GSM BASED DEVICES CONTROL SYSTEM PROJECT REPORT

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PROJECT REPORT
ON
SMS BASED DEVICES CONTROL SYSTEM USING GSM TECHNOLOGY
Submitted For Partial Fulfilment of Award of
BACHELOR OF TECHNOLOGY in Electrical & Electronics Engineering
[2008-2012]
BY
Richa Shukla
Rituraj
Shriya Mehrotra
Shobhit Chaturvedi
Vishal Kant Rai
UNDER THE GUIDANCE OF
Mr.Vinamra Govil
(Lecturer)
BABU BANARSI DAS NATIONAL INSTITUTE OF TECHNOLOGY&MANAGEMENT
LUCKNOW,INDIA

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UNDERTAKING
We declare that the work presented in this project titled “SMS BASED DEVICES
CONTROL SYSTEM USING GSM TECHNOLOGY” submitted to the Department of
Electrical & Electronics Engineering, Babu Banarsi Das National Institute Of
Technology & Management, Lucknow for the award of the Bachelor of
Technology degree, is our original work .We have not plagiarized or submitted
the same work for the award of any other degree. In case this undertaking is
found incorrect , We accept that our degree may be unconditionally withdrawn.
Date: ……………………….
Place: Lucknow
Richa Shukla
Rituraj
Shriya Mehrotra
Shobhit Chaturvedi
Vishal Kant Rai

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BABU BANARASI DAS NATIONAL INSTITUTE OF
TECHNOLOGY & MANAGEMENT
LUCKNOW- 211004,INDIA
CERTIFICATE
This is to certify that project report entitled “SMS BASED DEVICES CONTROL
SYSTEM USING GSM TECHNOLOGY” presented by RICHA SHUKLA, RITURAJ,
SHRIYA MEHROTRA, SHOBHIT CHATURVEDI, VISHAL KANT RAI students of final
year B.ech in “ELECTRICAL & ELECTRONICS ENGINEERING” are the bonafide
presentation of their work done by them under my supervision and guidance.
They have submitted this project report towards partial fulfillment for the award
of degree of bachelor of technology of the “UTTAR PRADESH TECHNICAL
UNIVERSITY, LUCKNOW” .it is further certified that this work has not being
submitted elsewhere for the award of any degree or diploma.
MR. RAFEEQ AHMAD MR. VINAMRA GOVIL MR. MOHD. SHIBLEE
(PROJECT CO-ORDIN.) (PROJECT GUIDE) (HOD, EN-DEPT.)
LECTURER EN-DEPT LECTURER EN-DEPT B.B.D.N.I.T.M.

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ACKNOWLEDGEMENT
We would like to give our cordial thanks to our project guide Mr. VINAMRA
GOVIL Senior lecturer EN DEPARTMENT, B.B.D. N. I.T.M,Lucknow,for his
regular encouragement,invaluable advice and support without with this project
would never have been completed so smoothly.It is because his regular guidance
and effort,that the whole process has become a success.
We would also like to thanks Mr. MOHD. SHIBLEE, HOD& MR.RAFEEQ
AHMAD, project coordinator, Electrical & Electronics Engineering Department,
B.B.D.N.I.T.M, Lucknow and other faculty members of the department, for their
regular encouragement and support. Without their support ,completion of this
B.Tech.course would not have been possible. They were the driving force and also
the force of inspiration to us.
We would like to thanks our friends Pragati Chaturvedi,Abhinandan
Choudhary,Arun Kumar & special thanx to one of our team member Richa for
their help in completing our project.
Last but not the least We would like to thanks our parents for their indomitable
patients,sacrifice and support without which the successful completion of this work
would have been a distant dream.

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ABSTRACT
The rapidly advancing mobile communication technology and the decrease
incosts make it possible to incorporate mobile technology into home .The project
report on “SMS BASED DEVICE CONTROL IN HOMES” gives an elaborate
view and understanding of the project design and functioning.
The report is divided into parts for explaining the step by step development of the
project. The first part introduces the idea behind the project and the underlying
information of the technologies used. Next chapter is dedicated for information on
the equipments used and how they were accommodated in the project circuitry.
The working of the project with the programming code are explained after that.
Lastly, the merits, de-merits and future prospects of the project are given.

