1 Introduction

In this project we are monitoring a security system using PIR location using GSM modem. There shall be an automatic call/sms from the system to the police or to any other person when any security is broken sensitive places like banks. Hence the user gets automatic information as soon as some problem occurs at the station.

A security system is designed with the help of IR transmitters and receivers/PIR. If there is any violation in the system, the data microcontroller senses it, and sends sms to the user.

Fig1.1 Hardware Circuit Of GSM Modem

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Fig1.2 Hardware Circuit Of PIR Based Security System

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2. Block Diagram

Fig.2.1 : Block Diagram

2.1 Block Diagram Description

A) Input Section:

PIR sensor/IR sensor:

The PIR (Passive Infra-Red) Sensor is a pyroelectric device that detects motion by

measuring changes in the infrared (heat) levels emitted by surrounding objects. When motion

is detected the PIR sensor outputs a high signal on its output pin. This logic signal can be

read by a microcontroller or used to drive an external load.

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PIR based sensing unit

Interfacing

MOBILE PHONE

GSM

MODULE

Microcontroller

Receiving mobile of authenticated user

Transmitting Modem

B) Processing Section:

Microcontroller: Programmed by the user to monitor the input and generate proper output for the output unit. In general this is the brain of the system.

C) Output Section:

16x2 LCD: Used as display device for required data. Telephonic Network: GSM communication scheme/system Buzzer system : This will generate the alarm in case of leakage GSM modem (transmitting end): The modem will send the text message to the registered

mobile number when leakage is detected.

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3. Circuit Diagram

Fig. 3.1: PIR Circuit diagram

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GSM Modem Circuit

Fig. 3.2: GSM modem circuit diagram

4. Component Study

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4.1 Hardware Component

4.1.1 PIR Sensor

A) INTRODUCTION:

The PIR (Passive Infra-Red) Sensor is a pyroelectric device that detects motion by measuring

changes in the infrared (heat) levels emitted by surrounding objects. When motion is detected

the PIR sensor outputs a high signal on its output pin. This logic signal can be read by a

microcontroller or used to drive an external load.

Longer detection range, selectable by onboard jumper

Wider supply voltage, from 3 to 6 VDC

Higher output current provides for direct control of an external load

Mounting holes included for permanent projects

All parts SMT

PIR sensors allow you to sense motion, almost always used to detect

whether a human has moved in or out of the sensors range. They are small, inexpensive, low-

power, easy to use and don't wear out. For that reason they are commonly found in appliances

and gadgets used in homes or businesses. They are often referred to as PIR, "Passive

Infrared", "Pyroelectric", or "IR motion" sensors.

Fig.4.1.1: PIR Sensor

PIRs are basically made of a pyroelectric sensor (which you can see above as the round metal

can with a rectangular crystal in the center), which can detect levels of infrared radiation. Everything

emits some low level radiation, and the hotter something is, the more radiation is emitted. The sensor

in a motion detector is actually split in two halves. The reason for that is that we are looking to detect

motion (change) not average IR levels. The two halves are wired up so that they cancel each other

out. If one half sees more or less IR radiation than the other, the output will swing high or low.

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B) HOW IT WORKS?

The PIR sensor itself has two slots in it; each slot is made of a special material that is

sensitive to IR. The lens used here is not really doing much and so we see that the two slots

can 'see' out past some distance (basically the sensitivity of the sensor). When the sensor is

idle, both slots detect the same amount of IR, the ambient amount radiated from the room or

walls or outdoors.

Fig4.1.2: Working of PIR

When warm bodies like a human or animal passes by the sensor, it first intercepts one half of

the PIR sensor, which causes a positive differential change between the two halves. When the

warm body leaves the sensing area, the reverse happens, whereby the sensor generates a

negative differential change. These change pulses are what is detected.

C) TECHNICAL DATA:

Power requirements: 3 to 6 VDC; 12 mA @ 3 V, 23 mA @ 5 V

Communication: Single bit high/low output

Dimensions: 1.41 x 1.0 x 0.8 in (35.8 x 25.4  x 20.3 cm)

Operating temp range: 32 to 122 °F (0 to 50 °C)

D) APPLICATIONS:

Motion-activated nightlight

Alarm systems

Holiday animated props

Motion based security system

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4.1.2 GSM MODEM

A) INTRODUCTION

GSM (Groupe Spéciale Mobile, now named Global System for Mobile Communications) is a 2nd Generation cellular mobile system innovated in Europe by ETSI (European Telecommunications Standardization Institute). It is now a “family name” of a number of systems including 2.5G and 3G systems such as:

PCS (Personal Cellular System/Service) – North American GSM

HSCSD (High-Speed Circuit Switched Data) – GSM with high-speed data by bundling up to four voice equivalentchannels

GPRS (General Packet Radio Services) – GSM enhancement in cell-phone software and network hardware and

software to support packet switching (the one used by the Internet)

EDGE (Enhanced Data rates for GSM Evolution) – a technique to achieve better ‘compression’ of data on the airinterface

EGPRS (EDGE based GPRS)

UMTS (Universal Mobile Telecommunications Service) – 3G System based on W-CDMA (Wideband Code Division Multiple Access)

HSPA (High Speed Packet Access) – Data speed enhancement for 3G systems

3GSM (3rd

Generation GSM) – new name for 3G systems that are based on GSM technologies

The development of GSM started in 1982 when a study group ‘Group Special Mobile’ was

formed during Conference of European Posts and Telegraphs (CEPT) this group was to develop a

Pan-European public cellular system in the 900 MHz range. Some of the basic criteria for their

proposed system were:

Good subjective speech quality

ISDN compatibility

Spectral efficiency

Support for international roaming

Support for range of new services and facilities

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In 1989, GSM responsibility was transferred to European Telecommunication Standards

Institute (ETSI) and commercial service was started in mid 1991. Although GSM was

standardized in Europe, now it is operational in other continents also. The acronym

GSM now aptly stands for Global System for Mobile Communication.

