DedicationWe dedicate our project to our Supervisor for his support and guidance that lead us to

fulfill our project. Than we dedicate our project to our parents who supported us

throughout our Educational career financially and morally.

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ACKNOWLEDGMENT

We place on record and warmly acknowledge the continuous encouragement,

invaluablesupervision, timely suggestions and inspired guidance offered by our guide

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ABSTRACT

Notice Board is primary thing in any institution / organization or public utility places

like bus stations, railway stations and parks. But sticking various notices day-to-day is

a difficult process. This project deals with an advanced notice board. This notice

board will display time temperature on the 20x4 lcd. The bluetooth technology is also

used in this project. Further development to this project can be done by providing

message storage facility by non-volatile memory i.e. EEPROM attached to the

microcontroller for retrieval of old messages if required. It can also be expanded to a

bigger LCD screen.

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TABLE OF CONTENTSACKNOWLEDGMENT.......................................................................2TABLE OF CONTENTS......................................................................4LIST OF ACRONYMS........................................................................5Chapter 1...............................................................................................6INTRODUCTION................................................................................61.1 Overview......................................................................................................7

1.2 Aim of the project........................................................................................7

1.3 Electronic Notice board......................................................................................7

1.4 Components........................................................................................................8

1.5 Advantages.........................................................................................................8

1.7 Goal....................................................................................................................8

LIERATURE REVIEW........................................................................92.1 Broadcasting.......................................................................................................9

2.2 Notice board.....................................................................................................10

2.3 Related Work....................................................................................................10

2.4 Bluetooth technology.......................................................................................11

2.4 Real time clock.................................................................................................13

METHODOLOGIES AND IMPLEMENTATION............................143.1 Interfacing 20x4 Lcd with arduino...................................................................14

Step 1: Material Required......................................................................................15

Chapter 4.............................................................................................18TOOLS AND TECHNIQUES............................................................184.1Crystal Oscillator..............................................................................................18

4.2 Arduino............................................................................................................21

4.3 Capacitor..........................................................................................................25

4.4 Resistor.............................................................................................................29

4.5 LM35................................................................................................................30

4.6 7805 IC............................................................................................................33

7805 IC working...................................................................................36

4.7 LCD..................................................................................................................37

4.8 Serial Port Bluetooth Module (Master/Slave) : HC-05...................................39

HC-05 zs-040 Status LED..............................................................................40

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Connections.......................................................................................................40

Default Settings................................................................................................41

Pair with an Android device.........................................................................41

Hardware Features......................................................................................42

Software Features.......................................................................................42

CONCLUSION...................................................................................43REFRENCES......................................................................................44

.

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LIST OF ACRONYMS

LCD Liquid crystel display

DAC Digital to analog convertor

DAQ Data Acquisition

USB Universal Serial Bus

PWM Pulse Width Modulation

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Chapter 1

INTRODUCTIONPresently almost all electronic notice boards are designed using wired system.One of

the drawbacks of the design is the system is inflexible in term of placement. The

commonnotice board cannot be placed anywhere because of the messy wire. The aim

of this project is to develop a wireless notice board that will be used atthe faculty in

order to display latest information.             

This wireless notice board project mainly focuses on transmission of textual data

through asynchronous serial communication. The data will be processed by the

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microcontroller on both ends. The data will be displayed on LCD only after entering

unique pass key.

In this project we not only send the data but send the data with pass code also. Which

enables us to prevent the unauthorized use of LCD display board and only the person

who have pass code can have access to LCD board .

1.1 OverviewThe Electronic Notice board is aimed at the colleges and universities for displaying

day-to-day information continuously or at regular intervals during the working hours.

it offers flexibility to display flash news or announcements faster than the

programmable system.

Now-a-days advertisement is going digital. The big shops and the shopping centers

use digital displays now. Also, in trains and buses the information like platform

number, ticket information is displayed in digital boards. People are now adapted to

the idea of the world at its finger-tips.

1.2 Aim of the projectThe aim of this project to design such project in which we do not need to write notice

on the notice board. We simply send message from the mobile through infrared

system. Also we have real time display through which we can display time on the lcd

and can easily change this time.

1.3 Electronic Notice boardThis is an embedded based project. An embedded system is a combination of

hardware and software and perhaps other mechanical parts designed to perform a

specific function. A Notice Board is a very essential device in any institution /

organization or public utility place like bus stations, railway stations and parks.

It is further displayed on an electronic notice board which equipped with LCD display

interfaced to microprocessor powered by a regulated power supply from mains

supply. This project is our experiment on real time noticing.

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1.4 ComponentsComponents essential for the working of project are:

1.) Temperatue

2.) Bluetooth module

3.) Power Supply

4.) LCD

5.) Microcontroller

6.) Resistor

7.) Voltage Regulators

We shall discuss these components in detail.

1.5 AdvantagesA lot of interaction and information sharing occurs. No printing & photocopying

costs. No manual effort. Helps to retain and develop the knowledge base of your

college or office. Saves Time, Energy and finally Environment.

1.7 GoalAt present, when information has to be updated in a notice board, it has to be done

manually. So the goal of our project is to display notices and articles quickly and

automaticly.

Chapter 2

LIERATURE REVIEW

2.1 BroadcastingToday, interaction with digital displays is a deskbound or device-dependent

experience. However, developments in display and information sharing technologies

may enable a new form of interaction with digital media: ‘ubiquitous computing’. In

ubiquitous computing, the physical location of data and processing power is not

apparent to the user. Rather, information is made available to the user in a transparent

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and contextually relevant manner. A single display device restricts the repertoire of

interactions between the user and digital media, so ubiquitous computing requires

displays wherever the user might need one – in appliances, tabletops public transport,

walls, etc.

It is thereby a modest effort to realize the complete potential of public display boards

in instantaneous information broadcast in swift response to events of interests.