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CONTENTS
ACKNOWLEDGEMENT ………………………….............................................4
ABSTRACT………………………………………………………………………5
LIST OF FIGURE………………………………………………………………...8
Chapter 1 INTRODUCTION…………………………………………………..9
1.1 INTRODUCTION……………………………………………………...10
1 .2 MOTIVATION………………………………………………………...11
1.3 PROBLEM STATEMENT……………………………………………..11
Chapter 2 EQUIPMENT & PCB DESGINING………………………………12
2.1 EQUIPMENTS……………………………………………………………….13
2.1.1 GSM modem……………………………………………………...13
2.1.2 ATMEGA …………………………………………………………15
2.1.3 LIQIUD CRYSTAL DISPLAY(LCD)……………………………20
2.1.4 RELAYS…………………………………………………………..21
2.1.5 ULN 2803…………………………………………………………24
2.2 PCB (PRINTED CIRCUIT BOARD) DESIGNING………………...26
2.2.1 LAYOUT OF THE PROJECT PCB………………………………27
2.2.2 PCB-DESIGNING………………………………………………...28
2.2.2.2CLEANING……………………………………………………..30

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2.2.2.3 ETCHING………………………………………………………31
2.2.2.4 DRILLING……………………………………………………..31
2.2.2.5 SOLDERING…………………………………………………..32
2.2.2.6 MASKING……………………………………………………..32
2.2.3 PCB LAYOUT………………………………………………………32
Chapter 3 COMPONENT LIST……………………………………………..34
3.1 COMPONENT LIST…………………………………………………..35
Chapter 4 WORKING OPERATION & PROGRAMMING CODE……..36
4.1 WORKING…………………………………………………………....37
4.2 CIRCUIT DIAGRAM ………………………………………………...39
4.3 PROGRAMMING CODE…………………………………………….40
Chapter 5 ADVANTAGES & DISADVANTAGES…………………………47
5.1 ADVANTAGES………………………………………………………48
5.2 DISADVANTAGES…………………………………………………..48
Chapter 6 APPLICATIONS…………………………………………………49
6.1 APPLICATIONS……………………………………………………...50
REFERENCES……………………………………………………...51

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LIST OF FIGURES
Figure 1 Gsm Modem………………………………………………………….15
Figure 2 Pin configuration of Atmega…………………………………………18
Figure3 LCD………………………………………………………………….. 21
Figure4 Different types of relay……………………………………………….24
Figure 5 (a) pin connection of uln 2803………………………………………26
Figure 5 (b) plastic package…………………………………………………...26
Figure 6 PCB Layout of soldering side………………………………………28
Figure 7 PCB Layout of Component side…………………………………...28
Figure 8 PCB Designing process……………………………………………..29
Figure 9 PCB cleaning processs ……………………………………………..31
Figure 10 Block Diagram……………………………………………………39
Figure 11 Circuit Diagram..............................................................................40

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INTRODUCTION
1.1 Introduction
In today’s fast changing world, everything is becoming compact, portable and
mobile. The mobile handsets for communication are the biggest advancement in
the area. These have made our lives much simpler and connected. Today almost
everyone is familiar with it’s usage, and is able to draw advantage from it.
The technologies for mobile communication have been ever evolving. Each had
there share of pro’s and con’s. The Global System for Mobile communication
(originally Groupe Spécial Mobile) represents the second generation of mobile
communications. It is a digital telephony system, used in most parts of the world,
starting from Finland in 1991 till now, with more than 690 mobile networks
providing GSM services across 213 countries.
It uses time division multiple access technique (TDMA).GSM digitizes and
compresses data, then sends it down a channel with other streams of user data,
each in its own time slot. It operates at either the 900 MHz or 1800 MHz frequency
band.
GSM provides with Subscribers Identity Module(SIM) to every user.It is a
detachable card which identifies user’s account to the network and provides
authentication, that allows appropriate billing. The unique roaming features of
GSM allow cellular subscribers to use their services in any GSM service area in
the world in which their provider has a roaming agreement. The idea behind the
project is to utilize the mobile nature of communication and application provided
by the GSM technology, namely SMS.SMS stands for Short Messaging Service
.Short Message Service is an integrated paging service that lets GSM cellular