B) SYSTEM ARCHITECTURE:

The functional architecture of a GSM system can be broadly classified into

Mobile Station (MS)

Base Station Subsystem (BSS)

Network and Switching Subsystem (NSS)

Operation Subsystem (OSS)

The MS and the BSS communicate via the Um interface or radio link. The BSS

communicates with Mobile Service Switching Center across the A interface.

Fig 4.1.3: GSM Architecture

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C) GSM MODULE

Designed for global market, SIM300 is a Tri-band GSM/GPRS engine that works on frequencies EGSM 900 MHz, DCS 1800 MHz and PCS 1900 MHz SIM300 features GPRS multi-slot class10/ class 8 (optional) and supports the GPRS coding schemes CS-1, CS-2, CS-3 and CS-4. With a tiny configuration of 40mm x 33mm x 2.85mm, SIM300 can fit almost all the space requirements in our application, such as smart phone, PDA phone and other mobile devices. In this hardware SIM300 is only interfaced with RS232, Regulated power Supply 4.0V SIM Tray Antenna with LED indications.

Fig.4.1.4: GSM Module

A: SIM300 module interface

B: SIM card interface

C: headset interface

D: Download switch, turn on or off download function

E: VBAT switch, switch the voltage source from the adaptor or external battery

F: PWRKEY key, turn on or turn off SIM300

G: RESET key

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H: expand port, such as keypad port, main and debug serial port, display port

I: MAIN serial port for downloading, AT command transmitting, data exchanging

J: DEBUG serial port

K: hole for fixing the antenna

L: source adapter interface

M: light 

N: buzzer 

O: headphones interface

P: hole for fixing the SIM300

4.1.3 ATMEGA 168/328 Microcontroller:

A) INTRODUCTION:

The computer on one hand is designed to perform all the general purpose tasks on a single machine like you can use a computer to run a software to perform calculations or you can use a computer to store some multimedia file or to access internet through the browser, whereas the microcontrollers are meant to perform only the specific tasks, for e.g., switching the AC off automatically when room temperature drops to a certain defined limit and again turning it ON when temperature rises above the defined limit.

There are number of popular families of microcontrollers which are used in different applications as per their capability and feasibility to perform the desired task, most common of these are 8051, AVR and PIC microcontrollers. In this we will introduce you with AVR family of microcontrollers.

B) FEATURES:

o RISC Architecture with CISC Instruction set

o Powerful C and assembly programming

o Scalable

o Same powerful AVR microcontroller core

o Low power consumption

o Both digital and analog input and output interfaces

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C) PROCESSOR ARCHITECTURE

Fig. 4.1.5 : Processor Architectures

AVR follows Harvard Architecture format in which the processor is equipped with separate memories and buses for Program and the Data information. Here while an instruction is being executed, the next instruction is pre-fetched from the program memory.

ALU: The high-performance AVR ALU operates in direct connection with all the 32 general purpose working registers. Within a single clock cycle, arithmetic operations between general purpose registers or between a register and an immediate are executed. The ALU operations are divided into three main categories – arithmetic, logical, and bit-functions. Some implementations of the architecture also provide a powerful multiplier supporting both signed/unsigned multiplication and fractional format.

In-system reprogrammable flash program memory: The ATmega48/88/328 contains 4K/8K/16K bytes On-chip In-System Reprogrammable Flash memory for program storage. Since all AVR instructions are 16 or 32 bits wide, the Flash is organized as 2K/4K/8K × 16. For software security, the Flash Program memory space is divided into two sections, Boot Loader Section and Application Program Section in ATmega88 and ATmega328.

EEPROM data memory: The Atmel ATmega48 /88/328 contains 256/512/512 bytes of data EEPROM memory. It is organized as a separate data space e, in which single bytes can be read and written. The EEPROM has an endurance of at least 100,000 write/erase cycles. The

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access between the EEPROM and the CPU is described in the following, specifying the EEPROM Address Registers, the EEPROM Data Register, and the EEPROM Control Register.

Program counter: A program counter is a register in a computer processor that contains the address (location) of the instruction being executed at the current time. As each instruction gets fetched, the program counter increases its stored value by 1. After each instruction is fetched, the program counter points to the next instruction in the sequence. When the computer restarts or is reset, the program counter normally reverts to 0. In computing, a program is a specific set of ordered operations for a computer to perform. An instruction is an order given to a computer processor by a program. Within a computer, an address is a specific location in memory or storage. A register is one of a small set of data holding places that the processor uses. Program counter is very important feature in the microcontrollers.

RAM: RAM stands for random access memory. This type of memory storage is temporary and volatile. You might have heard that if your system is working slowly you say that increase the RAM processing will increase. Let us understand in detail. Let us consider two cases to execute a task first the complete task is execute at one place(A), second the task is distributed in parts and the small tasks are executed at different places(A,B C)and finally assembled. It is clear the work will be finished in second case earlier. The A, B, C basically represent different address allocation for temporary processing. This is the case with RAM also if you increase the RAM the address basically increases for temporary processing so that no data has to wait for its turn. On major importance of the RAM is address allocations. However the storage is temporary every time u boot your system the data is lost but when you turn on the system The BIOS fetch number of addresses available in the RAM. This memory supports read as well as write operations both.

Instruction execution section (IES). It has the most important unit—instruction register and

instruction decoder to control the flow of the instruction during the processing’s.

INPUT/OUTPUT PORTS: To interact with the physical environment there are different input and output ports in every system like in PC we have VGA port to connect the monitor, USB port for flash memory connections and many more ports. Similarly ATMEGA 328 has its input and output ports with different configurations depending on the architecture like only input, only output and bi-directional input output ports. The accessing of this port is referred as input output interface design for microcontrollers. IT has analog input port, analog output port, digital input port ,digital output port, serial communication pins, timer execution pins etc.