2.2 Notice boardA Notice Board is a place where people can leave public messages, for example, to

advertise things, announce events, or provide information . Notice boards are often

made of a material such as cork to facilitate addition and removal of paper messages

or it can be placed on digital devices such as computers, phones . So people can leave

and erase messages for other people to read and see. The main aim of this paper is to

make information dissemination much easier in a paperless community as the world

tends to graduate into that line of interaction to develop the Notice Board facility as

an application, for use in college administration. This paper is about the

implementation of Electronic notice board to the college administration system. The

campus in focus is all the professional colleges which includes various departmental

notice boards as well as other related notice boards. This work generally intends to act

as a support system for the existing method by which notices are being posted .

The notice board is a flat solid object placed at strategic positions making it an object

on which notices and articles are being placed. In the professional college campus,

notices spring up from different officers bringing reminders, warnings, advice, results,

and appointments to be placed on the notice board. As these notices are being placed

on the boards, some of the old notices are not removed and with time the notice

boards get filled up with relevant and irrelevant notice messages, as a result of this, a

person might not take caution of any new notice being displayed

2.3 Related WorkComing across a brief case study of the professional college, where information is a

vital key for everybody’s progress in and around the campus. The existing notice

board system that is applied in the college works on the basis of manual updating

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method. A person needs to have a tab about the regulation of these notices. Spaces

need to be searched in and around the notice board according to the notice that is to be

displayed. This can be a tedious job, especially on the day of exam we get to see a

huge crowd of students surrounding a single notice which includes the subject with

room number; this might also lead the student to panic at the last go to their exam.

Apart from that, at times the student would not know the updation that has occurred.

Regular viewing is needed if he/she wants to know about the events. But if the notice

board includes 20 plus notices being displayed at a time there are possibilities that

students may not come across all of it; might miss few of them. It’s impossible to

accommodate all the info within the main notice board, therefore chances of

displaying department related information in the departmental notice board is high,

which again might remain unaware from students notice. Moreover library related

information as well as placement department information shall be displayed only in

their respective notice boards, wherein the students hardly visit and being unaware of

important notices shall have to pay a huge penalty at the end. The absentees remain

unaware of the notice that was read during their absence. Also there are limitations on

space availability and time consuming, especially when it comes for searching for the

relevant notice. Maintaining the archived files becomes hectic. On Regular

observation only the updates will be available. Also cannot be accessible outside that

physical location.

2.4 Bluetooth technologyBluetooth is a wireless technology used to transfer data between different electronic

devices. The distance of data transmission is small in comparison to other modes of

wireless communication. This technology eradicates the use of cords, cables, adapters

and permits the electronic devices to communicate wirelessly among each other. 

 

The key features of Bluetooth technology:

·         Less complication

·         Less power consumption

·         Available at cheaper rates

·         Robustness

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Bluetooth technology permits hands free headset for incoming voice calls, ability of

printing and fax, and automatic synchronization of PDA. Click to now more about

basics of Bluetooth Protocol.

 

Classification

Various types of Bluetooth technology are available in the markets which help the

consumers to communicate wirelessly. The different types of Bluetooth devices are

PC cards, radios, dongles, and headsets. Laptops and other Internet enabled

equipments use Bluetooth technology such as wireless mouse and keyboard to

communicate wirelessly. Music players like iPods, music phones, or other MP3

players make use of stereo headphones.

Applications

The first and foremost application of Bluetooth technology would be to eradicate the

tangling of cables that would mess up the room.

1.      Bluetooth’s biggest contribution is to provide a phone with a headset that works

wirelessly. This is possible by providing the caller with an earpiece and a small

microphone attached to the caller’s shirt. The mobile phone can be located in a bag or

anywhere in the body. The caller can dial a number even without touching a button on

the mobile phone. This technology has the advantage of eliminating the radiation

hitting the cerebral region.

2.      PDA, PC or laptop which has enabled Bluetooth can communicate with each

other and update with its latest information. This technology has helped in

synchronizing the data easily.

 

3.      It is difficult to send emails while travelling in a flight. On landing of the flight,

the Bluetooth enabled laptop can send the email only when it gets in touch with the

user’s phone.

 

4.      Wireless mouse and keyboards are introduced.

 

5.      One will be alerted on his/her mobile phone when your laptop receives the mail.

 

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6.   You can try to locate a printer via laptop. You will get the printout of that

document once that printer is located.

2.4 Real time clock

A real-time clock (RTC) is a computer clock (most often in the form of an integrated

circuit) that keeps track of the current time.

Although the term often refers to the devices in personal

computers, servers and embedded systems, RTCs are present in almost any electronic

device which needs to keep accurate time.

The term is used to avoid confusion with ordinary hardware clocks which are

only signals that govern digital electronics, and do not count time in human units.

RTC should not be confused with real-time computing, which shares its three-letter

acronym but does not directly relate to time of day.

Purpose

Although keeping time can be done without an RTC, using one has benefits:

Low power consumption[2] (important when running from alternate power)

Frees the main system for time-critical tasks

Sometimes more accurate than other methods

A GPS receiver can shorten its startup time by comparing the current time, according

to its RTC, with the time at which it last had a valid signal.  If it has been less than a

few hours, then the previous ephemeris is still usable.

Power source

RTCs often have an alternate source of power, so they can continue to keep time

while the primary source of power is off or unavailable. This alternate source of

power is normally a lithium battery in older systems, but some newer systems use

a supercapacitor, because they are rechargeable and can be soldered. The alternate

power source can also supply power to battery backed RAM.

Timing

Most RTCs use a crystal oscillator, but some use the power line frequency. In many

cases, the oscillator's frequency is 32.768 kHz This is the same frequency used

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inquartz clocks and watches, and for the same reasons, namely that the frequency is

exactly 215 cycles per second, which is a convenient rate to use with simple binary

counter circuits.