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subscribers send and receive data right on their cellular phone's LED display, up to
a maximum of 160 characters.
The use of SMS makes the understanding and use of the project quite simple to the
user.
1.2 Motivation
As an engineering student a project is required as part of the final year work. The
project chosen is the activation of HomeAutomation via mobile technology. This
was selected because of incorporating mobile technology with controlling of
appliances which we believe is the next important step to realize the Home
Automation. The comfort of being able to take control of devices from one
particular location has become imperative as it saves a lot of time and effort.
1.3 Problem Statement
Technology has advanced so much in the last decade or two that it has made life
more efficient and comfortable. The comfort of being able to take control of
devices from one particular location has become imperative as it saves a lot of time
and effort . Therefore there arises a need to do so in a systematic manner which
we have tried to implement with our system. The system we have proposed is an
extended approach to automating a control system. The application of our system
comes in handy when people who forget to do simple things such as turn ON or
OFF devices at their home or in their office, they can now do so without their
presence by the transmission of a simple text message from their mobile phone.

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CHAPTER 2
EQUIPMENT & PCB
DESGINING

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2.1 EQUIPMENTS:
The different major equipments used in system are enlisted below:
a) GSM modem
b) Microcontroller (ATEMEGA 168)
c) LCD
d) Relay
e) ULN2803
2.1.1 GSM MODEM :
A GSM modem is a specialized type of modem which accepts a SIM card, and
operates over a subscription to a mobile operator, just like a mobile phone. From
the mobile operator perspective, a GSM modem looks just like a mobile phone.
A GSM modem exposes an interface that allows applications such as
NowSMS to send and receive messages over the modem interface. The mobile
operator charges for this message sending and receiving as if it was performed
directly on a mobile phone. To perform these tasks, a GSM modem must support
an ―extended AT command set‖ for sending/receiving SMS messages, as defined
in the ETSI GSM 07.05 and and 3GPP TS 27.005 specifications.
GSM modems can be a quick and efficient way to get started with SMS,
because a special subscription to an SMS service provider is not required. In most
parts of the world, GSM modems are a cost effective solution for receiving SMS
messages, because the sender is paying for the message delivery.
A GSM modem can be a dedicated modem device with a serial, USB or
Bluetooth connection, such as the Falcom Samba 75 used in this document. (Other

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manufacturers of dedicated GSM modem devices include Wavecom, Multitech and
iTegno.)
SIM 300 is a Tri band GSM/GPRS engine that works on frequencies
900MHz, DCS 1800 and 1900MHz. With tiny configuration of
40mmx33mmx2.9mm, SIM 300 can meet almost all the space requirements in
your applications, such as smart phone, PDA phone and other mobile devices. The
physical interface to the mobile application is a 60 pin board t board connector,
which provides all hardware interfaces between the module and customers’ boards
except the RF antenna interfaces.You can turn on the module by driving the
PWRKEY to a low level voltage for period time. The automatic power on circuit
illustrate as following figure. The PWRKEY pin is the NO.34 pin of the module
interface. The value of the capacitor C155 is recommended as
Fig 1 GSM MODEM

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2.1.2ATMEGA 168:
A microcontroller (sometimes abbreviated µC, uC or MCU) is a small
computer on a single integrated circuit containing a processor core, memory, and
programmable input/output peripherals. Microcontrollers are designed for
embedded applications, in contrast to the microprocessors used in personal
computers or other general purpose applications. . By reducing the size and cost
compared to a design that uses a separate microprocessor, memory, and
input/output devices, microcontrollers make it economical to digitally control even
more devices and processes
The Atmel®AVR® core combines a rich instruction set with 32 general
purpose working registers. All the 32 registers are directly connected to the
Arithmetic Logic Unit (ALU), allowing two independent registers to be accessed
in one single instruction executed in one clock cycle. The resulting architecture is
more code efficient while achieving throughputs up to ten times faster than
conventional CISC microcontrollers.
The ATmega8 provides the following features: 8 Kbytes of In-System
Programmable Flash with Read-While-Write capabilities, 512 bytes of EEPROM,
1 Kbyte of SRAM, 23 general purpose I/O lines, 32 general purpose working
registers, three flexible Timer/Counters with compare modes, internal and external
interrupts, a serial programmable USART, a byte oriented Twowire Serial