Analog Comparator & A/D converters: The major question is that how a controller manage to detect variation of voltage in-spite it could not understand the voltage but understand only digital sequence

Most of the physical quantities around us are continuous. By continuous we mean that the quantity can take any value between two extreme. For example the atmospheric temperature can take any value (within certain range). If an electrical quantity is made to vary directly in proportion to this value (temperature etc) then what we have is Analogue signal. Now we have we have brought a physical quantity into electrical domain. The electrical quantity in most case is voltage. To bring this quantity into digital domain we have to convert this into

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digital form. For this a ADC or analog to digital converter is needed. Most modern MCU including AVRs has an ADC on chip. An ADC converts an input voltage into a number. An ADC has a resolution. A 10 Bit ADC has a range of 0-1023. (2^10=1024) The ADC also has a Reference voltage (ARef). When input voltage is GND the output is 0 and when input voltage is equal to ARef the output is 1023. So the input range is 0-ARef and digital output is 0-1023.

Inbuilt ADC of AVR

Now you know the basics of ADC let us see how we can use the inbuilt ADC of AVR MCU. The ADC is multiplexed with PORTA that means the ADC channels are shared with PORTA. The ADC can be operated in single conversion and free running more. In single conversion mode the ADC does the conversion and then stop. While in free it is continuously converting. It does a conversion and then start next conversion immediately after that.

ADC Pre-scalar.

The ADC needs a clock pulse to do its conversion. This clock generated by system clock by dividing it to get smaller frequency. The ADC requires a frequency between 50 KHz to 200 KHz. At higher frequency the conversion is fast while a lower frequency the conversion is more accurate. As the system frequency can be set to any value by the user (using internal or externals oscillators) (In board™ a 16MHz crystal is used). So the Pre-scalar is provided to produces acceptable frequency for ADC from any system clock frequency. System clock can be divided by 2, 4,16,32,64,128 by setting the Pre-scalar.

ADC Channels

The ADC in ATmega328 has 6 channels that mean you can take samples from eight different terminals. You can connect up to 8 different sensors and get their values separately.

D) PIN DIAGRAM & DESCRIPTION

PIN DESCRIPTION:VCC: Digital supply voltage.GND: Ground. Port B (PB7:0) XTAL1/XTAL2/TOSC1/TOSC2Port 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. Depending on the clock selection fuse settings, PB6 can be used as input to the inverting Oscillator amplifier and input to the internal clock operating circuit. Depending on the clock selection fuse settings, PB7 can be used as

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output from the inverting Oscillator amplifier. If the Internal Calibrated RC Oscillator is used as chip clock source, PB7.6 is used as TOSC2.1 input for the Asynchronous Timer/Counter2 if the AS2 bit in ASSR is set.

Fig. 4.1.6 PIN diagram of Atmega168

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 are tri-stated when a reset condition becomes active, even if the clock is not running.

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 un-programmed, PC6 is used as a Reset input. A low level on this pin for longer than the minimum pulse length will generate a Reset, even if the clock is not running. Shorter pulses are not guarantee to generate a reset.

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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 are tri-stated when a reset condition becomes active, even if the clock is not running.

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. Note that PC6.4 use digital supply voltage, VCC.

AREF: AREF is the analog reference pin for the A/D Converter.

E) MINIMUM INTERFACE CIRCUIT FOR ATMEGA168 CONTROLLER:

The minimum interface circuit for ATMEGA168 is:

Fig. 4.1.7 Interface Circuit of Atmega 168

4.1.4 Crystal Oscillator

A) INTRODUCTION:

A crystal oscillator is an electronic circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency. This

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frequency is commonly used to keep track of time (as in quartz wristwatches), to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for radio transmitters and receivers. The most common type of piezoelectric resonator used is the quartz crystal, so oscillator circuits designed around them were called "crystal oscillators".

A crystal oscillator is an electronic circuit that produces electrical oscillations at a particular designed frequency determined by the physical characteristics of one or more crystals, generally of quartz, positioned in the circuit feedback loop. A piezoelectric effect causes a crystal such as quartz to vibrate and resonate at a particular frequency. The quartz crystal naturally oscillates at a particular frequency, its fundamental frequency that can be hundreds of megahertz. The crystal oscillator is generally used in various forms such as a frequency generator, a frequency modulator and a frequency converter.

Fig. 4.1.8 Crystal Oscillator

The crystal oscillator utilizes crystal having excellent piezoelectric characteristics, in which crystal functions as a stable mechanical vibrator. There are many types of crystal oscillators. One of them is a crystal oscillator employing an inverting amplifier including a CMOS (complementary metal oxide semiconductor) circuit, and used, for example, as a reference signal source of a PLL (phase-pocked poop) circuit of a mobile phone. Crystal oscillator circuits using crystal have a number of advantages in actual application since crystals show high frequency stability and stable temperature characteristic as well as excellent processing ability. Temperature-compensated crystal oscillators, in which variation in oscillation frequency that arises from the frequency-temperature characteristic of the quartz-crystal unit is compensated, find particularly wide use in devices such as wireless phones used in a mobile environment. A surface mounting crystal oscillator is used mainly as a frequency reference source particularly for a variety of portable electronic devices such as portable telephones because of its compact size and light weight.

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B) CRYSTAL OSCILATORS OF DIFFERENT FREQUENCIES WITH USES

Frequency (MHz)  Primary uses 

0.032768Real-time clocks, quartz watches and clocks; allows binary division to 1 Hz signal (215 × 1 Hz)

1.8432UART clock; allows integer division to common baud rates. (= 213 × 32 × 52. 16 × 115200 baud or 96 × 16 × 1200 baud)

2.4576 UART clock; allows integer division to common baud rates up to 38400

3.2768 Allows binary division to 100 Hz (32768 × 100 Hz, or 215 × 100 Hz)3.575611 PAL M color subcarrier

3.579545NTSC M color subcarrier. Because these are very common and inexpensive they are used in many other applications, for example DTMF generators