Chapter 3

METHODOLOGIES AND IMPLEMENTATION3.1 Interfacing 20x4 Lcd with arduino

A liquid-crystal display (LCD) is a flat panel display, electronic visual display, or

video display that uses the light modulating properties of liquid crystals. Liquid

crystals do not emit light directly.  In a monochromatic 20x4 alphanumeric LCD.

20x4 means that 20 characters can be displayed in each of the 4 rows of the 20x4

LCD, thus a total of 80 characters can be displayed at any instance of time.

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Step 1: Material Required

List of requirements is as follows:

1. Arduino/or any other clone

2. 20x4 LCD

3. Breadboard

4. 1k, 220R Resistors

5. Connecting wires

The LCD we are using has 16 pins. Description of each pin is as follows:

Pin No Symbol Level Description

1 VSS 0V Ground

2 VDD 5V Supply Voltage for logic

3 VO (Variable) Operating voltage for LCD

4 RS H/L H: DATA, L: Instruction code

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5 R/W H/L H: Read(MPU?Module) L: Write(MPU?Module)

6 EH H->L Chip enable signal

7 DB0 H/L Data bus line

8 DB1 H/L Data bus line

9 DB2 H/L Data bus line

10 DB3 H/L Data bus line

11 DB4 H/L Data bus line

12 DB5 H/L Data bus line

13 DB6 H/L Data bus line

14 DB7 H/L Data bus line

15 A 5V LED +

16 K 0V LED-

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1. Study the schematic carefully.

2. Place your LCD on the bread board.

3. Make connections as per the schematic.

4. Instead of the potentiometer, you can use a 1k resistor and connect Pin 3 of LCD to Vcc via the resistor.

5. Carefully check whether all the connections are tight and correct.

6. Power up your Arduino via USB and check whether the LCD lights up. If yes, proceed.

3.2 Interfacing bluetooth module with arduino

1) Arduino Board " I used Arduino Uno ".

2) Bluetooth module HC-05.

3)Solderless jumper.

4)Bread Board 

To make a link between your Arduino and bluetooth , do the following :

1) Go to the  bluetooth icon , right click and select Add a Device 

2) Search for new device , Our bluetooth module will appear as HC-05 , and add it 

3) The pairing code will be 1234 .

4)after make a pairing , we can now program the arduino and upload a sketch  to send or receive data from Computer.

As I mentioned before , I will use software serial library to make pin D10 & D11 As Tx & Rx instead of using the default Rx and tx " D0 &D1 On most arduino Board " .

this program below allow us to control LED connected to D13 To blink on/off , by press # 1 from PC Keyboard the LED blink on , and if we press 0 LED blink off ! 

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To send the Control commands from Computer to arduino , Go to the tera term , Run it , and choose Serial , and select the bluetooth Serial from the list as Shown on the picture .

The code below :

// This program shown how to control arduino from PC Via Bluetooth// Connect

// arduino>>bluetooth

// D11   >>>  Rx

// D10   >>>  Tx

#include <SoftwareSerial.h>// import the serial librarySoftwareSerial Genotronex(10, 11); // RX, TXint ledpin=13; // led on D13 will show blink on / offint BluetoothData; // the data given from Computer

void setup()

{  // put your setup code here, to run once:  Genotronex.begin(9600);

  Genotronex.println("Bluetooth On please press 1 or 0 blink LED ..");

 pinMode(ledpin,OUTPUT);

}

void loop()

{ // put your main code here, to run repeatedly:   if (Genotronex.available())

{BluetoothData=Genotronex.read();  if(BluetoothData=='1'){   // if number 1 pressed .   digitalWrite(ledpin,1);

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Genotronex.println("LED  On D13 ON ! ");

  } if (BluetoothData=='0'){// if number 0 pressed ....  digitalWrite(ledpin,0);

Genotronex.println("LED  On D13 Off ! ");

}}delay(100);// prepare for next data

}

Chapter 4

TOOLS AND TECHNIQUES.

4.1Crystal Oscillator A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a precise frequency. This frequency is commonly used to keep track of time, as inquartz wristwatches, to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for radio transmittersand receivers. The most common type of piezoelectric resonator used is the quartz crystal, so oscillator circuits incorporating them became known as crystal oscillators, but other piezoelectric materials including polycrystalline ceramics are used in similar circuits.

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Quartz crystals are manufactured for frequencies from a few tens of kilohertz to hundreds of megahertz. More than two billion crystals are manufactured annually. Most are used for consumer devices such as wristwatches, clocks, radios, computers, andcellphones. Quartz crystals are also found inside test and measurement equipment, such as counters, signal generators, andoscilloscopes.A crystal oscillator is an electronic oscillator circuit that uses a piezoelectric resonator, a crystal, as its frequency-determining element.Crystal is the common term used in electronics for the frequency-determining component, a wafer of quartz crystal or ceramic with electrodes connected to it. A more accurate term for it is piezoelectric resonator. Crystals are also used in other types of electronic circuits, such as crystal filters.Piezoelectric resonators, crystals are sold as separate components for use in crystal oscillator circuits, an example is shown in the picture. They are also often incorporated in a single package with the crystal oscillator circuit, shown on the righthand sideOperationA crystal is a solid in which the constituent atoms, molecules, or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions. Almost any object made of an elastic material could be used like a crystal, with appropriate transducers, since all objects have natural resonantfrequencies of vibration. For example, steel is very elastic and has a high speed of sound. It was often used

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in mechanical filters before quartz. The resonant frequency depends on size, shape, elasticity, and the speed of sound in the material. High-frequency crystals are typically cut in the shape of a simple, rectangular plate. Low-frequency crystals, such as those used in digital watches, are typically cut in the shape of a tuning fork. For applications not needing very precise timing, a low-cost ceramic resonator is often used in place of a quartz crystal.When a crystal of quartz is properly cut and mounted, it can be made to distort in an electric field by applying a voltage to an electrode near or on the crystal. This property is known as electrostriction or inverse piezoelectricity. When the field is removed, the quartz generates an electric field as it returns to its previous shape, and this can generate a voltage. The result is that a quartz crystal behaves like an RLC circuit, composed of aninductor, capacitor and resistor, with a precise resonant frequency.Quartz has the further advantage that its elastic constants and its size change in such a way that the frequency dependence on temperature can be very low. The specific characteristics depend on the mode of vibration and the angle at which the quartz is cut (relative to its crystallographic axes). Therefore, the resonant frequency of the plate, which depends on its size, does not change much. This means that a quartz clock, filter or oscillator remains accurate. For critical applications the quartz oscillator is mounted in a temperature-controlled container, called a crystal oven, and can also be mounted on shock absorbers to prevent perturbation by external mechanical vibrations.

