Push Button Switch[2]

PASSWORD BASED SECURITY DOOR LOCK SYSTEM

A PROJECT REPORT

Submitted by

ARPAN SINHA 0102092808

CHHAVI GOYAL 0412092808

DEEKSHA AGGARWAL 0562092808

SNEHA 0602092808

in partial fulfillment for the award of the degree

Of

BACHELORS OF TECHNOLOGY

In

ELECTRONICS AND COMMUNICATION ENGINEERING

AT

DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERINGGB PANT ENGINEERING COLLEGE

OKHLA INDUSTRIAL ESTATENEW DELHI 110019

DECEMBER 2011

i

LIST OF TABLES

CHAP-TER NO.

TABLE NO

TABLE TITLE PAGE NO

3. 3.1.1 Alternate functions of Port 1 11

3.1.2 Alternate functions of Port 3 11

3.4.1 Pin Description of AT24C02 16

3.5.1 Pin description of 16x2 18

3.5.2 LCD command codes 20

ii

LIST OF FIGURES

CHAP-TER NO.

FIG NO.

FIGURE TITLE PAGE

NO.2. 2.1 Circuit diagram of PASSWORD BASED SE-

CURITY DOOR LOCK SYSTEM

6

3 3.1.1 Microcontroller AT89S52 9

3.1.2 Pin Configuration of AT89S52 10

3.2.1 Symbol of an LED 13

3.2.2

3.2.3

3.3.1

3.3.2

3.4.1

3.5.1

3.5.2

3.6.1

3.6.2

3.7.1

3.7.2

3.8.1(a

)

3.8.1(b

)

3.9.1

3.10.1

Parts of an LED

Recombination in an LED

Variants of Push Button Tact Switch

Working of Push Button Tact Switch

Pin Diagram of AT24C02

16X2 LCD

Pin diagram of 16x2 LCD

Types of resistors

Colour coding of resistor

Ceramic Capacitor

Electrolytic Capacitor

Step Down Transformer

9-0-9 Step Down Transformer

7805 IC

Full Wave Rectification

IN4007 diode

Equivalent circuit of crystal oscillator

13

14

15

15

16

17

18

22

23

24

24

26

26

27

28

30

32

iii

3.11.1

3.12.1

4. 4.1 Interfacing of Microcontroller 34

4.1.1 16X2 LCD Display 34

4.1.2 Interfacing of AT89S52 with 16X2 LCD Dis-

play

35

4.2.1 Interfacing with Push button switches 36

4.3.1 Interfacing Microcontroller with reset switch 37

4.4.1 Interfacing of crystal oscillator with Microcon-troller

37

4.5.1 Interfacing of output LED with Microcontroller 38

iv

DECLARATION

We hereby declare that the project work entitled “PASSWORD BASED SECU-

RITY DOOR LOCK SYSTEM” submitted to the G.B.Pant Engineering Col-

lege, Delhi is a record of an original work done by us under the guidance of

Mrs. Monika Garg, and this project work is submitted in the partial fulfillment

of the requirements for the award of the degree of Bachelor of Technology in

Electronics & Communication Engineering. The results embodied in this thesis

have not been submitted to any other University or Institute for the award of any

degree or diploma.

Arpan Sinha Chhavi Goyal Deeksha Aggarwal Sneha(0102092808) (0412092808) (0562092808) (0602092808)

Date:Place:

v

G.B. PANT ENGINEERING COLLEGEDELHI

GGSIP UNIVERSITY: NEW DELHI

BONAFIDE CERTIFICATE

THIS IS CERTIFIED THAT THIS PROJECT REPORT “PASSWORD

BASED SECURITY DOOR LOCK SYSTEM” IS THE BONAFIDED

WORK OF “ARPAN SINHA, CHHAVI GOYAL, DEEKSHA

AGGARWAL & SNEHA” WHO CARRIED OUT THE PROJECT

WORK UNDER MY SUPERVISION.

SIGNATURE SIGNATUREMAMTA JAIN MONIKA GARGHEAD OF THE DEPARTMENT SUPERVISOR

ECE (ASSISTANT PROFESSOR) ECE

vi

vii

ACKNOWLEDGEMENT

We place on record and warmly acknowledge the continuous encouragement,

invaluable supervision, timely suggestions and inspired guidance offered by our

Lecturer, Department of Electronics and Communication Engineering, G.B.Pant

Engineering College, Delhi in bringing this project to a successful completion.

We are grateful to Mrs. Mamta Jain, Head of Department of Electronics and

Communication Engineering and Mrs. Monika Garg, Assistant Professor

(E.C.E) for permitting us to make use of the facilities available in the depart-

ment to carry out the project successfully. Last but not least we express our sin-

cere thanks to all of our friends who have patiently extended all sort of help for

accomplishing this undertaking.

Finally we extend our gratefulness to one and all who are directly and indirectly

involved in the successful completion of this project work.

ARPAN SINHACHHAVI GOYALDEEKSHA AGGARWALSNEHA

8

ABSTRACT

Home/office security is a prime concern for everyone. Access control is the

ability to permit or deny the use of a system by a particular entity. The main

idea of designing digital locking system is to provide more secure security sys-

tem than mechanical lock; here key pad is used to enter the password. If that

password matches with the password already stored in flash of the controller

then the LED blows which can be replaced by a DC motor in future for practical

application for opening the door and if the password is entered wrong more than

three times then the buzzer is activated.

System can work in two modes- User Mode and Master Mode. User mode pass-

word is changeable and the user can login through the user mode only. Master

mode password is fixed and cannot be changed. It is used to change the user

mode password. Master code is not known to everyone, it is kept only for secu-

rity purpose. Whenever a user would like to access the system, he is asked for a

password which is provided to him and if the password entered by him is cor-

rect he is allowed to access the system otherwise the door will not be opened

and INCORRECT will be displayed on the LCD display, which means either he

is not authorized to access the system or he may forget the password.