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Interface, a 6-channel ADC (eight channels in TQFP and QFN/MLF packages)
with 10-bit accuracy, a programmable Watchdog Timer with Internal Oscillator, an
SPI serial port, and five software selectable power saving modes. The Idle mode
stops the CPU while allowing the SRAM, Timer/Counters, SPI port, and interrupt
system to continue functioning. The Powerdown mode saves the register contents
but freezes the Oscillator.
Pin Descriptions
1. VCC
Digital supply voltage.
2 GND
Ground.
3 Port B (PB7:0) XTAL1/XTAL2/TOSC1/TOSC2
Port B is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for
each bit). The Port B output buffers have symmetrical drive characteristics with
both high sink and source capability. As inputs, Port B pins that are externally
pulled low will source current if the pull-up resistors are activated. The Port B pins
are tri-stated when a reset condition becomes active, even if the clock is not
running

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ATmega 8
Fig2 Pin configuration of ATmega 8

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4. Port C (PC5:0)
Port C is a 7-bit bi-directional I/O port with internal pull-up resistors (selected for
each bit). The PC5..0 output buffers have symmetrical drive characteristics with
both high sink and source capability. As inputs, Port C pins that are externally
pulled low will source current if the pull-up resistors are activated. The Port C pins
running.
5. PC6/RESET
If the RSTDISBL Fuse is programmed, PC6 is used as an I/O pin. Note that the
electrical characteristics of PC6 differ from those of the other pins of Port C.
If the RSTDISBL Fuse is unprogrammed, PC6 is used as a Reset input. A
low level on this pin for longer than the minimum pulse length will generate a
Reset.
6. Port D (PD7:0)
Port D is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for
each bit). The Port D output buffers have symmetrical drive characteristics with
both high sink and source capability. As inputs, Port D pins that are externally
pulled low will source current if the pull-up resistors are activated. The Port D pins

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running.
7. AVCC
AVCC is the supply voltage pin for the A/D Converter, PC3:0, and ADC7:6. It
should be externally connected to VCC, even if the ADC is not used. If the ADC is
used, it should be connected to VCC through a low-pass filter.
8. AREF
AREF is the analog reference pin for the A/D Converter.
9.ADC7:6
In the TQFP and QFN/MLF package, ADC7:6 serve as analog inputs to the A/D
converter. These pins are powered from the analog supply and serve as 10-bit
ADC channels.

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2.1.3 LIQIUD CRYSTAL DISPLAY(LCD):
A liquid crystal display (LCD) is a flat panel display, electronic visual display,
or video display that uses the light modulat. LCDs do not emit light directly.LCDs
are used in a wide range of applications ,including computer monitors, television,
instrument panels, aircraft cockpit displays, signage, etc. They are common in
consumer devices such as video players, gaming Fig3 LCD devices, clocks,
watches, calculators, and telephones.
This LCD's typically have 14 data pins and 2 for the LED backlight. Character
LCDs use a standard 14-pin interface and those with backlights have 16 pins.
There is also be a single backlight pin, with the other connection via Ground or
VCC pin. The two backlight pins may precede the pin 1. The nominal backlight
voltage is around 4.2V at 25˚C using a VDD 5V capable model.
Fig 3.LCD

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2.1.3.1 Features :
a) 5 ´ 8 and 5 ´ 10 dot matrix possible
b)Low power operation support:
2.7 to 5.5V
c) Wide range of liquid crystal display driver power
3.0 to 11V
d) 80 ´ 8-bit display RAM (80 characters max.)
2.1.4 Relays:
Relays are electromechanical devices, which are used as a switch. Current flowing
through the coil of the relay creates a magnetic field which attracts a lever and
changes the switch contacts. The main advantages of using relay as a switch is that,
they provide electrical isolation between inputs with the help of magnetic coupling
and also we can handle a large power using a relay.
There are different types of relays are available and they can be categorized in
various ways. For example relays can be SPST, SPDT, DPST, DPDT etc. SPDT
stands for Single Pole
A relay will switch one or more poles, each of whose contacts can be thrown by
energizing the coil in one of three ways:
 Normally-open (NO) contacts connect the circuit when the relay is activated;
the circuit is disconnected when the relay is inactive. It is also called aForm