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4.2 ArduinoArduino is an open-source platform used for building electronics projects. Arduino consists of both a physical programmable circuit board (often referred to as a microcontroller) and a piece ofsoftware, or IDE (Integrated Development Environment) that runs on your computer, used to write and upload computer code to the physical board.The Arduino platform has become quite popular with people just starting out with electronics, and for good reason. Unlike most previous programmable circuit boards, the Arduino does not need a separate piece of hardware (called a programmer) in order to load new code onto the board – you can simply use a USB cable. Additionally, the Arduino IDE uses a simplified version of C++, making it easier to learn to program. Finally, Arduino provides a

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standard form factor that breaks out the functions of the micro-controller into a more accessible package.

Arduino Uno R3 Front

The Arduino hardware and software was designed for artists, designers, hobbyists, hackers, newbies, and anyone interested in creating interactive objects or environments. Arduino can interact with buttons, LEDs, motors, speakers, GPS units, cameras, the internet, and even your smart-phone or your TV! This flexibility combined with the fact that the Arduino software is free, the hardware boards are pretty cheap, and both the software and hardware are easy to learn has led to a large community of users who have contributed code and released instructions for ahuge variety of Arduino-based projects.For everything from robots and a heating pad hand warming blanket to honest fortune-telling machines, and even a Dungeons and Dragons dice-throwing gauntlet, the Arduino can be used as the brains behind almost any electronics project.

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Arduino Uno R3 Back4.1.4.2 SummaryMicrocontroller ATmega328

Operating Voltage 5V

Input Voltage (recommended) 7-12V

Input Voltage (limits) 6-20V

Digital I/O Pins 14 (of which 6 provide PWM output)

Analog Input Pins 6

DC Current per I/O Pin 40 mA

DC Current for 3.3V Pin 50 mA

Flash Memory 32 KB (ATmega328) of which 0.5 KB used by bootloader

SRAM 2 KB (ATmega328)

EEPROM 1 KB (ATmega328)

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Power (USB / Barrel Jack)Every Arduino board needs a way to be connected to a power source. The Arduino UNO can be powered from a USB cable coming from your computer or a wall power supply (like this) that is terminated in a barrel jack. The USB connection is also how you will load code onto Arduino board. Do NOT use a power supply greater than 20 Volts as you will overpower (and thereby destroy) your Arduino. The recommended voltage for most Arduino models is between 6 and 12 Volts.

Pins (5V, 3.3V, GND, Analog, Digital, PWM, AREF)The pins on your Arduino are the places where you connect wires to construct a circuit (probably in conjuction with a breadboard and some wire. They usually have black plastic ‘headers’ that allow you to just plug a wire right into the board. The Arduino has several different kinds of pins, each of which is labeled on the board and used for different functions.GND Short for ‘Ground’. There are several GND pins on the Arduino, any of which can be used to ground your circuit.5V & 3.3V The 5V pin supplies 5 volts of power, and the 3.3V pin supplies 3.3 volts of power. Most of the simple components used with the Arduino run happily off of 5 or 3.3 volts.Analog The area of pins under the ‘Analog In’ label (A0 through A5 on the UNO) are Analog In pins. These pins can read the signal from an analog sensor (like a temperature sensor) and convert it into a digital value that we can read.

Digital

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Across from the analog pins are the digital pins (0 through 13 on the UNO). These pins can be used for both digital input (like telling if a button is pushed) and digital output (like powering an LED).PWM You may have noticed the tilde (~) next to some of the digital pins (3, 5, 6, 9, 10, and 11 on the UNO). These pins act as normal digital pins, but can also be used for something called Pulse-Width Modulation (PWM). We have a tutorial on PWM, but for now, think of these pins as being able to simulate analog output (like fading an LED in and out).AREF Stands for Analog Reference. Most of the time you can leave this pin alone. It is sometimes used to set an external reference voltage (between 0 and 5 Volts) as the upper limit for the analog input pins.Reset ButtonJust like the original Nintendo, the Arduino has a reset button (10). Pushing it will temporarily connect the reset pin to ground and restart any code that is loaded on the Arduino. This can be very useful if your code doesn’t repeat, but you want to test it multiple times. Unlike the original Nintendo however, blowing on the Arduino doesn’t usually fix any problems.Power LED IndicatorJust beneath and to the right of the word “UNO” on your circuit board, there’s a tiny LED next to the word ‘ON’ (11). This LED should light up whenever you plug your Arduino into a power source. If this light doesn’t turn on, there’s a good chance something is wrong. Time to re-check your circuit!TX RX LEDsTX is short for transmit, RX is short for receive. These markings appear quite a bit in electronics to indicate the pins responsible for serial communication. In our case, there are two places on the Arduino UNO where TX and RX appear – once by digital pins 0 and 1,