3.582056 PAL N color subcarrier3.6864 UART clock (2 × 1.8432 MHz); allows integer division to common baud rates

4.096 Allows binary division to 1 kHz (212 × 1 kHz)

C) CRYSTAL OSCILLATORS USED IN MICROCONTROLLERS

A microcontroller is disclosed that includes a crystal oscillator circuit that is programmable to provide multiple different levels of start-up current. In the present embodiment, the crystal oscillator circuit includes logic devices for receiving programming indicating one of a plurality of different start-up current levels and a resistor chain. The logic devices are coupled to the resistor chain for controlling the resistance of the oscillator circuit such that, upon receiving programming indicating a particular start-up current level, the crystal oscillator circuit generates a corresponding start-up current. In addition, the crystal oscillator circuit includes provision for selecting one of a plurality of different levels of capacitance. Furthermore, the crystal oscillator circuit includes a gate pass that includes circuitry for assuring predetermined start-up conditions are met. A feedback loop that includes an amplifier provides for steady- state operation that have low power consumption

4.1.5 Buzzer

A) INTRODUCTION:

A buzzer or beeper is an audio signalling device, which may be mechanical,

electromechanical, or piezoelectric. Typical uses of buzzers and beepers include alarm

devices, timers and confirmation of user input such as a mouse click or keystroke.

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Fig.4.1.9 Buzzer

Mechanical

A joy buzzer is an example of a purely mechanical buzzer.

Electro-mechanical

Early devices were based on an electromechanical system identical to an electric bell without the metal gong. Similarly, a relay may be connected to interrupt its own actuating current, causing the contacts to buzz. Often these units were anchored to a wall or ceiling to use it as a sounding board. The word "buzzer" comes from the rasping noise that electromechanical buzzers made.

Piezoelectric

A piezoelectric element may be driven by an oscillating electronic circuit or other audio signal source, driven with a piezoelectric audio amplifier. Sounds commonly used to indicate that a button has been pressed are a click, a ring or a beep.

B) BUZZER INTERFACING:

If the proper potential is provided across the buzzer it generates the sound else not. It is of two pin configuration that is anode (+) and cathode (-). For interfacing to any device like controller etc. we directly connect the cathode to the GND and anode to the device like controller .Now when signal on anode goes high buzzer activates else does-not. Vice-versa is also true.

4.1.6 Capacitor

A) INTRODUCTION

The function of capacitors is to store electricity, or electrical energy. The capacitor also functions as filter, passing AC, and blocking DC. The capacitor is constructed with two electrode plates

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separated by insulator. They are also used in timing circuits because it takes time for a capacitor to fill with charge. They can be used to smooth varying DC supplies by acting as reservoir of charge.

The capacitor's function is to store electricity, or electrical energy. The capacitor also functions as

a filter, passing alternating current (AC), and blocking direct current (DC). This symbol ( )is

used to indicate a capacitor in a circuit diagram. The capacitor is constructed with two electrode

plates facing each other but separated by an insulator.

When DC voltage is applied to the capacitor, an electric charge is stored on each electrode. While

the capacitor is charging up, current flows. The current will stop flowing when the capacitor has

fully charged.

Commercial capacitors are generally classified according to the dielectric. The most used are

mica, paper, electrolytic and ceramic capacitors. Electrolytic capacitors use a molecular thin

oxide film as the dielectric resulting in large capacitance values. There is no required polarity,

since either side can be the most positive plate, except for electrolytic capacitors. These are

marked to indicate which side must be positive to maintain the internal electrolytic action that

produces the dielectric required to form the capacitance. It should be noted that the polarity of the

charging source determines the polarity of the changing source determines the polarity of the

capacitor voltage.

B) BREAKDOWN VOLTAGE

When using a capacitor, you must pay attention to the maximum voltage which can be used. This

is the "breakdown voltage." The breakdown voltage depends on the kind of capacitor being used.

You must be especially careful with electrolytic capacitors because the breakdown voltage is

comparatively low. The breakdown voltage of electrolytic capacitors is displayed as Working

Voltage.

The breakdown voltage is the voltage that when exceeded will cause the dielectric (insulator)

inside the capacitor to break down and conduct. When this happens, the failure can be

catastrophic.

Types of Capacitors

There are various types of capacitors available in the market. Some of them are as follows:

Mica Capacitor

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Paper Capacitor

Ceramic Capacitor

Variable Capacitor

Electrolytic Capacitor

Tantalum Capacitor

Film Capacitor

Here we used only two types of capacitor i.e. ceramic capacitor & electrolytic capacitor.

1. Polarized capacitors

2. Un-polarized capacitors

C) POLARIZED CAPACITORS:

These are the capacitors having polarity. Basically these are of larger values than 1uf. For example

below is the diagram of capacitor of 220 microfarad and having breakdown voltage 25V.

Electrolytic capacitors are polarized and they must be connected the correct way round at least

one of their leads will be marked + or -. They are not damaged by heat when soldering.

Fig.4.1.10 polarized Capacitor

There are two designs of electrolytic capacitors; axial where the leads are attached to each end

(220µF in picture) and radial where both leads are at the same end (10µF in picture). Radial

capacitors tend to be a little smaller and they stand upright on the circuit board.

It is easy to find the value of electrolytic capacitors because they are clearly printed with their

capacitance and voltage rating. The voltage rating can be quite low (6V for example) and it

should always be checked when selecting an electrolytic capacitor. If the project parts list does

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not specify a voltage, choose a capacitor with a rating which is greater than the project's power

supply voltage. 25V is a sensible minimum for most battery circuits.

D) UN-POLARIZED CAPACITORS (SMALL VALUES, UP TO 1ΜF)

Small value capacitors are un-polarized and may be connected either way round. They are not

damaged by heat when soldering, except for one unusual type (polystyrene). They have high

voltage ratings of at least 50V, usually 250V or so. It can be difficult to find the values of these

small capacitors because there are many types of them and several different labeling systems.

Fig.4.1.11 Un-Polarized Capacitor

Many small value capacitors have their value printed but without a multiplier, so you need to use

experience to work out what the multiplier should be.

For example 0.1 means 0.1µF = 100nF.