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A contact or "make" contact. NO contacts can also be distinguished as "early-
make" or NOEM, which means that the contacts will close before the button or
switch is fully engaged.
 Normally-closed (NC) contacts disconnect the circuit when the relay is
activated; the circuit is connected when the relay is inactive. It is also called
aForm B contact or "break" contact. NC contacts can also be distinguished as
"late-break" or NCLB, which means that the contacts will stay closed until the
button or switch is fully disengaged.
 Change-over (CO), or double-throw (DT), contacts control two circuits: one
normally-open contact and one normally-closed contact with a common
terminal. It is also called a Form C contact or "transfer" contact ("break before
make"). If this type of contact utilizes a "make before break" functionality, then
it is called a Form D contact.
The following designations are commonly encountered:
 SPST – Single Pole Single Throw. These have two terminals which can be
connected or disconnected. Including two for the coil, such a relay has four
terminals in total. It is ambiguous whether the pole is normally open or
normally closed. The terminology "SPNO" and "SPNC" is sometimes used to
resolve the ambiguity.

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 SPDT – Single Pole Double Throw. A common terminal connects to either of
two others. Including two for the coil, such a relay has five terminals in total.
 DPST – Double Pole Single Throw. These have two pairs of terminals.
Equivalent to two SPST switches or relays actuated by a single coil. Including
two for the coil, such a relay has six terminals in total. The poles may be Form
A or Form B (or one of each).
 DPDT – Double Pole Double Throw. These have two rows of change-over
terminals. Equivalent to two SPDT switches or relays actuated by a single coil.
Such a relay has eight terminals, including the coil.
Fig 4.Different types of relay

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2.1.5 ULN 2803:
The eight NPN Darlington connected transistors in this family of arrays are ideally
suited for interfacing between low logic level digital circuitry (such as TTL, CMOS
or PMOS/NMOS) and the higher current/voltage requirements of lamps, relays,
printer hammers or other similar loads for a broad range of computer, industrial,
and consumer applications. All devices feature open–collector outputs and
freewheeling clamp diodes for transient Suppression. The ULN2803 is designed to
be compatible with standard families while the ULN2804 is optimized for 6 to 15
volt high level CMOS or PMOS.
MAXIMUM RATINGS (TA = 25°C and rating apply to any one device in the
package, unless otherwise noted.)
Rating Symbol Value Unit
Output Voltage VO 50 V
Input Voltage VI 30 V
Collector Current – Conti. IC 500 mA
Base Current – Continuous IB 25 Ma

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(B)
(A)
Fig 5 (A)pin connection of uln 2803 (B) plastic package

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2.2PCB (PRINTED CIRCUIT BOARD) DESIGNING:
A printed circuit board, or PCB, is used to mechanically support and electrically
connect electronic components using conductive pathways, tracks or traces etched
from copper sheets laminated onto a non-conductive substrate. It is also referred to
as printed wiring board (PWB) or etched wiring board. A PCB populated with
electronic components is a printed circuit assembly (PCA), also known as a printed
circuit board assembly (PCBA)
PCBs are inexpensive, and can be highly reliable. They require much more layout
effort and higher initial cost than either wire-wrapped or point-to-point constructed
circuits, but are much cheaper and faster for high-volume production. Much of the
electronics industry's PCB design, assembly, and quality control needs are set by
standards.

