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Transcript of 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