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and a second time next to the TX and RX indicator LEDs (12). These LEDs will give us some nice visual indications whenever our Arduino is receiving or transmitting data (like when we’re loading a new program onto the board).Main ICThe black thing with all the metal legs is an IC, or Integrated Circuit (13). Think of it as the brains of our Arduino. The main IC on the Arduino is slightly different from board type to board type, but is usually from the ATmega line of IC’s from the ATMEL company. This can be important, as you may need to know the IC type (along with your board type) before loading up a new program from the Arduino software. This information can usually be found in writing on the top side of the IC. If you want to know more about the difference between various IC’s, reading the datasheets is often a good idea.Voltage RegulatorThe voltage regulator (14) is not actually something you can (or should) interact with on the Arduino. But it is potentially useful to know that it is there and what it’s for. The voltage regulator does exactly what it says – it controls the amount of voltage that is let into the Arduino board. Think of it as a kind of gatekeeper; it will turn away an extra voltage that might harm the circuit. Of course, it has its limits, so don’t hook up your Arduino to anything greater than 20 volts.The Arduino FamilyArduino makes several different boards, each with different capabilities. In addition, part of being open source hardware means that others can modify and produce derivatives of Arduino boards that provide even more form factors and functionality. If you’re not sure which one is right for your project, check this guide for some helpful hints. Here are a few options that are well-suited to someone new to the world of Arduino.

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4.3 CapacitorThe Capacitor, sometimes referred to as a Condenser, is a simple passive device that is used to “store electricity”. The capacitor is a component which has the ability or “capacity” to store energy in the form of an electrical charge producing a potential difference (Static Voltage) across its plates, much like a small rechargeable battery. the Capacitor, sometimes referred to as a Condenser, is a simple passive device that is used to “store electricity”. The capacitor is a component which has the ability or “capacity” to store energy in the form of an electrical charge producing a potential difference (Static Voltage) across its plates, much like a small rechargeable battery. In its basic form, a Capacitor consists of two or more parallel conductive (metal) plates which are not connected or touching each other, but are electrically separated either by air or by some form of a good insulating material such as waxed paper, mica, ceramic, plastic or some form of a liquid gel as used in electrolytic capacitors. The insulating layer between a capacitors plates is commonly called the Dielectric.

Due to this insulating layer, DC current can not flow through the capacitor as it blocks it allowing instead a voltage to be present across the plates in the form of an electrical charge.The conductive metal plates of a capacitor can be either square, circular or rectangular, or they can be of a cylindrical or spherical shape with the general shape, size and construction of a parallel plate capacitor depending on its application and voltage rating.When used in a direct current or DC circuit, a capacitor charges up to its supply voltage but blocks the flow of current through it because the dielectric of a capacitor is non-conductive and basically

28

an insulator. However, when a capacitor is connected to an alternating current or AC circuit, the flow of the current appears to pass straight through the capacitor with little or no resistance.There are two types of electrical charge, positive charge in the form of Protons and negative charge in the form of Electrons. When a DC voltage is placed across a capacitor, the positive (+ve) charge quickly accumulates on one plate while a corresponding negative (-ve) charge accumulates on the other plate. For every particle of +ve charge that arrives at one plate a charge of the same sign will depart from the -ve plate.Then the plates remain charge neutral and a potential difference due to this charge is established between the two plates. Once the capacitor reaches its steady state condition an electrical current is unable to flow through the capacitor itself and around the circuit due to the insulating properties of the dielectric used to separate the plates.The flow of electrons onto the plates is known as the capacitors Charging Current which continues to flow until the voltage across both plates (and hence the capacitor) is equal to the applied voltageVc. At this point the capacitor is said to be “fully charged” with electrons. The strength or rate of this charging current is at its maximum value when the plates are fully discharged (initial condition) and slowly reduces in value to zero as the plates charge up to a potential difference across the capacitors plates equal to the source voltage.The amount of potential difference present across the capacitor depends upon how much charge was deposited onto the plates by the work being done by the source voltage and also by how much capacitance the capacitor has and this is illustrated below.Capacitor ConstructionThe parallel plate capacitor is the simplest form of capacitor. It can be constructed using two metal or metallised foil plates at a

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distance parallel to each other, with its capacitance value in Farads, being fixed by the surface area of the conductive plates and the distance of separation between them. Altering any two of these values alters the the value of its capacitance and this forms the basis of operation of the variable capacitors.Also, because capacitors store the energy of the electrons in the form of an electrical charge on the plates the larger the plates and/or smaller their separation the greater will be the charge that the capacitor holds for any given voltage across its plates. In other words, larger plates, smaller distance, more capacitance.By applying a voltage to a capacitor and measuring the charge on the plates, the ratio of the charge Qto the voltage V will give the capacitance value of the capacitor and is therefore given as: 

C = Q/Vthis equation can also be re-arranged to give the more familiar formula for the quantity of charge on the plates as:

Q = C x VAlthough we have said that the charge is stored on the plates of a capacitor, it is more correct to say that the energy within the charge is stored in an “electrostatic field” between the two plates. When an electric current flows into the capacitor, charging it up, the electrostatic field becomes more stronger as it stores more energy. Likewise, as the current flows out of the capacitor, discharging it, the potential difference between the two plates decreases and the electrostatic field decreases as the energy moves out of the plates.The property of a capacitor to store charge on its plates in the form of an electrostatic field is called the Capacitance of the capacitor. Not only that, but capacitance is also the property of a capacitor which resists the change of voltage across it.Voltage Rating of a CapacitorAll capacitors have a maximum voltage rating and when selecting a capacitor consideration must be given to the amount of voltage to

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be applied across the capacitor. The maximum amount of voltage that can be applied to the capacitor without damage to its dielectric

material is generally given in the data sheets as: WV, (working voltage) or as WV DC, (DC working voltage).If the voltage applied across the capacitor becomes too great, the dielectric will break down (known as electrical breakdown) and arcing will occur between the capacitor plates resulting in a short-circuit. The working voltage of the capacitor depends on the type of dielectric material being used and its thickness.

Surface Area – the surface area, A of the two conductive plates which make up the capacitor, the larger the area the greater the capacitance.