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2.2.1 LAYOUT OF THE PROJECT PCB
2.2.1.A Solder side of the PCB
Fig6: PCB Layout of soldering side
2.2.1.b Component side of the PCB:
0 Fig 7:PCB Layout of Component side

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2.2.2PCB-DESIGNING
PCB Designing includes the following steps:-
Fig8 : PCB Designing process
CLEANSING
ETCHING
DRILLING
PROCESSING
PRINTING
SOLDERING
MASKING

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2.2.2.1PROCESSING
The layout of a PCB has to incorporate all the information on the board before one
can go on to the artwork preparation. This means that a concept that clearly defines
all the details of the circuit and partly also of the final equipment, is a prerequisite
before the actual layout can start. The detail circuit diagram is very important for
the layout designer and he must also be familiar with the design concept and with
the philosophy behind the equipment. The General Considerations are-
a-) Layout scale:- Depending on the accuracy required, artwork should be
produced at a 1:1 or 2:1 or even 4:1 scale. The layout is best prepared on the same
scale as the artwork. This prevents all the problems which might be caused by
redrawing of layout to the artwork scale.
b-) Grid system or Graph Paper: - It is commonly accepted practice to use
these for designing.
c-) Board types:-There are two side of a PCB board – Component side &
Solder side. Depending on these board are classified as-
Single-sided Boards: - These are used where costs have to be kept at a
minimum & a particular Circuit can be accommodated on such board. To
jump over conductor tracks, components have to be utilized. If this is not

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feasible, jumper wires are used. (Jumper wires should be less otherwise
double-sided PCB should be considered.
Double-sided Boards: - These are made with or without plated through
holes. Plated through holes are fairly expensive.
2.2.2.2CLEANING
The cleaning of the copper surface prior to resist application is an essential step for
any type of PCB process using etches or plating resist.After scrubbing with the
abrasive, a water rinse will remove most of the remaining slurry.
Fig 9: PCB cleaning process
Scrubbing
Water Rinse
Wet Brushing
Acid dip
Final Rinse
Drying
Pumice/ Acid Slurry
Tap Water
Tap Water
Hydrochloric Acid-HCl
De-ionized Water
Oven or Blowing of air.

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2.2.2.3 ETCHING
It is of utmost importance to choose a suitable Etchant Systems. There are many
factors to be considered:-
 Etching speed
 Copper solving capacity
 Etchant price
 Pollution character
We have uses FeCl3 (Conc. 120 g/litre 0.1 M) for etching.
2.2.2.4 DRILLING
The importance of hole drilling into PCB’s has further gone with electronic
component miniaturization and its need for smaller holes diameters (diameters less
than half the board thickness) and higher package density.
The following hole diameter tolerances have been generally accepted wherever no
other specifications are mentioned.
Hole Diameter (D) <= 1mm + / - 0.05 mm
Hole Diameter (D) > 3 mm + / – 0.1 mm

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2.2.2.5 SOLDERING
Flux should be removed after Soldering. It is done through washing by 0.5—1 %
HCl followed by Neutralization in dilute alkali to remove corrosive flux.Non-
corrosive is removed by Iso-Propanal.
2.2.2.6 MASKING
It is done for the protection of conductor track from Oxidation.
2.2.3 PCB LAYOUT
A PCB layout is required to place components on the PCB so that the component
area can be minimized and the components can be placed in an efficient manner.
The components can be placed in two ways, either manually or by software. The
manual procedure is quiet cumbersome and is very inefficient. The other method is
by the use of computer software. This method is advantageous as it saves time and
valuable copper area. There are various software’s available for this purpose like-
 Express PCB
 Pad2pad
 Protel PCB
 PCB design e.t.c.

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Many of them are loaded with auto routing and auto placement facility. The
software that we have used here is EXPRESS PCB. This software has a good
interface, easy editing options and a wide range of components.
Express P.C.B.
Express PCB is a very easy to use Windows application for laying out
printed circuit boards. There are two parts to Express PCB, Express SCH for
drawing schematics and Express PCB for designing circuit boards. We
downloaded the software from the website www.expresspcb.com.
There are lots of functions available in the software. This software is free of
cost and it is very easy to use. The different layers of the PCB can be viewed by
just a click of a button on the interface. And we easily get its print on paper which
is utilized for further processing. We can design single sided PCB as well as
Double Sided PCB with this Software.