Sometimes the multiplier is used in place of the decimal point:

For example: 4n7 means 4.7nF.

E) VARIABLE CAPACITORS

Variable capacitors are mostly used in radio tuning circuits and they are sometimes called 'tuning

capacitors'. They have very small capacitance values, typically between 100pF and 500pF

(100pF = 0.0001µF).

Fig4.1.12 Variable Capacitor

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Many variable capacitors have very short spindles which are not suitable for the standard knobs used

for variable resistors and rotary switches. It would be wise to check that a suitable knob is available

before ordering a variable capacitor.

F) METHODS OF MAKING CAPACITORS:

One way of making capacitors is to use the two poly-silicon layers in our process. We create a

parallel plate capacitor with poly1 and poly2 (“electrode”) forming the two parallel sides. The

silicon dioxide between the two poly layers is thin enough to yield good capacitance values per

unit area. This is called a poly-poly capacitor.

The other way would be to use the gate oxide and actually build a transistor whose gate area (W

x L) would actually give us the capacitance. These are called MOS capacitors, and they only

work properly when the transistor is strongly inverted or depleted. Otherwise, the capacitance

can vary with the voltage across it.

4.1.7 Diode Bridge

A) INTRODUCTION:

A diode bridge is an arrangement of four (or more) diodes in a bridge circuit configuration

that provides the same polarity of output for either polarity of input. When used in its most

common application, for conversion of an alternating current (AC) input into a direct

current (DC) output, it is known as a bridge rectifier. A bridge rectifier provides full-wave

rectification from a two-wire AC input, resulting in lower cost and weight as compared to a

rectifier with a 3-wire input from a transformer with a center-tapped secondary winding

Fig.4.1.13 Diode Bridge

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The essential feature of a diode bridge is that the polarity of the output is the same regardless

of the polarity at the input. The diode bridge circuit is also known as the Graetz circuit after

its inventor, physicist Leo Graetz.

B) BASIC OPERATION:

According to the conventional model of current flow originally established by Benjamin

Franklin and still followed by most engineers today, current is assumed to flow

through electrical conductors from the positive to the negative pole. In actuality, free

electrons in a conductor nearly always flow from the negative to the positive pole. In the vast

majority of applications, however, the actual direction of current flow is irrelevant. Therefore,

in the discussion below the conventional model is retained.

In the diagrams below, when the input connected to the left corner of the diamond is  positive,

and the input connected to the right corner is negative, current flows from the upper supply

terminal to the right along the red (positive) path to the output, and returns to the lower

supply terminal via the blue (negative) path.

Fig.4.1.14 Circuit Diagram Of Diode Bridge

In each case, the upper right output remains positive and lower right output negative. Since

this is true whether the input is AC or DC, this circuit not only produces a DC output from an

AC input, it can also provide what is sometimes called "reverse polarity protection". 

C) RECTIFIERS

A rectifier is an electrical device that converts alternating current (AC), which periodically

reverses direction, to direct current (DC), which flows in only one direction. The process is

known as rectification.

The simple process of rectification produces a type of DC characterized by pulsating voltages

and currents (although still unidirectional)

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HALF WAVE RECTIFICATION: In half wave rectification of a single-phase supply,

either the positive or negative half of the AC wave is passed, while the other half is blocked.

Because only one half of the input waveform reaches the output, mean voltage is lower. Half-

wave rectification requires a single diode in a single-phase supply, or three in a three-phase

supply. Rectifiers yield a unidirectional but pulsating direct current; half-wave rectifiers

produce far more ripple than full-wave rectifiers, and much more filtering is needed to

eliminate harmonics of the AC frequency from the output.

Fig.4.1.15 Half Wave Rectifier circuit

FULL WAVE RECTIFIER: A full-wave rectifier converts the whole of the input

waveform to one of constant polarity (positive or negative) at its output. Full-wave

rectification converts both polarities of the input waveform to DC (direct current), and yields

a higher mean output voltage. Two diodes and a center tapped transformer, or four diodes in

a bridge configuration and any AC source (including a transformer without center tap), are

needed. Single semiconductor diodes, double diodes with common cathode or common

anode, and four-diode bridges, are manufactured as single components.

Fig.4.1.16 Full Wave Rectifier Circuit

BRIDGE RECTIFIER: A bridge rectifier makes use of four diodes in a bridge arrangement

to achieve full-wave rectification. This is a widely used configuration, both with individual

diodes wired as shown and with single component bridges where the diode bridge is wired

internally.

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Fig. 4.1.17 Bridge Rectifier circuit

D) CURRENT FLOW IN BRIDGE RECTIFIER

Fig. 4.1.18 Current Flow In Bridge Rectifier

4.1.8 16x2 Lcd

A) INTRODUCTION:

LCD (Liquid Crystal Display) screen is an electronic display module and find a wide range of

applications. A 16x2 LCD display is very basic module and is very commonly used in

various devices and circuits. These modules are preferred over seven segments and other

multi segment LEDs. The reasons being: LCDs are economical; easily programmable; have

no limitation of displaying special & even custom characters (unlike in seven segments),

animations and so on.

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A 16x2 LCD means it can display 16 characters per line and there are 2 such lines. In this

LCD each character is displayed in 5x7 pixel matrix. This LCD has two registers, namely,

Command and Data. The command register stores the command instructions given to the

LCD. A command is an instruction given to LCD to do a predefined task like initializing it,

clearing its screen, setting the cursor position, controlling display etc. The data register stores

the data to be displayed on the LCD. The data is the ASCII value of the character to be

displayed on the LCD.

Features:-

5 x 8 dots with cursor

Built-in controller (KS 066 or Equivalent)

+ 5V power supply (Also available for + 3V)

1/16 duty cycle

B/L to be driven by pin 1, pin 2 or pin 15, pin 16 or A.K (LED)

N.V. optional for + 3V power supply.