Distance – the distance, d between the two plates, the smaller the distance the greater the capacitance.

Dielectric Material – the type of material which separates the two plates called the “dielectric”,

We have also seen that a capacitor consists of metal plates that do not touch each other but are separated by a material called a dielectric. The dielectric of a capacitor can be air, or even a vacuum but is generally a non-conducting insulating material, such as waxed paper, glass, mica different types of plastics etc. The dielectric provides the following advantages: The dielectric constant is the property of the dielectric

material and varies from one material to another increasing the capacitance by a factor of k.

The dielectric provides mechanical support between the two plates allowing the plates to be closer together without touching.

Permittivity of the dielectric increases the capacitance. The dielectric increases the maximum operating voltage

compared to air.

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4.4 ResistorResistors are electronic components which have a specific, never-changing electrical resistance. The resistor’s resistance limits the flow of electrons through a circuit.They are passive components, meaning they only consume power (and can’t generate it). Resistors are usually added to circuits where they complement active components like op-amps, microcontrollers, and other integrated circuits. Commonly resistors are used to limit current, divide voltages, and pull-up I/O lines.

Resistors can be fabricated in a variety of ways. The most common type in electronic devices and systems is the carbon-composition resistor. Fine granulated carbon (graphite) is mixed with clay and hardened. The resistance depends on the proportion of carbon to clay; the higher this ratio, the lower the resistance.

Dimensions and material affects:The resistance R in ohms (Ω) of a resistor is equal to the resistivity ρ in ohm-meters (Ω∙m) times the resistor's length l in meters (m) divided by the resistor's cross sectional area A in square meters (m2):

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Resistor color code:The resistance of the resistor and its tolerance are marked on the resistor with color code bands that denotes the resistance value.There are 3 types of color codes:4 bands: digit, digit , multiplier, tolerance.5 bands: digit, digit, digit , multiplier, tolerance.6 bands: digit, digit, digit , multiplier, tolerance, temperature coefficient.Pull-up resistor:In digital circuits, pull-up resistor is a regular resistor that is connected to the high voltage supply (e.g +5V or +12V) and sets the input or output level of a device to '1'.The pull-up resistor set the level to '1' when the input / output is disconnected. When the input / output is connected, the level is determined by the device and overrides the pull-up resistor.Pull-down resistor:In digital circuits, pull-down resistor is a regular resistor that is connected to the ground (0V) and sets the input or output level of a device to ' 0 '.The pull-down resistor set the level to ' 0 ' when the input / output is disconnected. When the input / output is connected, the level is determined by the device and overrides the pull-down resistor.

4.5 LM35

The LM35 - An Integrated Circuit Temperature Sensor. The LM35 series are

precision integrated-circuit temperature devices with an output voltage linearly-

proportional to the Centigrade temperature. The LM35 device has an advantage over

linear temperature sensors calibrated in Kelvin, as the user is not required to subtract a

large constant voltage from the output to obtain convenient Centigrade scaling. The

LM35 device does not require any external calibration or trimming to provide typical

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accuracies of ±¼°C at room temperature and ±¾°C over a full −55°C to 150°C

temperature range. Lower cost is assured by trimming and calibration at the wafer

level. The low-output impedance, linear output, and precise inherent calibration of the

LM35 device makes interfacing to readout or control circuitry especially easy. The

device is used with single power supplies, or with plus and minus supplies. As the

LM35 device draws only 60 μA from the supply, it has very low self-heating of less

than 0.1°C in still air. The LM35 device is rated to operate over a −55°C to 150°C

temperature range, while the LM35C device is rated for a −40°C to 110°C range

(−10° with improved accuracy). The LM35-series devices are available packaged in

hermetic TO transistor packages, while the LM35C, LM35CA, and LM35D devices

are available in the plastic TO-92 transistor package. The LM35D device is available

in an 8-lead surface-mount small-outline package and a plastic TO-220 package.

Uses LM35s To Measure Temperature

You can measure temperature more accurately than a using a thermistor.

The sensor circuitry is sealed and not subject to oxidation, etc.

The LM35 generates a higher output voltage than thermocouples and may not

require that the output voltage be amplified.

Working of LM35

It has an output voltage that is proportional to the Celsius temperature.

The scale factor is .01V/oC

The LM35 does not require any external calibration or trimming and maintains

an accuracy of  +/-0.4 oC at room temperature and +/- 0.8 oC over a range of

0 oC to +100 oC.

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Another important characteristic of the LM35DZ is that it draws only 60 micro

amps from its supply and possesses a low self-heating capability. The sensor

self-heating causes less than 0.1 oC temperature rise in still air.

   The LM35 comes in many different packages, including the following.

TO-92 plastic transistor-like package,

T0-46 metal can transistor-like package

8-lead surface mount SO-8 small outline package

TO-202 package. (Shown in the picture above)

In this circuit, parameter values commonly used are:

Vc = 4 to 30v

5v or 12 v are typical values used.

Ra = Vc /10-6

Actually, it can range from 80 K to 600 K , but most just use 80 K.

Here is a photo of the LM 35 wired on a circuit board.

The white wire in the photo goes to the power supply.

Both the resistor and the black wire go to ground.