9

TABLE OF CONTENTS

CHAPTER NO.

TITLE PAGE NO.

LIST OF TABLES ii

LIST OF FIGURES iii

DECLARATION v

CERTIFICATE vi

ACKNOWLEDGEMENT vii

ABSTRACT viii

1. INTRODUCTION

1.1 CHARACTERISTICS OF AN EMBEDDED SYSTEM

1.2 COMPONENTS REQUIRED

1

2

3

2. DESIGN AND DEVELOPMENT OF PASSWORD

BASED SECURITY DOOR LOCK SYSTEM

2.1 WORK APPROACH.

4

5

3. DESCRIPTION OF COMPONENTS

3.1 MICROCONTROLLER AT89S52

3.1.1 FEATURES

3.1.2 DESCRIPTION

3.1.3 PIN CONFIGURATION

3.1.4 PIN DESCRIPTION

8

10

3.2 LIGHT EMITTING DIODE (LED)

3.2.1 WORKING 3.2.2 ADVANTAGES OF LED 3.2.3 DISADVANTAGES OF LED

3.3 PUSH BUTTON TACT SWITCH

3.3.1 WORKING

3.4 EEPROM 24C02 | AT24C02

3.4.1 PIN DIAGRAM

3.4.2 PIN DESCRIPTION

3.5 16x2 LIQUID CRYSTAL DISPLAY

3.5.1 PIN DIAGRAM

3.5.2 PIN DESCRIPTION

3.5.3 LCD COMMAND CODES

3.6 RESISTORS

3.6.1 TYPES OF RESISTORS

3.6.2 COLOUR CODING OF RESISTOR

3.7 CAPACITORS

3.7.1 TYPES OF CAPACITORS

3.8 TRANSFORMER

3.9 VOLTAGE REGULATOR

3.9.1 7805 VOLTAGE REGULATOR IC

11

3.9.2 ADVANTAGES OF 7805 IC

3.10 CENTER TAP FULL WAVE RECTIFIER

3.11 IN4007 DIODE

3.12 CRYSTAL OSCILLATOR

3.12.1 OPERATION

4 INTERFACING WITH MICROCONTROLLER

4.1 INTERFACING OF LCD.

4.2 INTERFACING OF SWITCHES

4.3 INTERFACING OF RESET SWITCH

4.4 INTERFACING OF CRYSTAL OSCILLATOR

4.5. INTERFACING OF OUTPUT LED

15

5 PROGRAMMING THE MICRO CONTROLLER 61

5.1 KEIL SOFTWARE 65

5.2 PROGRAMMING AT89S52 IN DIGITAL LOCK SYSTEM

65

6. BIBLIOGRAPHY 89

12

CHAPTER 1INTRODUCTION

13

An embedded system is a computer system designed for specific control func-

tions within a larger system often with real-time computing constraints. It is a

combination of software and hardware to perform a dedicated task. Basically an

embedded system is a computer, designed for specific control functions within a

large system like traffic lights, factory controllers, MP3 players etc. Embedded

systems contain processing cores that are typically either microcontrollers or

digital signal processors (DSP). The key characteristic, however, is being dedi-

cated to handle a particular task.

1.1 CHARACTERISTICS OF AN EMBEDDED SYSTEM

1. Embedded systems are designed to do some specific task, rather than be a

general-purpose computer for multiple tasks. Some also have real-time perfor-

mance constraints that must be met, for reasons such as safety and usability;

others may have low or no performance requirements, allowing the system

hardware to be simplified to reduce costs.

2. Embedded systems are not always standalone devices. Many embedded sys-

tems consist of small, computerized parts within a larger device that serves a

more general purpose. For example, an embedded system in an automobile pro-

vides a specific function as a subsystem of the car itself.

3. The program instructions written for embedded systems are referred to as

firmware, and are stored in read-only memory or Flash memory chips. They run

with limited computer hardware resources: little memory, small or non-existent

keyboard and/or screen. In this project, an embedded system is designed to pro-

vide security to homes, offices by developing a digital door lock system. Some

of the components used in this project given below which are described in detail

in chapter 3.

14

1.2 COMPONENTS REQUIRED

Microcontroller AT89S52

LCD 16X2

LED

Capacitors

Resistors

Push button tact switches

Transformer

Crystal oscillator

EEPROM

Voltage regulator

Diode

PCB

Soldering Iron

Connecting Wires

15

CHAPTER 2DESIGN AND DEVELOP-

MENT OF PASSWORD BASED SECURITY DOOR

LOCK SYSTEM

16

2.1 Work Approach

Aim of this project is to develop a digital lock in which the security is

provided by means of passwords. If the password is correct then the door

will open otherwise it remains close.

To implement this project the main component is microcontroller. Here

we are using Microcontroller AT89s52 because of its specific features

like 8 kilo bytes of in system programmable memory, three level program

memory lock, 256 bytes of internal RAM, low cost etc.

To enter the password push button tact switches are used. Nine switches

are used for numeric digits from 0-9 and two for E and M buttons. M

stands for Mode. It is use to switch between user mode and master mode.

Whereas, E stands for Enter button.

To display the result and the password a 16X2 LCD is used. It displays

the password in the form of asterisk (*). It also displays the result whether

the password entered is correct or not.

These components need sufficient amount of power supply to work effi-

ciently. Microcontroller AT89S52 and LCD need a power supply of

5v.Here the power supply section is consists of step down transformer

which convert 220 v to 9v,rectifier to convert AC supply to DC, regulator

to further step down the voltage to 5v and capacitor for smoothing of the

output voltage

If the password entered is correct LED glows for predefined amount of

time already stored in the Microcontroller.