B) PIN DESCRIPTION:

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C) LCD INTERFACE DIAGRAM:

Below is the connection diagram of LCD in 4-bit mode, where we only need 6 pins to interface an LCD. D4-D7 is the data pins connection and Enable and Register select are for LCD control pins. We are not using Read/Write (RW) Pin of the LCD, as we are only writing on the LCD so we have made it grounded permanently. If you want to use it, then you may connect it on your controller but that will only increase another pin and does not make any big difference. Potentiometer RV1 is used to control the LCD contrast. The unwanted data pins of LCD i.e. D0-D3 are connected to ground.

Fig 4.1.19 Lcd Interfacing

4.1.9 Voltage Regulator

A) INTRODUCTION:

A voltage regulator is designed to automatically maintain a constant voltage level. A voltage

regulator may be a simple "feed-forward" design or may include negative feedback control

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loops. It may use an electromechanical mechanism, or electronic components. Depending on

the design, it may be used to regulate one or more AC or DC voltages.

Electronic voltage regulators are found in devices such as computer power supplies where

they stabilize the DC voltages used by the processor and other elements. In

automobile alternators and central power station generator plants, voltage regulators control

the output of the plant. In an electric power distribution system, voltage regulators may be

installed at a substation or along distribution lines so that all customers receive steady voltage

independent of how much power is drawn from the line.

Fig.4.1.20 Voltage Regulator

Voltage regulator ICs are available with fixed (typically 5, 12 and 15V) or variable output

voltages. The maximum current they can pass also rates them. Negative voltage regulators

are available, mainly for use in dual supplies. Most regulators include some automatic

protection from excessive current (over load protection) and over-heating (thermal

protection). Many of fixed voltage regulator ICs has 3 leads. They include a hole for

attaching a heat sink if necessary.

B) PIN ARCHITECTURE:

7805, It is a voltage regulator the 78 indicates a positive regulator the 05 indicates the voltage

output. At 1 amp if adequate heats sink is provided. Never fear it has thermal protection to

shut it down only if the internal heating exceeds the safety zone. It will not destroy itself by

removing or reducing the load it will come- back alive after cooling

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Fig.4.1.21 Pin Diagram Of Voltage Regulator

C) INTERNAL BLOCK DIAGRAM:

Fig4.1.22 Internal Block Diagram Of Voltage Regulator

4.1.10Resistance

A) INTRODUCTION:

There is always some resistance in every circuit.

• A circuit is always made up of some wire, so there will be some resistance there.

• Even the battery has parts that offer resistance to the flow of electrons.

• The only circuits that come near to zero resistance are superconductors.

• This resistance that is from the parts of the circuit itself (especially the battery) is called

internal resistance.

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• A resistor is a device found in circuits that has a certain amount of resistance. Why would

you ever want to add resistance to a circuit by using a resistor?

• The most common reason is that we need to be able to adjust the current flowing through a

particular part of the circuit.

• If voltage is constant, then we can change the resistor to change the current. I=V R If “V” is

constant and we change “R”, “I” will be different.

B) ACTUAL RESISTORS:

The Example 1: What is the resistance of this resistor?

Fig 4.1.23 Resistor

Notice that the colours on this resistor are (in order) Red, Green, Orange, and Silver.

1. The first line is the first digit → Red = 2

2. The second line is the second digit → Green = 5

3. The third line is the multiplier → Orange = 103

4. The last line (if any) is the tolerance → Silver = } 10%�So the final answer would be 25 x 103 Ω ± 10%

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4.1.11 LED

A) INTRODUCTION:

A light-emitting diode (LED) is a semiconductor light source. LEDs are used as indicator lamps in many devices and are increasingly used for other lighting. Appearing as practical electronic components early LEDs emitted low-intensity red light, but modern versions are available across the visible, ultraviolet, and infrared wavelengths, with very high brightness.

Fig4.1.24 LED & Symbol of LED

When a light-emitting diode is forward-biased (switched on), 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 colour of the light (corresponding to the energy of the photon) is determined by the energy gap of the semiconductor. A LED is often small in area (less than 1 mm2), and integrated optical components may be used to shape its radiation pattern. LEDs present many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. LEDs powerful enough for room lighting are relatively expensive and require more precise current and heat management than compact fluorescent lamp sources of comparable output.

TYPE Passive opto-electronic device

Working principle Electroluminescence

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4.2 Software Components

4.2.1 ARDUINO COMPILER:

The Arduino IDE is a cross-platform application written in Java, and is derived from the IDE for the Processing programming language and the Wiring project. It is designed to introduce programming to artists and other newcomers unfamiliar with software development. It includes a code editor with features such as syntax highlighting, brace matching, and automatic indentation, and is also capable of compiling and uploading programs to the board with a single click. There is typically no need to edit make files or run programs on a command-line interface. Although building on command-line is possible if required with some third-party tools such as Ino.

Fig4.2.1 Screen Sort Of Arduino Compiler

The Arduino IDE comes with a C/C++ library called "Wiring" (from the project of the same name), which makes many common input/output operations much easier. Arduino programs are written in C/C++.

4.2.2 DOCKLIGHT:

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Docklight is a testing, analysis and simulation tool for serial communication protocols (RS232, RS485/422 and others). It allows you to monitor the communication between two serial devices or to test the serial communication of a single device. Docklight significantly increases productivity in a broad range of industries, including automation and control, communications, automotive, equipment manufacturers, and embedded / consumer products. Docklight is easy to use and runs on almost any standard PC using Windows 8, Windows 7, Windows Vista or Windows XP operating system.