The output voltage is measured from the middle pin to ground.l

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Features

Calibrated Directly in Celsius (Centigrade)

Linear + 10-mV/°C Scale Factor

0.5°C Ensured Accuracy (at 25°C)

Rated for Full −55°C to 150°C Range

Suitable for Remote Applications

Low-Cost Due to Wafer-Level Trimming

Operates from 4 V to 30 V

Less than 60-μA Current Drain

Low Self-Heating, 0.08°C in Still Air

Non-Linearity Only ±¼°C Typical

Low-Impedance Output, 0.1 Ω for 1-mA Load

4.6 7805 ICVoltage Regulator is one of the most important and commonly used electrical components. Voltage Regulators are responsible for maintaining a steady voltage across an Electronic system. Voltage fluctuations may result in undesirable effect on an electronic system, so to maintaining a steady constant voltage is necessary according to the voltage requirement of a system.The 7805 ic is three terminal positive voltage regulators is available with fixed output voltages making them useful in a wide range of applications. This regulator is inexpensive, vise-to-use devices suitable for a multitude of applications that require a

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regulated supply of up to 800 mA.It includes feature of internal current limiting and thermal shutdown making them remarkably rugged. No external components are required with the 7805 devices in many applications.These devices offer a substantial performance advantage over the traditional zener diode-resistor combination, as output impedance and quiescent current are substantionally reduced.The 7805 is available in 3-Pin plastic package SOT54 (Z),offers superior quality and performance at low cost.A Voltage regulator is a device that automatically maintains a constant voltagelevel. A voltage regulator generates a fixed output voltage of a preset magnitude thatremains constant regardless of changes to its input voltage or load conditions.Electronic voltage regulators are found in devices such as computer power supplieswhere they stabilize the DC voltages used by the processor and other elements.

IC 7805 is a 5V Voltage Regulatorthat restricts the voltage output to 5V and draws 5V regulated power supply. It comes with provision to add heatsink.The maximum value for input to the voltage regulator is 35V. It can provide a constant steady voltage flow of 5V for higher voltage input till the threshold limit of 35V. If the voltage is near to 7.5V then it does not produce any heat and hence no need for heatsink. If the voltage input is more, then excess electricity is liberated as heat from 7805.It regulates a steady output of 5V if the input voltage is in rage of 7.2V to 35V. Hence to avoid power loss try to maintain the input to 7.2V. In some circuitry voltage fluctuation is fatal (for e.g. Microcontroller), for such situation to ensure constant voltage IC

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7805 Voltage Regulator is used. For more information on specifications of 7805 Voltage Regulator please refer the data sheet here (IC 7805 Voltage Regulator Data Sheet). IC 7805 is a series of 78XX voltage regulators. It’s a standard, from the name the last two digits 05 denotes the amount of voltage that it regulates. Hence a 7805 would regulate 5v and 7806 would regulate 6V and so on.

FEATURES High Output Current

IO= 100 mA Fixed Output Voltage

VO= 5 V Available in either ±5% (AC) Selection

The pin explanation of the 7805 is described in the following table:

Pin No

Function NameDESCRIPTION

1 Input voltage (5V-18V) InputIn this pin of the IC positive unregulated voltage is given in regulation.

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2 Ground (0V) Ground

In this pin where the ground is given. This pin is neutral for equally the input and output.

3Regulated output; 5V (4.8V-5.2V)

OutputThe output of the regulated 5V volt is taken out at this pin of the IC regulator.

The schematic given below shows how to use a 7805 IC, there are 3 pins in IC 7805, pin 1 takes the input voltage and pin 3 produces the output voltage. The GND of both input and out are given to pin 2.Pin Description:  

7805 IC working

We have colored the following schematic to indicate the main blocks of the 7805

regulator. The heart of the 7805 chip is a large transistor that controls the current

between the input and output, and thus controls the output voltage. This

transistor (Q16) is red on the diagram below. On the die, it takes up most of the

right half of the chip because it needs to handle over 1 amp of current.

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The main problem with producing a stable voltage from an IC is the chip's

parameters change as temperature changes: it's no good if we have 5 volt phone

charger starts producing 3 or 7 volts on a hot day. The trick to building a stable

voltage reference is to create one voltage that goes down with temperature and

another than goes up with temperature. If you add them together correctly, but

get a voltage that is stable with temperature. This circuit is called a "bandgap

reference".

To create a voltage that goes down with temperature,we have put a constant

current through the transistor and look at the voltage between the base and

emitter, called VBE. The graph below shows how this voltage drops as the

temperature increases. At the left, the line hits the bandgap voltage of silicon,

about 1.2 volts; this will be important later.

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4.7 LCD

LCD-Liquid Crystal Display is an electronic device for displaying text orcharacters.

We are using 14 pin LCD. 16*2 represents 16 characters and 2 line display.

LCD’s are economical and easily programmable and can easily display special

andcustom characters.

Pin description is as follows

1. Pin 7 to pin 14-All 8 pins are responsible for the transfer of data.

2. Pin 4-This is RS i.e., register select pin.

3. Pin 5-This is R/W i.e., Read/Write pin.

4. Pin 6-This is E i.e., enable pin.

5. Pin 2-This is VDD i.e., power supply pin.

6. Pin 1-This is VSS i.e., ground pin.

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7. Pin 3-This is short pin

A 16x2 character LCD with black text on green background display is used. Being

sufficiently wide it serves the purpose of a notice board display screen. It operates at

5V DC with a duty cycle of 1/16. Multiple LCD displays are used among which any

one display can be chosen for displaying the notice.

20 characters wide, 4 rows

White text on blue background

Connection port is 0.1" pitch, single row for easy breadboarding and wiring

Single LED backlight with a resistor included, you can power it directly from

5V. If it's too bright for you, it can be dimmed easily with a resistor or PWM

and uses much less power than LCD with EL (electroluminescent) backlights

Can be fully controlled with only 6 digital lines!

Built in character set supports English/Japanese text, see the HD44780

datasheet for the full character set

Up to 8 extra characters can be created for custom glyphs or 'foreign' language

support (like special accents)

Comes with necessary contrast potentiometer and strip of header

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4.8 Serial Port Bluetooth Module (Master/Slave) : HC-05HC-05 module is an easy to use Bluetooth SPP (Serial Port Protocol) module,

designed for transparent wireless serial connection setup. Serial port Bluetooth

module is fully qualified Bluetooth V2.0+EDR (Enhanced Data Rate) 3Mbps

Modulation with complete 2.4GHz radio transceiver and baseband. It uses CSR

Bluecore 04-External single chip Bluetooth system with CMOS technology and with

AFH(Adaptive Frequency Hopping Feature). It has the footprint as small as

12.7mmx27mm. Hope it will simplify your overall design/development cycle.