The circuit diagram showing the interfacing between these components is

shown in figure 2.1

17

Fig 2.1: Circuit diagram of PASSWORD BASED

SECURITY DOOR LOCK SYSTEM

18

CHAPTER 3IMPLEMENTATION AND

SELECTION OFCOMPONENTS

19

3.1 MICROCONTROLLER AT89S52

Microprocessors and microcontrollers are widely used in embedded systems

products. Microcontroller is a programmable device. A microcontroller has a

CPU in addition to a fixed amount of RAM, ROM, I/O ports and a timer em-

bedded all on a single chip. The fixed amount of on-chip ROM, RAM and num-

ber of I/O ports in microcontrollers makes them ideal for many applications in

which cost and space are critical.

Microcontroller part can be found in all electronics devices. Microcontroller can

be found in devices which are used in home like microwave oven, automatic

brake systems, etc. Microcontroller helps in doing job easily and safely.

3.1.1 FEATURES

• Compatible with MCS®-51 Products

• 8K Bytes of In-System Programmable (ISP) Flash Memory

• 4.0V to 5.5V Operating Range

• Fully Static Operation: 0 Hz to 33 MHz

• Three-level Program Memory Lock

• 256 x 8-bit Internal RAM

• 32 Programmable I/O Lines

• Three 16-bit Timer/Counters

• Eight Interrupt Sources

• Full Duplex UART Serial Channel

• Low-power Idle and Power-down Modes

• Watchdog Timer

• Dual Data Pointer

• Fast Programming Time

• Flexible ISP Programming (Byte and Page Mode)

20

3.1.2 DESCRIPTION

The Microcontroller AT89S52 (shown in Fig 3.1.1) is a low-power, high-

performance CMOS 8-bit microcontroller with 8K bytes of in-system

programmable Flash memory. The device is manufactured using Atmel’s high-

density non-volatile memory technology and is compatible with the industry-

standard 80C51 instruction set and pin out. The on-chip Flash allows the

program memory to be reprogrammed in-system or by a conventional non-

volatile memory programmer. By combining a versatile 8-bit CPU with in-

system programmable Flash on a monolithic chip, the Atmel AT89S52 is a

powerful microcontroller which provides a highly-flexible and cost-effective

solution to many embedded control applications.

The AT89S52 is designed with static logic for operation down to zero frequency

and supports two software selectable power saving modes. The Idle Mode stops

the CPU while allowing the RAM, timer/counters, serial port, and interrupt sys-

tem to continue functioning. The Power-down mode saves the RAM con-tents

but freezes the oscillator, disabling all other chip functions until the next inter-

rupt or hardware reset.

Fig 3.1.1: MICROCONTROLLER AT89S52

21

3.1.3 PIN CONFIGURATION

Fig 3.1.2: Pin Configuration of AT89S52

3.1.4 PIN DESCRIPTION

VCC: Supply voltage

GND: Ground

Port 0: Port 0 is an 8-bit open drain bidirectional I/O port. As an output port,

each pin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins

can be used as high-impedance inputs. External pull-ups are required during

program verification.

Port 1: Port 1 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 1

output buffers can sink/source four TTL inputs. When 1s are written to Port 1

pins, they are pulled high by the internal pull-ups and can be used as inputs.

Port 1 also receives the low-order address bytes during Flash programming and

verification.

Table shows the alternate functions performed by port 1 as timer/counter

22

Table 3.1.1: Alternate functions of Port 1

Port 2: Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 2

output buffers can sink/source four TTL inputs. When 1s are written to Port 2

pins, they are pulled high by the internal pull-ups and can be used as inputs.

Port 2 also receives the high-order address bits and some control signals during

Flash programming and verification.

Port 3: Port 3 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 3

output buffers can sink/source four TTL inputs. When 1s are written to Port 3

pins, they are pulled high by the internal pull-ups and can be used as inputs.

Port 3 also serves the functions of various special features of the AT89S52, as

shown in the following table.

Table 3.1.2: Alternate functions of Port 3

RST: Reset input. A high on this pin for two machine cycles while the oscilla-

tor is running resets the device. This pin drives high for 98 oscillator periods af-

ter the Watchdog times out.

23

ALE/PROG: Address Latch Enable (ALE) is an output pulse for latching the

low byte of the address during accesses to external memory. This pin is also the

program pulse input (PROG) during Flash programming.

PSEN: Program Store Enable (PSEN) is the read strobe to external program

memory. When the AT89S52 is executing code from external program memory,

PSEN is activated twice each machine cycle, except that two PSEN activations

are skipped during each access to external data memory.

EA/VPP: External Access Enable. EA must be strapped to GND in order to en-

able the device to fetch code from external program memory locations starting

at 0000H up to FFFFH. Note, however, that if lock bit 1 is programmed, EA

will be internally latched on reset.

EA should be strapped to VCC for internal program executions. This pin also

receives the 12-volt programming enable voltage (VPP) during Flash program-

ming.

XTAL1: Input to the inverting oscillator amplifier and input to the internal

clock operating circuit.

XTAL2: Output from the inverting oscillator amplifier.

3.2 LIGHT EMITTING DIODE (LED)

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.

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 Fig 3.2.1 shows symbol of an LED. This effect is called electrolu-

minescence and the color of the light (corresponding to the energy of the pho-

ton) is determined by the energy gap of the semiconductor. LEDs are 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

24

light sources including lower energy consumption, longer lifetime, improved ro-

bustness, smaller size, and faster switching. LEDs powerful enough for room

lighting are relatively expensive and require more precise current and heat man-

agement than compact fluorescent lamp sources of comparable output. Fig 3.2.2

shows different parts of an LED. .