Fig 4.2.2 Docklight screen sort

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5 Coding

void setup(){pinMode(led_pin,OUTPUT);pinMode(buzz_pin,OUTPUT);pinMode(18,INPUT);digitalWrite(18,HIGH);lcd.begin(16, 2);lcd.print("GSM Based System");byte s=search_modem(); // search for modem to be connected.blockings=configure_modem(); // configure the modems=del_sms(); // keep the location 1 clear.lcd.clear();lcd.print("GSM Based System");indicate(100);if(EEPROM.read(0)!=0) // if not registered yet then thedefault number should be...{Serial.println("Number not registered yet");EEPROM.write(1,'9'); //default numberEEPROM.write(2,'6');EEPROM.write(3,'9');EEPROM.write(4,'6');EEPROM.write(5,'3');EEPROM.write(6,'6');EEPROM.write(7,'4');EEPROM.write(8,'9');EEPROM.write(9,'0');EEPROM.write(10,'5');}}//*******************************************void loop(){// loop_check();if(gsm.available()>2)

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{indicate(1000);int k=check_sms();if(k==1)k=read_sms();if(k==1)k=del_sms(); // clear the location for next sms toarrive}if(analogRead(2)>500){sms2send="Some one inside the bank";send_sms();indicate(10000);lcd.clear();

lcd.print("Alarm");while(1); // hold here the system}// Serial.print("FREE RAM :");// Serial.println(memoryFree());}byte search_modem() // will keep on searching for modemunless it is found{Serial.println("Searching the Modem");lcd.clear();lcd.print(" Testing modem....");lcd.setCursor(0,1);char ch[50];int n=0;gsm.println("AT"); // activate the modemwhile(1){if(gsm.available()){ch[n]=gsm.read();if((ch[n-1]=='O')&&(ch[n]=='K')) //ok if modem is there{lcd.print("Testing Done...");return 1;}n++;}else{lcd.clear();lcd.print("Connect Modem");lcd.setCursor(0,1);gsm.println("AT"); // activate the modem}

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}}// search endsbyte configure_modem(){char ch[50];int n=0;lcd.clear();lcd.print("Configuring Modem....");gsm.println("ATE0"); // turn off echodelay(100);gsm.println("AT+CMGF=1"); //set the sms format as textdelay(100);gsm.println("AT+CNMI=2,1,0,0,1"); // indicates the arrivalof smsdelay(1000);gsm.flush();gsm.println("AT");while(1){

if(gsm.available()){ch[n]=gsm.read();if((ch[n-1]=='O')&&(ch[n]=='K')) //ok if modem is there{lcd.clear();lcd.print("Cofigured.....");return 1;}n++;}else{n=0;lcd.clear();lcd.print("Confi Failed..");lcd.setCursor(0,1);lcd.print("Please Reset");}}}int check_sms(){ Serial.println("check sms");char ch[20];int n=0;byte flag=0; // indicates the arrival of smsif(gsm.available()){delay(1000);// wait for all serial data to arrive.while(gsm.available()) // read all serial data.

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{ch[n]=gsm.read();if((ch[n-3]=='C')&&(ch[n-2]=='M')&&(ch[n-1]=='T')&&(ch[n]=='I')){flag=1;lcd.clear();lcd.print("SMS Arrived");}n++;}if(flag==1)return 1;else{gsm.flush();return 0;}}}byte read_sms(){Serial.println("read sms");char ch[100];

int n=0;int m=0;int digit=0;byte temp=0;// to read the smsbyte temp1=0; // to read the mobile numberlcd.clear();lcd.print("Reading SMS....");lcd.setCursor(0,1);gsm.println("AT+CMGR=1"); // command to read the sms atloction 1while(1){if(gsm.available()){ch[n]=gsm.read();Serial.print(ch[n]);if((ch[n-1]=='O')&&(ch[n]=='K')) // successful readingof SMS{for(int i=0;i<=n;i++) // extract sms part{if(temp1==2) // + sign arrives with second + sign{temp_mob[digit]=ch[i+2]; // digits after +91digit++;

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if(digit==10)temp1=0; // reading of mobile number finished}if(ch[i]=='*') // terminating character stopreading{temp=0;sms_length=m-1;}if(temp==1) // store sms part in sms variable{sms[m]=ch[i];m++;}if(ch[i]=='#') //starting character start readingtemp=1;if(ch[i]=='+')// mobile number starts with +91temp1++;}// end of for loopSerial.print("mobile number ");for(int i=0;i<=9;i++){Serial.print(char(temp_mob[i]));}register_user(); //function to register the user.lcd.print("Reading Successful..");return 1;}

n++;}}}byte del_sms(){ Serial.println("del sms");char ch[10];int n=0;lcd.clear();lcd.print("Removing SMS..");lcd.setCursor(0,1);gsm.println("AT+CMGD=1"); // command to delete the sms atloction 1while(1){if(gsm.available()){delay(1000);while(gsm.available()){ch[n]=gsm.read();

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if((ch[n-1]=='O')&&(ch[n]=='K')){lcd.print("SMS Deleted..");return 1;}n++;}lcd.print("Error...");return 0;}}}void loop_check(){if(Serial.available()){char ch=Serial.read();gsm.print(ch);}if(gsm.available()){char ch=gsm.read();Serial.print(ch);}}void indicate(int d){digitalWrite(buzz_pin,HIGH);digitalWrite(led_pin,HIGH);delay(d);digitalWrite(buzz_pin,LOW);digitalWrite(led_pin,LOW);}

int register_user() // register user{ Serial.println("register ");Serial.print("sms");Serial.println(sms);if((sms[0]=='A')&&(sms[1]=='B')&&(sms[2]=='C')){lcd.clear();lcd.println("Registration....");EEPROM.write(0,0); // to indicate that the user has beenregistereddelay(100);EEPROM.write(1,sms[3]);delay(100);EEPROM.write(2,sms[4]);delay(100);EEPROM.write(3,sms[5]);

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delay(100);EEPROM.write(4,sms[6]);delay(100);EEPROM.write(5,sms[7]);delay(100);EEPROM.write(6,sms[8]);delay(100);EEPROM.write(7,sms[9]);delay(100);EEPROM.write(8,sms[10]);delay(100);EEPROM.write(9,sms[11]);delay(100);EEPROM.write(10,sms[12]);delay(100);sms2send="This number is registered";send_sms();}else{lcd.clear();lcd.print("Invalid Password");}}byte send_sms(){ Serial.println("sending sms");char ch[20];int n=0;byte number=0;lcd.clear();lcd.print("Sending SMS..");lcd.setCursor(0,1);gsm.print("AT+CMGS=");delay(100);gsm.print(34,BYTE);number=EEPROM.read(1); // first digit of the mobile numberlcd.print(char(number));gsm.print(number);

delay(10);number=EEPROM.read(2); // second digit of the mobilenumbergsm.print(number);lcd.print(char(number));delay(10);number=EEPROM.read(3);lcd.print(char(number));gsm.print(number);delay(10);number=EEPROM.read(4);