The HC-05 is based on the EGBT-045MS Bluetooth module. It can operate as either a

slave device or a master device. As a slave it can only accept connections. As a master

it can initiate a connection.

The EGBT-045MS Bluetooth modules (the smaller daughter board) is a 3.3v device.

The HC-05 break out board has a 3.3v regulator that allows an input voltage of 3.6v to

6v but the TX and RX pins are still 3.3v. This means you can use the 5V out from the

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Arduino to power the boards but you cannot connect the Arduino directly to the HC-

05 RX pin.

For the HC-05 RX pin (data in) we need to convert the Arduinos 5V to 3.3v. A simple

way to do this is by using a voltage divider made from a couple of resistors. In my

case I use a 1K ohm resistor and a 2K ohm resistor.

As a quick guide to the voltage divider; 1K + 2K = 3K. 1K is a third of 3K so it

reduces the voltage by a third.

One third of 5V is 1.66 and 5-1.66 = 3.33 which is what we want. Putting the resistors

the other way would reduce the voltage by 2 thirds. For more information on voltage

dividers have a look at the Sparkfun tutorial

Since the Arduino will accept 3.3 volts as HIGH you can connect the HC-05 TX pin

(data out) directly to the Arduino RX pin (The 5V Arduino takes a voltage of 3V or

more as HIGH).

HC-05 zs-040 Status LEDThe onboard LED shows the current state of the module.

rapid flash (about 5 times a second) module is on and waiting for a connection or

pairing

single quick flash once every 2 seconds the module has just paired with another

device

double quick flash every 2 seconds connected to another device.

The HC-05 remembers devices it has paired with and after cycling the power you do

not need to re-pair. This means you can go from rapid flash (about 5 times a second)

module is on and waiting for a connection or pairing, to double quick flash every 2

seconds connected to another device directly.

ConnectionsHC-05 Vcc to 5V (can be from the +5V out from the Arduino)

HC-05 GND to common GND

HC-05 RX to Arduino pin D3 (TX) via a voltage divider

HC-05 TX to Arduino pin D2 (RX) connect directly

Power on the Arduino and the LED on the HC-05 should flash rapidly, about 5 times

a second. This means it is on but not paired or connected. So far so good.

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Default SettingsThe default settings for new modules are

– Name = HC-05

– Password = 1234

– Baud rate in communication mode = 9600*

–Baud rate in AT/Command mode = 38400

*Not all modules have the same defaults. If you cannot get communication mode

working with 9600 try other baud rates. 38400 is also common.

Thes above values can be changed but for now we will leave the default settings and

try to connect to another device.

Added 12.07.2015

I have some new modules that have a default baud rate of 38400 for both AT mode

and also communication mode. If you cannot get 9600 to work try 38400

Pair with an Android deviceIn my case, the Android device is a 7 inch tablet.

Before you can make a connection between blue tooth devices they need to be paired.

So, with the Arduino and HC-05 powered, on the Android device;

– turn on bluetooth,

– scan for devices and the HC-05 should be listed,

– pair with the HC05 and enter the password “1234” assuming you have the default

password.

Once paired the blinking LED on the HC-05 will change to a single short blink every

2 seconds or so.

Hardware Features

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Typical -80dBm sensitivity

Up to +4dBm RF transmit power

Low Power 1.8V Operation ,1.8 to 3.6V I/O

PIO control

UART interface with programmable baud rate

With integrated antenna

With edge connector

Software Features

Default Baud rate: 38400, Data bits:8, Stop bit:1,Parity:No parity, Data control: has.

Supported baud rate: 9600,19200,38400,57600,115200,230400,460800.

Given a rising pulse in PIO0, device will be disconnected.

Status instruction port PIO1: low-disconnected, high-connected;

PIO10 and PIO11 can be connected to red and blue led separately. When master and slave

are paired, red and blue led blinks 1time/2s in interval, while disconnected only blue led blinks 2times/s.

Auto-connect to the last device on power as default.

Permit pairing device to connect as default.

Auto-pairing PINCODE:”0000” as default

Auto-reconnect in 30 min when disconnected as a result of beyond the range of connection.

AT command Default

How to set the mode to server (master):

1. Connect PIO11 to high level.

2. Power on, module into command state.

3. Using baud rate 38400, sent the “AT+ROLE=1\r\n” to module, with “OK\r\n” means setting successes.

4. Connect the PIO11 to low level, repower the module, the module work as server (master).

AT commands: (all end with \r\n)

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Chapter 5

CONCLUSION

The display boards are one of the major communications medium for mass media.

Local language can be added as a variation in this project. This can be achieved by

using graphics and other decoding techniques. Also we realize that this project saves

time, energy and hence environment. Cost of printing and photocopying is also

reduced as information can be given to a large number of people from our fingertips.

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REFRENCEShttp://www.engineersgarage.com/articles/bluetooth-technology

http://www.instructables.com/id/Interfacing-20x4-LCD-with-Arduino/?ALLSTEPS.

https://www.adafruit.com/product/198

http://www.engineersgarage.com/contribution/expert/wireless-notice-board-project

http://ethesis.nitrkl.ac.in/51/1/10307006.pdf

http://www.instructables.com/id/Arduino-AND-Bluetooth-HC-05-Connecting-

easily/?ALLSTEPS

https://en.wikipedia.org/wiki/Resistor

https://en.wikipedia.org/wiki/Capacitor

https://learn.sparkfun.com/tutorials/what-is-an-arduino

https://www.sparkfun.com/datasheets/Components/LM7805.pdf

http://www.facstaff.bucknell.edu/mastascu/elessonshtml/sensors/templm35.html

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