Fig 3.2.1: Symbol of an LED

Fig 3.2.2: Parts of an LED

3.2.1 WORKING

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

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

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

electrons and holes flow into the junction from electrodes with different

voltages. When an electron meets a hole, it falls into a lower energy level, and

releases energy in the form of a photon as shown in fig 3.2.3.

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

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

25

diodes, the electrons and holes recombine by a non-radioactive transition, which

produces no optical emission, because these are indirect band gap materials.

Fig 3.2.3: Recombination in an LED

3.2.2 ADVANTAGES OF LED:

Efficiency: LEDs produce more light per watt than incandescent

bulbs; this is useful in battery powered or energy-saving devices.

Colour: LEDs can emit light of an intended colour without the use of

colour filters that traditional lighting methods require. This is more ef-

ficient and can lower initial costs.

Size: LEDs can be very small (>2 mm2) and are easily populated onto

printed circuit boards.

3.2.3 DISADVANTAGES OF LED:

Temperature Dependence: LED’s performance largely depends on the

ambient temperature of the operating environment.

LED’s must be supplied with the correct current.

3.3 PUSH BUTTON TACT SWITCH

A pushbutton tact switch is a simple switch mechanism which permits user

generated changes in the state of a circuit. It is a type of switch that is only ON

26

when the button is pressed as shown in Fig 3.3.1. As soon the button is released,

the circuit breaks. It can be thought as keys on a keyboard.

Fig 3.3.1: Variants of Push Button Tact Switch

3.3.1 WORKING

As shown in fig 3.3.2, the switch has four pins which are linked in pairs by in-

ternal metal strips. Pressing the button bridges the contacts and closes the

switch. The extra pins are useful in designing printed circuit boards for key-

board input and also stop the switch from being moved about or bent once sol-

dered into position.

Fig 3.3.2: Working of Push Button Tact Switch

3.4 EEPROM 24C02 | AT24C02

AT24C02 is an electrically erasable and programmable ROM. It has a 2Kbits of

memory size arranged in 32 pages of 8 byte each. There are 256 (32 x 8) words

each of one byte.

27

3.4.1 PIN DIAGRAM

Fig 3.4.1 shows the Pin Diagram of AT24C02. The data is transferred and re-

ceived serially through serial data (SDA) pin. The SCL is clock input and is

used to synchronize EEPROM with microcontroller for various operations.

When data is to be read or write, first a start condition is created followed by

device address, byte address and the data itself. Finally a stop condition is pro-

vided. The start condition occurs when SDA and SCL get high to low simulta-

neously. The stop condition is when SDA remains low while SCL goes from

high to low. The data is read or written between the start and stop conditions on

every transition of SCL from high to low.

Fig 3.4.1: Pin Diagram of AT24C02

3.4.2 PIN DESCRIPTION

TABLE 3.4.1: Pin Description of AT24C02

 Pin No Function Name

1 Address input pins; Provide addresses when

more than one EEPROM is interfaced to a

single microcontroller;

Ground when only one EEPROM is used

 AD0

2  AD1

3  AD2

4 Ground (0V) Ground

28

5 Bi-directional pin for serial data transfer Serial Data

6 Provides clock signals Serial Clock

7 Ground allows normal read/write functions;

Vcc enables write protection

Write protect

8 Supply voltage; 5V (up to 5.5V) Vcc

3.5 16x2 LIQUID CRYSTAL DISPLAY

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

(LCs). LCs does not emit light directly. LCs are used in a wide range of

applications, including computer monitors, television, instrument panels,

aircraft cockpit displays, signage, etc. They are common in consumer devices

such as video players, gaming devices, clocks, watches, calculators, and

telephones. LCDs have replaced cathode ray tube (CRT) displays in most

applications. They are available in a wider range of screen sizes than CRT and

plasma displays, and since they do not use phosphors, they cannot suffer image

burn-in.

Fig 3.5.1 shows a 16 Character x 2 Line LCD. Each pixel of an LCD typically

consists of a layer of molecules aligned between two transparent electrodes, and

two polarizing filters, the axes of transmission of which are (in most of the

cases) perpendicular to each other. With no actual liquid crystal between the

polarizing filters, light passing through the first filter would be blocked by the

second (crossed) polarizer.

Fig 3.5.1: 16X2 LCD

29

3.5.1 PIN DIAGRAM

Fig 3.5.2: Pin diagram of 16x2 LCD

3.5.2 PIN DESCRIPTION

PIN SYMBOL I/O DESCRIPTION

1 VSS -- Ground

2 VCC -- +5V power supply

3 VEE -- Power supply to control contrast

4 RS I RS=0 to select command register

RS=1 to select data register

5 R/W I R/W=0 for write

R/W=1 for read

6 EN I/O Enable

7 DB0 I/O The 8-bit data bus

8 DB1 I/O The 8-bit data bus

9 DB2 I/O The 8-bit data bus

10 DB3 I/O The 8-bit data bus

11 DB4 I/O The 8-bit data bus

12 DB5 I/O The 8-bit data bus

13 DB6 I/O The 8-bit data bus

30

14 DB7 I/O The 8-bit data bus

Table 3.5.1: Pin description of 16x2

VCC, VSS and VEE:

While VCC and VSS provide with +5V and ground respectively, VEE is used

for controlling LCD contrast.

RS (REGISTER SELECT):

There are two important registers inside the LCD. When RS is low (0), the data

is to be treated as a command or special instruction (such as clear screen,

position). When RS is high (1), the data that is sent is a text data which should

be displayed on the screen. For example, to display the letter "T" on the screen

RS should be set high.