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3.COMPONENT PART LIST
The list of component used is enlisted below :
COMPONENT MODEL QUANTITY
GSM modem SIM 300 1
Microcontroller ATMEGA 168 1
Interfacing device ULN 2803 1
Relay JIH JIK 4
LCD HD44780U 1
LED 6
Variable resistance 1
Voltage Regulator LM 7805 1
Diode IN 4007 2
Resistance 1Kohm 6
Resistance 10Kohm 1
Crystal oscillator(10
MHz)
1
Ceramic capacitor 104/AEC 1
Ceramic capacitor 33/AEC 2
Connector 9
Connecting wires
Relay JQC-3FC 4

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CHAPTER 4
WORKING OPERATION &
PROGRAMMING CODE

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4 WORKING OPERATION & PROGRAMMING CODE
This chapter deals with working of ―sms based control system using GSM
MODEM‖. This chapter also introduces programming used in microcontroller.
4.1 WORKING:
The idea behind this project is to use the existing GSM infrastructure. So, all the
operations involve the gsm system also. As we send any sms, it goes through the
gsm system. Any sent sms can be received if we use a SIM card and gsm module.
To operate any gsm modem, we have to use the AT commands to operate them.
For example, if any sms arrives the gsm modem sends the serial data in ASCII
format. We can read these data if we connect the modem with the serial port of the
microcontroller at the baud rate of 9600. As the microcontroller comes to know
that a sms has been arrived, it can sent a proper AT command to read the sms. The
reading of sms returns the mobile no of sender, the time and much more
information. We have to select the sms part of the message. The starting string of
the sms is used as the password. As the password is matched, then the sms arrival
is assumed to be valid by the microcontroller otherwise, it ignores the
sms.Working of ―sms based device control system using GSM MODEM‖ is very
simple.It can be simply understood by its block diagram &circuit diagram.

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4.2 CIRCUIT DIAGRAM :
Fig10. circuit diagram

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4.3 PROGRAMMING CODE:
ATMEGA 168 operate for both analog as well as digital signal.programming of
this microcontroller is done in compiler ARDUINO which is open source free
compiler.Programing code is written below:
// all the sms should start with # and terminate with *.
#include <LiquidCrystal.h>
#include <NewSoftSerial.h>
#define led_pin 8
#define buzz_pin 9
LiquidCrystal lcd(2, 3, 4, 5, 6, 7);
NewSoftSerial gsm(18,19);// connect the gsm module here
String str="";
//String sent_sms="ok";
String status_string="OK";
//String sms_arrival="+CMTI: "+ String(char(34)) + "SM" + String(char(34));
//String mob_no="";
String sms="";
const char sms_end='*';
int stage=0;
char ch;
int i=-1;
void setup()

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{ lcd.begin(16, 2);
// lcd.print("GSM BASED SYSTEM");
indicate(1000);
gsm.begin(2400);// keep the speed of the modem slow to handle the data easily
gsm.print("atnr"); // ATTENTION
delay(100);
gsm.print("ate0nr"); // ECHO OFF
delay(100);
gsm.print("at+cmgf=1nr");// SMS FORMAT TEXT
delay(100);
gsm.print("at+cnmi=2,1,0,1,0nr"); // indicates the arrival of new message
delay(1000);
gsm.flush(); // CLEAR THE INITIAL DATA OF MODEM
delay(1000);
gsm.print("at+cmgd=1nr"); // CLEAR THE LOCATION 1
pinMode(11,OUTPUT);
digitalWrite(11,LOW);
pinMode(14,OUTPUT);
pinMode(15,OUTPUT);
pinMode(17,OUTPUT);
pinMode(16,OUTPUT);
lcd.clear();
lcd.print("DEVICE CONTROL");
}
void loop()

42
{
while(stage==0) // hold here unless otherwise any sms arrives
{ if(gsm.available())
{ ch=char(gsm.read());
str+=ch;
i=str.indexOf("+CMTI: ");
if(i>=0) // only when sms gets arrived
{ //Serial.println("SMS ARRIVED");
lcd.clear();
lcd.print("SMS ARRIVED");
str="";
gsm.print("at+cmgr=1nr");// comman to read the sms
stage=1;// now we shall read the sms
i=-1
indicate(100);
lcd.clear();
}
}
}
while(stage==1)
{
if(gsm.available())
{ ch=gsm.read();
// Serial.print(ch);
lcd.print(ch);

