

}

}


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CHAPTER-7

ADVANTAGES AND APPLICATIONS

7.1 ADVANTAGES

Using GSM mobile we can send message to any distant locations , from any

part of the World.

As it's a GSM wireless transmission system it has very less errors and needs less

maintenance.

Prevents unauthorized access of notice board (password).

Multiple Users are authorized to update notices on the electronic notice board.

No printing and photocopying costs. Thus saves time, Energy and finally

environment.

7.2 DISADVANTAGE

When there is network problem gsm doesn’t work.

7.3 APPLICATIONS

Educational institutions & organizations

Managing traffic

Advertisement Conference hall

Bus/Railway station

Any Public utility places


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CHAPTER-8

CONCLUSION

We can use this Project in college Notice Board, a Professor can send message

for the immediate gathering of students at department. It can be used on Highways

for traffic control, like traffic on one side of the road may be blocked in view of

VVIP movement or jam ahead.

FUTURE SCOPE

The use of microcontroller in place of a general purpose computer allows us to

theorize on many further improvements on this project prototype.

Temperature display during periods wherein no message buffers are empty is

one such theoretical improvement that is very possible.

The ideal state of the microcontroller is when the indices or storage space in the

SIM memory are empty and no new message is there to display.

With proper use of interrupt routines the incoming message acts as an interrupt,

the temperature display is halted and the control flow jumps over to the specific

interrupt service routine which first validates the sender’s number and then

displays the information field.

Another very interesting and significant improvement would be to

accommodate multiple receiver MODEMS at the different positions in a

geographical area carrying duplicate SIM cards.


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CHAPTER-9

BIBLIOGRAPHY

REFERENCES

Ronald K Jurgen “Automotive Electronic Handbook”: New York: McGraw-

Hill, 2nd ed., 1999, Part 7 Chapter 29.

Peter Seiler, Bong sob Song, J. Karl Hedrick “Development of a Collision Avoidance

System”

1998 Society of Automotive Engineers.

General Motors: “The Ultimate Crash Safety is Avoiding Crashes” [online],

http://www.gm.com/company/careers/career_paths/rnd/nws_071800.html.

Daimler-Chrysler: “Safety on the Interstate” [online], available.

http://www.daimlerchrysler.com/dccomDatasheet of NE555.

Datasheet of TSOP1738.

Datasheet of TIP122 and TIP127 [13] www.alldatasheets.com

http://www.gm.com/company/careers/career_paths/rnd/nws_071800.html

http://www.daimlerchrysler.com/dccomDatasheet

http://www.alldatasheets.com/

Main project report on GSM BASED WIRELESS NOTICE BOARD

Education

Transcript of Main project report on GSM BASED WIRELESS NOTICE BOARD