RW (READ/WRITE):

The RW line is the "Read/Write" control line. When RW is low (0), the

information on the data bus is being written to the LCD. When RW is high (1),

the program is effectively querying (or reading) the LCD. Only one instruction

("Get LCD status") is a read command. All others are write commands, so RW

will almost be low.

EN (ENABLE):

The EN line is called "Enable". This control line is used to tell the LCD that

data is being sent. To send data to the LCD, first set this line high (1) and then

set the other two control lines and/or put data on the data bus.

D0-D7 (DATA LINES):

The 8-bit data pins, D0-D7 are used to send information to the LCD or read the

content of the LCD’s internal registers. To display letters and numbers, ASCII

codes for the letters A-Z, a-z and numbers 0-9 are sent to these pins while

making RS=1. There are also instruction command codes that can be sent to the

LCD to clear the display or force the cursor to the home position or blink the

cursor.

31

3.5.3 LCD COMMAND CODES:

CODE (HEX) COMMAND TO LCD INSTRUCTION REGISTER

1 CLEAR DISPLAY SCREEN

2 RETURN HOME

4 DECREMENT CURSOR(SHIFT CURSOR TO LEFT)

6 INCREMENT CURSOR(SHIFT CURSOR TO RIGHT)

5 SHIFT DISPLAY RIGHT

7 SHIFT DISPLAY LEFT

8 DISPLAY OFF,CURSOR OFF

A DISPLAY OFF,CURSOR ON

C DISPLAY ON,CURSOR OFF

E DISPLAY ON CURSOR BLINKING

F DISPLAY ON CURSOR BLINKING

10 SHIFT CURSOR POSITION TO LEFT

14 SHIFT CURSOR POSITION TO RIGHT

18 SHIFT THE ENTIRE DISPLAY TO THE LEFT

1C SHIFT THE ENTIRE DISPLAY TO THE RIGHT

80 FORCE CURSOR TO BEGINNING OF 1ST LINE

C0 FORCE CURSOR TO BEGINNING OF 2ND LINE

38 2 LINES AND 5x7 MATRIX

Table 3.5.2: LCD command codes

3.6 RESISTORS

A linear resistor is a linear, passive two terminal electrical component that im-

plements electrical resistance as a circuit element. The current through a resistor

is in direct proportion to the voltage across the resistor's terminals. Resistors are

common elements of electrical networks and electronic circuits and are ubiqui-

tous in most electronic equipment. The electrical functionality of a resistor is

32

specified by its resistance: common commercial resistors are manufactured over

a range of more than nine orders of magnitude. When specifying that resistance

in an electronic design, the required precision of the resistance may require at-

tention to the manufacturing tolerance of the chosen resistor, according to its

specific application. The temperature coefficient of the resistance may also be

of concern in some precision applications.

3.6.1 TYPES OF RESISTORS

There are various types of resistors available in the market according to the re-

quirement. From operating conditions point of view, resistors can be classified

into two. Fig 3.6.1 shows some of these resistors.

1) Fixed resistors

2) Adjustable/ variable resistors

1) Fixed resistors are further classified into:

a) Carbon composition type resistors b) Metalized type resistors c) Wire wound

type resistors

a) Carbon composition type resistors:

This is the most common type of low wattage resistor. The resistive material is

of carbon-clay composition and the leads are made of tinned copper. These re-

sistors are cheap and reliable and stability is high.

b) Wire wound resistors:

These resistors are a length of wire wound an insulating cylindrical core. Usu-

ally wires of material such as constantan (60% copper and 40% nickel) and

manganin which have high resistivity and low temperature coefficients are em-

33

ployed. The completed wire wound resistor is coated with an insulating material

such as baked enamel.

c) Metalized resistors

It is constructed using film deposition techniques of depositing a thick film of

resistive material onto an insulating substrate. Only approximate value of resis-

tance can be had by this method.

2) Variable resistors

For circuits requiring a resistance that can be adjusted while it remains con-

nected in the circuit (for e.g.: volume control on radio), variable resistors are re-

quired. They usually have 3 lead two fixed and one movable. Variable resistors

are often called potentiometers, or for short, because one very common use for

them is adjustable voltage divider.

Fig 3.6.1: Types of resistors

34

3.6.2 COLOUR CODING OF RESISTOR

Fig 3.6.2: Colour coding of resistor

3.7 CAPACITORS

A capacitor (formerly known as condenser) is a passive two-terminal electrical

component used to store energy in an electric field. The forms of practical ca-

pacitors vary widely, but all contain at least two electrical conductors separated

by a dielectric (insulator). When there is a potential difference (voltage) across

the conductors, a static electric field develops across the dielectric, causing pos-

itive charge to collect on one plate and negative charge on the other plate. En-

ergy is stored in the electrostatic field. An ideal capacitor is characterized by a

single constant value, capacitance, measured in farads.

Capacitors are widely used in electronic circuits for blocking direct current

while allowing alternating current to pass, in filter networks, for smoothing the

output of power supplies, in the resonant circuits that tune radios to particular

frequencies and for many other purposes.

3.7.1 TYPES OF CAPACITORS

35

Although all capacitors work in essentially the same way, key difference in the

construction of different capacitor types makes an enormous difference in their

properties.

The main element of the capacitor that gives rise to the different properties of

the different types of capacitor is the dielectric - the material between the two

plates. Its dielectric constant will alter the level of capacitance that can be

achieved within a certain volume.

Some of the major types are outlined below:

Ceramic capacitor:   The ceramic capacitor is a type of capacitor that is used

in many applications from audio to RF. Values range from a few picofarads to

around 0.1 microfarads. Ceramic capacitor is shown in the adjacent figure.