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lcd.print(char(number));gsm.print(number);delay(10);number=EEPROM.read(5);lcd.print(char(number));gsm.print(number);delay(10);number=EEPROM.read(6);lcd.print(char(number));gsm.print(number);delay(10);number=EEPROM.read(7);lcd.print(char(number));gsm.print(number);delay(10);number=EEPROM.read(8);lcd.print(char(number));gsm.print(number);delay(10);number=EEPROM.read(9);lcd.print(char(number));gsm.print(number);delay(10);number=EEPROM.read(10); // 10th digit of the mobile numbergsm.print(number);lcd.print(char(number));gsm.println(34,BYTE);delay(100);gsm.println(sms2send);delay(1000);gsm.print(char(26)); // ascii code for ctrl^zwhile(1){if(gsm.available()){ch[n]=gsm.read();Serial.print(char(ch[n]));if((ch[n-3]=='C')&&(ch[n-2]=='M')&&(ch[n-1]=='G')&&(ch[n]=='S')){lcd.print("Sent");delay(1000);gsm.flush();// clear all other datareturn 1;}

if((ch[n-3]=='E')&&(ch[n-2]=='R')&&(ch[n-1]=='R')&&(ch[n]=='O')){lcd.print("Error");

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delay(1000);gsm.flush();// clear all other datareturn 0;}n++;}}}int memoryFree(){extern int __bss_end;extern void *__brkval;int freeValue;if((int)__brkval == 0)freeValue = ((int)&freeValue) - ((int)&__bss_end);elsefreeValue = ((int)&freeValue) - ((int)__brkval);return freeValue;}

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6 Component Layout

Fig 6.1 Layout Of Components

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7 PCB Layout

Fig7.1 PCB Layout

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8 Working

The 12 V DC is fed to 7805 regulator to fetch +5v regulated output. This regulated voltage is given to all the components to function properly. However, the modem power supply is +12V.

This project is based on GSM Modem 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. The format for sending message is (#India*) 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. On the basis of proper initiator and terminator the controller (ATMEGA168) decodes the SMS (#&* in our case).The GSM modem can be configured for sending and SMS also by configuring it using proper AT command (refer programming). This feature of the modem has been used in this project.

Secondly, there is intruder detection system designed to check the presence of any person. The PIR is used for this purpose. This sensor is capable of detecting any moving particle. Now, according to the amount of moving particle this sensor gives an analog variation of voltage on its data pin. The SMS will be sent to the authorized mobile. The SMS will be predefined text. The outputs through the microcontroller in this project are proper display on LCD of presence and absence and SMS sent notification. Proper LCD display is ensured through programming and the LCD interface design. If some intruder is detected pre-defined SMS will be sent to the authorized mobile using the GSM communication through the GSM modem that has been configured to send the SMS and the controller will blow an alarm through the buzzer. All the configuration commands of GSM modem (AT commands), authorized mobile number to receive SMS (at remote location)and controlling is done through the controller programming means controller controls all this process as per the program.

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9 Testing

1. Connect the black terminal of the Digital Multimeter to the ground of the supply source and turn the knob to 20V DC voltage.

2. Make sure the notch of all the IC’s including microcontroller is same as given above.

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3. Check the continuity and short circuit of the PCB's.

4. Check the voltages at pin o (output) of all the three 7805 and it should be +5 volts.

5. Check the voltage at pin 7 and 20 of the microcontroller it should be +5 volts.

6. Check the voltage at data pin of the PIR sensor it should be vary according to human body or any moving particle.

7. Check the GSM Modem and see RX and TX.

8. Connect to TX of PCB with RX of GSM Modem.

9. Connect to RX of PCB with TX of GSM Modem.

10. Check the voltage at pin 2 and pin 15 of the LCD, It should be +5V

11. LCD should display all the messages.

12. If all the above parameters are met, then the testing part is complete and we can run our Project. Caution: Check the orientation of LCD, and all IC.

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10 Advantage

1) Less costly.

2) System can be easily constructed.

3) No man power required for operation.

4) Provide high security.

5) Ease deployment is due to wireless mode of communication. GSM technology provides the benefit that the system is accessible in remote areas as well.

6) The user can get alert anywhere through the GSM technology thus making the system location independent.

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11 Application

1) This project has its main application in security system and it can be used in homes as SMS based domestic security system.

2) Motion detection based system like door control , light control, etc.

3) This system can also be used in industries as a GSM based industrial security system

4) It can also be used in hospital but we need to do a little bit modification for use in hospital. We can add oxygen gas sensor to detect the leakage in oxygen gas cylinder as it can also cause fire.

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12 Conclusion

After the successful working of the project, it can be concluded that this project is suitable for easily security system there can be further upgradations in the project which could led to a much better for a security system.

Some of the possible ways are as follows:

1) Voice announcement system can be added to indicate device condition we can added voice announcement system along with the buzzer of if there are hazardous parameter detected then respective voice message will be announced

2) We can add finger print sensor instead of password based door operating so entry will be allowed for the authorized person using their finger print

3) We can monitor and control more parameter and device .we can implement other modules like fire sensor and wind sensor.

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13 Reference

1) www.wikipedia.com

2) www.circuitstoday.com

3) www.electroschematic.com

4) www.efy.com

5) www.vegakitindia.com

6) “Electronics For You” Magazine

7) Metha V.K. “principle Of Electronics” [Book]

8) Kumar N. Suresh “Electronics devices and circuit”[Book]

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