43
str+=ch;
if(ch==sms_end)// termination character found
{stage=2;
indicate(100);
}
}
}
while(stage==2)
{
for(i=((str.indexOf('#')+1));(i<str.indexOf('*'));i++) // sms starts with # and ends with *
{ sms+=str.charAt(i);
}
indicate(1000);
lcd.clear();
lcd.print("GSM BASED SYSTEM");
lcd.setCursor(0,1);
lcd.print(sms);
indicate(200);
for(int n=0;n<=3;n++)
{
int pin=14+n;
int data=sms[n]-'0';
digitalWrite(pin,data);
}

44
//******************************
str="";// clear the string
gsm.print("at+cmgd=1nr");//clear the locatin 1
}// stage 2
while(stage==3)
{
if(gsm.available())
{ ch=gsm.read();
// Serial.print(ch);
str+=ch;
if((str.indexOf("OK")>0))
{ str="";
status_string="OK";
// mob_no="";
sms="";
stage=4;
i=-1;
indicate(100);
delay(2000);
send_sms();
delay(1000);
}
}
}// stage 3

45
while(stage==4) //
{
if(gsm.available())
{
ch=gsm.read();
Serial.print(ch);
str+=ch;
if((str.indexOf("OK")>0))
{ str="";
stage=0;
lcd.clear();
lcd.print("DEVICE CONTROL");
}
}
}
}//main loop
void indicate(int i)
{
digitalWrite(led_pin, HIGH);
digitalWrite(buzz_pin, HIGH);
delay(i);
digitalWrite(led_pin, LOW);
digitalWrite(buzz_pin, LOW);
}

46
void send_sms()
{ gsm.print("ATnr");
gsm.print("AT+CMGS=");
gsm.print(char(34));
gsm.print("+9197932022 58");
gsm.print(char(34));
gsm.print("nr");
delay(100);
gsm.print("OK");
gsm.print(char(26)); // ascii code for ctrl^z
// sent_sms="OK"; //

47
CHAPTER 5
ADVANTAGES &
DISADVANTAGES

48
5 ADVANTAGES & DISADVANTAGE
This project is made with best of capabilities and dedication. Details were taken
care of in preparing it. The problems encountered in various steps were taken into
account and eliminated to much extent so that they may not harm the project
functioning. Also certain areas were thought of before hand and worked upon, so
as to prevent them from becoming a limitation for the project. But, as it is that
every system is not perfect in all the aspects. They have some associated
limitations. Here are presented the advantages, in general and comparative of the
counterparts, and disadvantages of the project.
5.1ADVANTAGES:
1. Devices can be controlled from long distances.
2. Economical design
3. Can be easily implemented in homes
4. Can be used by everyone with just the knowledge of text SMS
5. Format of the SMS is simple to understand and write.
5.2DISADVANTAGES:
1. The system is network dependent. Hence, network congestion can reduce the
00 reliability of the system.
2. User can make mistake while typing the message format.

50
6.1 APPLICATIONS
The previous chapter deal with stated merits and de-merits of the project, the
project can be put for use in following fields-
1. Home automation, which was the seed for developing the idea of project.
2. Remote device control. a) This will help to eliminate need of human
personnel attending the device till it has to be switched off/on. Based on
experience of approximate time to switch on/off ,he/she can control the
device, saving time.
b) It will also help to control device while attending to other work.
c) User can control device in case of forgetting to do so while leaving for
some other place.
3. Energy conservation
4. Irrigation systems

51
REFERNCES:
1. Paper of M.J Vanderwerff on ―activation of home automation system via
mobile technology‖
2. Wikipedia-GSM technology
3. Data sheet of ATMEGA 168
4. www.motorola.com-interfacing device information
5. Dr. Aditya Trivedi-Prof. IIIT Gwalior
6. Labsguru workshop –programming details

GSM BASED DEVICES CONTROL SYSTEM PROJECT REPORT

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