Fig 3.7.1: Ceramic Capacitor

Electrolytic capacitor:   Electrolytic capacitors are a type of capacitor that is

polarised. They are able to offer high capacitance values typically above 1μF,

and are most widely used for low frequency applications are power supplies, de-

coupling and audio coupling applications as they have a frequency limit if

around 100 kHz.

Fig 3.7.2: Electrolytic Capacitor

36

3.8 TRANSFORMER

A transformer is a device that transfers electrical energy from one circuit to an-

other through inductively coupled conductors—the transformer's coils. A vary-

ing current in the first or primary winding creates a varying magnetic flux in the

transformer's core and thus a varying magnetic field through the secondary

winding. This varying magnetic field induces a varying electromotive force

(EMF), or "voltage", in the secondary winding. This effect is called inductive

coupling.

If a load is connected to the secondary, current will flow in the secondary wind-

ing and electrical energy will be transferred from the primary circuit through the

transformer to the load. In an ideal transformer, the induced voltage in the sec-

ondary winding (Vs) is in proportion to the primary voltage (Vp), and is given by

the ratio of the number of turns in the secondary (Ns) to the number of turns in

the primary (Np) as follows:

By appropriate selection of the ratio of turns, a transformer thus enables an al-

ternating current (AC) voltage to be "stepped up" by making Ns greater than Np,

or "stepped down" by making Ns less than Np. Fig 3.8.1 shows a step down

transformer 9-0-9 which is used to step down from 220V to 9V.It’s current rat-

ing is 750 ma.

37

Fig 3.8.1(a): Step Down Transformer (b):9-0-9 Step Down Transformer

3.9 VOLTAGE REGULATOR

A voltage regulator is an electrical regulator designed to automatically maintain

a constant voltage level. A voltage regulator may be a simple "feed-forward"

design or may include negative feedback control loops. It may use an electro-

mechanical 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

3.9.1 7805 VOLTAGE REGULATOR IC

The 7805 voltage regulator employs built-in current limiting, thermal

shutdown, and safe-operating area protection which make it virtually immune to

damage from output overloads. 7805 is a three-terminal positive voltage

regulator as shown in fig 3.9.1.With adequate heat sinking, it can deliver in

excess of 0.5A output current. Typical applications would include local (on-

card) regulators which can eliminate the noise and degraded performance

associated with single-point regulation.

38

Fig 3.9.1: 7805 IC

3.9.2 ADVANTAGES OF 7805 IC

The 7805 series has several key advantages over many other voltage regulator

circuits which have resulted in its popularity:

7805 series ICs do not require any additional components to provide a

constant, regulated source of power, making them easy to use, as well as

economical, and also efficient uses of circuit board real estate. By con-

trast, most other voltage regulators require several additional components

to set the output voltage level, or to assist in the regulation process. Some

other designs (such as a switching power supply) can require not only a

large number of components but also substantial engineering expertise to

implement correctly as well.

7805 series ICs have built-in protection against a circuit drawing too

much power. They also have protection against overheating and short-

circuits, making them quite robust in most applications. In some cases,

the current-limiting features of the 7805 devices can provide protection

not only for the 7805 itself, but also for other parts of the circuit it is used

in, preventing other component from being damaged as well.

39

3.10 CENTER TAP FULL WAVE RECTIFIER

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.

A full-wave rectifier (as shown in fig 3.10.1) 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 is more efficient.

For single-phase AC, if the transformer is center-tapped, then two diodes back-

to-back (i.e. anodes-to-anode or cathode-to-cathode) can form a full-wave recti-

fier. Twice as many windings are required on the transformer secondary to ob-

tain the same output voltage compared to the bridge rectifier above. This recti-

fier circuit is called full-wave because it makes use of the entire waveform, both

positive and negative half-cycles, of the AC source voltage in powering the DC

load. As a result, there is less "ripple" voltage seen at the load. The RMS (Root-

Mean-Square) value of the rectifier's output is also greater for this circuit than

for the half-wave rectifier.

Fig 3.10.1: Full Wave Rectification

3.11 IN4007 DIODE

Generally IN4007 diode is used in full wave rectifier because of following spec-

ification given below:

40

1)Low forward voltage drop

2)High surge current capacity

3)High stability

4)Comply with RoHS

5)High quality and competitive price

These diodes are used to convert AC into DC. These are used as half wave recti-

fier or full wave rectifier. Three points must he kept in mind while using any

type of diode.

1.) Maximum forward current capacity

2.) Maximum reverse voltage capacity

3.) Maximum forward voltage capacity awesome

The number and voltage capacity of some of the important diodes available in

the market are as follows:

Diodes of number IN4001, IN4002, IN4003, IN4004, IN4005, IN4006 and

IN4007 have maximum reverse bias voltage capacity of 50V and maximum for-

ward current capacity of 1 Amp.

Diode of same capacities can be used in place of one another. Besides this,

diode of more capacity can be used in place of diode of low capacity but diode

of low capacity cannot be used in place of diode of high capacity. For example,

in place of IN4002; IN4001 or IN4007 can be used but IN4001 or IN4002 can-

not be used in place of IN4007.The diode BY125made by company BEL is

equivalent of diode from IN4001 to IN4003. BY 126 is equivalent to diodes

IN4004 to 4006 and BY 127 is equivalent to diode IN4007. IN4007 diode is

shown in the adjacent figure.

41

Fig 3.11.1: IN4007 DIODE

One disadvantage of this full-wave rectifier design is the necessity of a trans-

former with a center-tapped secondary winding. If the circuit in question is one

of high power, the size and expense of a suitable transformer is significant.

Consequently, the center-tap rectifier design is seen only in low-power applica-

tions.

3.12 CRYSTAL 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 very precise frequency. This 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 became known as "crystal

oscillators."

3.12.1 OPERATION

A 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 di-

mensions.

Almost any object made of an elastic material could be used like a crystal, with

appropriate transducers, since all objects have natural resonant frequencies of

42

vibration. For example, steel is very elastic and has a high speed of sound. It

was often used in mechanical filters before quartz. The resonant frequency de-

pends 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 piezoelectricity. When the field is removed, the

quartz will generate 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 a circuit

composed of an inductor, capacitor and resistor, with a precise resonant fre-

quency.

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 will depend on the mode of vibration and the angle at

which the quartz is cut (relative to its crystallographic axes).Therefore, the reso-

nant frequency of the plate, which depends on its size, will not change much, ei-

ther. This means that a quartz clock, filter or oscillator will remain 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.

The equivalent circuit for the quartz crystal shows an RLC series circuit, which

represents the mechanical vibrations of the crystal, in parallel with a capaci-

tance, Cp which represents the electrical connections to the crystal. Quartz crys-

tal oscillators operate at "parallel resonance", and the equivalent impedance of

43

the crystal has a series resonance where Cs resonates with inductance, L and a

parallel resonance where L resonates with the series combination of Cs and Cp

as shown below in Fig 3.12.1.

Fig 3.12.1: Equivalent circuit of crystal oscillator

44

CHAPTER-4INTERFACING

WITHMICROCONTROLLER

45

Interfacing basically means connection of different component to form a com-plete system. In this project following components are interfaced with micro controller:

16X2 LCD

Push button switches

Reset switch of microcontroller

Crystal oscillator

An overall interfacing of microcontroller with different component is shown be-

low

Fig 4.1: Interfacing of Microcontroller

4.1 INTERFACING WITH LCD.

As described above 2X16 LCD display has been used, with 16 pins and each

pin having a particular function. Fig. 4.1.1 shows the 16X2 LCD display with

16 pins.

Fig 4.1.1: 16X2 LCD display

46

OUTPUT

16X2 LCD,LED

MICROCONTROLLER

AT89S52

INPUT12 PUSH BUTTON TACT SWITCHES

POWER SUPPLY 5V

LCD 16X2

For interfacing 16X2 LCD display with microcontroller, port 0 and port 2

of the microcontroller is used.

Pin 0.0 to pin 0.7 is connected to data lines i.e. pin 7 to pin 14 of the LCD

display with pull up registers.

P2.7 is connected to the enable pin of the circuit.

P2.5 is connected to the RS pin of the LCD.

P2.6 is connected to the R/w pin of the LCD.

LCD interfacing with AT89s52 microcontroller is shown in Fig 4.1.2.

Last two pins of the LCD are connected to the back light. Some time

these are internally connected and some time these are connected by the

power supply.

Fig 4.1.2: INTERFACING OF AT89s52 WITH 16X2 LCD DISPLAY.

4.2 INTERFACING OF SWITCHES

As described above, 12 push button tact switches

have been used, each having 2 legs. To interface it

with microcontroller one leg of all the switches is

connected to ground and the other leg is connected

to microcontroller i.e. pins of port1 and port 3 as

shown in the Fig 4.2.1. The 12 I/O pins of the micro-

controller are made normally high,; when a switch is

press a low appears at the pin. This makes the microcontroller to detect that a

switch has been pressed.

47

LCD 16X2

Fig 4.2.1: Interfacing of switches

4.3 INTERFACING OF RESET SWITCH:Pin 9 of the microcontroller is connected to the reset circuit. Reset circuit con-

sists of a resistor, switch and a capacitor as shown in Fig.4.3.1 When power

supply is given to the AT89s52 microcontroller, it doesn’t start. So to ON the

microcontroller, it needs to be reset. Resetting of microcontroller requires giv-

ing ‘logic 1’ to the reset pin for at least 2 clock pulses.

When power supply is given to the circuit, it makes the capacitor to charge. On

pressing the reset switch current follows through the alternative path via the

switch and makes pin 9 high in addition to this capacitor also discharges with

the help of resistor and help in making the pin 9 high.

48

Fig 4.3.1. INTERFACING MICROCONTROLLER WITH RESET SWITCH.

4.4 INTERFACING OFCRYSTAL OSCILLATOR

To interface crystal oscillator with the microcontroller Pin no 18 and 19 is con-

nected to external crystal oscillator to provide a clock to the circuit. Two capaci-

tors of 33 pf are also applied to the crystal oscillator circuit as shown in Fig

4.4.1. to make it free from noise.

Fig. 4.4.1. INTER-FACING OF CRYSTAL OSCILLATOR WITH MICROCONTROLLER4.5. INTERFACING OF OUTPUT LED

As described above LED has been used for output. For interfacing it with

AT89s52 microcontroller pin no.21 is used as shown in Fig. 4.5.1. The voltage

across the LED is very insensitive to (i.e., very close to constant with) the cur-

49

P9 AT89s52

1918

rent through the device. This means that to a good approximation, we can model

the LED as a constant voltage drop.

If we want to model the LED's V-I characteristics more accurately, then we

could do that as a series combination of an ideal diode and a resistor. The ideal

diode has an exponential V-I characteristic; that is what is responsible for the

non-linear part of the curve near 1.6 V. There is also an ohmic (i.e., linear rela-

tionship between V and I) resistance associated with the LED; the voltage

dropped by that resistance is negligible at small currents, because V = IR is

small when I is small, but becomes significant at higher currents.

Fig.4.5.1 INTERFACING OF MICROCONTROLLER WITH O/P LED.

CHAPTER 5

50

AT89s52

P21

PROGRAMMING OF MICROCON-

TROLLER

51

5.1 KEIL SOFTWARE

As described above, keil software has been used for coding. Keil devel-

opment tools for the 8051 Microcontroller Architecture support every

level of software developer from the professional applications engineer to

the student just learning about embedded software development.

Keil was founded in 1982 by Günter und Reinhard Keil, initially as a

German GBR. In April 1985 the company was converted to Keil Elek-

tronik GMBH to market add-on products for the development tools pro-

vided by many of the silicon vendors. Keil implemented the first C com-

piler designed from the ground-up specifically for the 8051 microcon-

troller.

The industry-standard Keil C Compilers, Macro Assemblers, Debuggers,

Real-time Kernels, Single-board Computers, and Emulators support all

8051 derivatives.

The Keil 8051 Development Tools are designed to solve the complex

problems facing embedded software developers.

When starting a new project, simply select the AT89s52 microcontroller

from the Device Database and the µVision IDE sets all compiler, assem-

bler, linker, and memory options.

The Keil µVision Debugger accurately simulates on-chip peripherals of

microcontroller. Simulation helps in understanding hardware configura-

tions and avoids time wasted on setup problems. Additionally, with simu-

52

lation, one can write and test applications before target hardware is avail-

able.

To begin testing your software application with target hardware, use the

MON51, MON390, MONADI, or FlashMON51 Target Monitors, the

ISD51 In-System Debugger, or the ULINK USB-JTAG Adapter to down-

load and test program code on the target system.

The snap shot of keil µ vision 2 is shown in Fig.5.1.1.

Fig. 5.1.1: Keil snapshot

5. 5.2 PROGRAMMING AT89s52 IN DIGITAL LOCK SYSTEM.

53

/*HEADER FILES*/

#include<reg51.h>

#include<string.h>

/*LCD PIN CONNECTIONS*/

#define lcd P0

sbit rs=P0^1;

sbit en=P0^3;

/*LCD FUNCTIONS DECLARATIONS*/

void init_lcd(void);

void cmd_lcd(unsigned char);

void data_lcd(unsigned char);

void str_lcd(unsigned char *);

void Delay_ms(unsigned int);

/*KEYPAD PIN CONNECTIONS*/

sbit row0=P2^3;

sbit row1=P2^5;

sbit row2=P2^6;

sbit row3=P2^0;

sbit col0=P2^4;

sbit col1=P2^2;

sbit col2=P2^1;

/*MOTOR PIN CONNECTIONS*/

sbit M1=P1^0;

sbit M2=P1^5;

sbit BUZZER=P1^2;

54

/*VARIABLES DECLARATION*/

unsigned char i,j;

unsigned char colval,rowval,pwdchange;

unsigned char pwd[15],str1[]="12345";

unsigned char keypad[4][3]={'1','2','3',

'4','5','6',

'7','8','9',

'*','0','#',};

/*PASSWORD FUNCTION DECLARATION*/

void password(void);

/*KEYPAD FUNCTION DECLARATION*/

unsigned char key(void);

/*MAIN FUNCTION*/

main()

{

unsigned char k=0;

BUZZER=0;

M1=M2=0;

init_lcd(); //LCD INITIALIZATION FUNCTION CALLING

str_lcd("ENTER PASSWORD:"); //DISPLAY STRING ON LCD

while(1)

{

cmd_lcd(0xc0); //2ND LINE DISPLAY

password(); //PASSWORD FUNCTION CALLING

55

if(pwdchange)

{

pwdchange=0;

continue;

}

if(!strcmp(str1,pwd)) //COMPARING WITH 1ST PASS-

WORD

{

BUZZER=0;

cmd_lcd(0xc0);

str_lcd("DOOR OPEN");

M1=0;

M2=1;

Delay_ms(30); //30 MILLISECONDS DE-

LAY

cmd_lcd(0xc0);

str_lcd(" ");

M1=0;

M2=0;

Delay_ms(1500);

cmd_lcd(0xc0);

str_lcd("DOOR CLOSE");

M1=1;

M2=0;

Delay_ms(30);

cmd_lcd(0xc0);

str_lcd(" ");

56

M1=0; M2=0;

k=0;

}

else

{

strcpy(temp,pwd);

cmd_lcd(0x01);

str_lcd("Confirm Password");

cmd_lcd(0xc0);

password();

if(!strcmp(temp,pwd))

{

strcpy(str1,temp);

cmd_lcd(0x01);

str_lcd("Password‘Changed");

}

Delay_ms(1000);

cmd_lcd(0x01);

str_lcd("Enter Pass word");

cmd_lcd(0xc0);

pwdchange=1;

return;

}

else

{

cmd_lcd(0x01);

str_lcd("Password Error");

Delay_ms(1000);

cmd_lcd(0x01);

57

str_lcd("Enter Password");

cmd_lcd(0xc0);

pwdchange=1;

return;

}

}

Else

{

cmd_lcd(0x01);

str_lcd("Password Error");

Delay_ms(1000);

cmd_lcd(0x01);

str_lcd("Enter Password");

cmd_lcd(0xc0);

pwdchange=1;

return;

}

}

else goto label;

}

else goto label;

}

else

{

label:pwd[i++]=j;

data_lcd('*');

}

}

pwd[i]='\0';

}

58

CHAPTER 6BIBLIOGRAPHY

59

BIBLIOGRAPHY

Reference Books

1. The 8051microcontroller and embedded systems:MUHAMMAD ALI MAZIDI, JANICE GILLISPIE MAZIDI

2. The 8051 microcontroller: KENNETH J. AYALA

Website

1. www.8051projects.info

2. www.datasheets4u.com

3. www.8051.com

4. http://www.atmel.com

5. http://www.semiconductors.philips.com

2