microcontroller based digital lock system

7/29/2019 Microcontroller Based Digital Lock System

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Preface

Engineering is not only a theoretical study but it is an implementation of

all we study for creating something new and making things more easy and

useful through practical study. It is an art, which can be gained with

systematic study, observation and practice. In the college curriculum we

usually get the theoretical knowledge of industries and a little bit of

implementation knowledge that how it works? But how can we prove our

practical knowledge to increase the productivity or efficiency of the

industry?

To overcome such problem I the student of Govt. vit(east),jaipur am

supposed to deliver a project on Microcontroller Based DigitalLock

System.


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INTRODUCTION

Security is a prime concern in our day-to-day life. Everyone wants to be as much

secure as possible. The building security is being designed to reduce the amount of stolen

equipment from the building. As we know that theft and robbery are increasing day by day

because manual lock are quit safe and easily be broken by the thief. So a new approach is

needed to overcome the problem.

It makes use of password for user authentication along with a locking system on the

doors to allow entry authentication along with a locking system on the doors to allow entry

only to authorized person. The doors open from the inside without authentication forcompliance with fire codes and for an acceptable level of usability. For ease of application

the authentication is transmitted wirelessly throughout the building from door unit to

authentication unit.

Digital lock is one of a way to solve this kind of problem. The microcontroller based

digital lock for doors is an access control system control system that allows only authorized

persons to access a restricted area. The system is fully controlled by the 6bit microcontroller

AT89C51 which has a 4KB of ROM for the program memory. The password is stored in the

microcontroller so that we can change it at any time. The person who wants to enter has to

enter the correct password.

Digital lock which incorporates a digital programmable micro processing interface

capable of user programming whereby a programmed combination opens the lock. According

to one embodiment of the lock, there can be as many as approximately 720 possible different

combinations which may be entered by the user.

The operation of the lock is driven by an electrical signal derived from the

combination and that electrical signal is sent to a motor assembly inside the lock body in

response to which there is a disengagement of a set of locking bar assistance of a springing

mechanism causes the locking device to open automatically. The doors open from the inside

without authentication for compliance with fire codes and for n acceptable level of usability.


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Front Panel Diagram


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Block Diagram


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Overview of Project

In our project (Microcontroller Based Digital Door Lock) we are going

to lock the door digitally in which a digital programmable micro processing

inter face capable of user programming where by a programmed combination

opens the lock.

Here we use assembly language for coding in microcontroller IC 89C51.

by using this circuit and coding we can also control the electrical equipments to

turn ON and OFF for a fixed time. This project has two control sections which

are microcontroller section and relay section.

Microcontroller Section:-

This section includes the coding of the circuit in which the codes or password is

already stored in it which is known by the owner. This section also provides the

delay timing and number of attempts which can further be changed any time in

the programming.

Derive Section:-

This section includes a motor driven IC L293D. It will drive the motor in

clockwise or in anticlockwise direction so that the door will open and closed

respectively with the motion of the motor.


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Circuit Diagram


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Working

Power supply should always on for this device & connection of alarm is also required.

Firstly enter the valid 6 bit digital codes with the help of 4X3 matrix keyboard. The LCD will

not show the digit which will enter by the owner in place of the 6 bit code it will display

(******), so can no one will see the code entered.

If we press a wrong digit then * button is there in the 4X3 matrix keyboard to change

this particular digit. After entering the perfect code press # key which work as enter key to

give the code. If the code is correct as the password stored in the microcontroller IC then the

motor will turn on and this motor will rotate anticlockwise and hence the door will open.

After a specific delay time the door will automatically closed.

If we dial a code which is not fully matched with code stored in the microcontroller

IC, the LCD will display wrong code and a alarm will ringing. Near the micro controller one

reset switch (a tactile switch) is given which will reset all the systems in digital door lock

system or we say that a digitalized security system


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List of Components Used

Quantity

1. Microcontroller IC 89C51 12. Motor Drive IC L293D 13. Regulator IC 7805 14. Crystal Oscillator 12 MHz 15. Bridge Rectifier 16. Transistor BC 547/548 NPN 17. 4 X 3 Matrix Keypad 18. 16 X 2 Matrix LCD Display 19. Resistors

a. Preset 10K 1b. Resistor Array 10K 1c. 8.2K, 4.7K, 1K (Ceramic 1

10.Capacitorsa. Electrolytic 33pf 2

.01f 2

b. Ceramic 10f 11000f 1

11.Transformer 12V (-6V to 6V) 112.Geared Motor 45 rpm 113.Buzzer 114.Tactile Switch 1


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Details of Components

(1)

Microcontroller IC 89C51

DESCRIPTION

The 89C51/89C52/89C54/89C58 contains a non-volatile FLASH program memory

that is parallel programmable. For devices that are serial programmable (In System

Programmable (ISP) with a boot loader), see the 89C51RC+/89C51RD+ datasheet.

Both families are Single-Chip 8-bit Microcontrollers manufactured in advanced

CMOS process and are derivatives of the 80C51 microcontroller family. All the devices have

the same instruction set as the 80C51.

FEATURES

1. 80C51 Central Processing Unit2. On-chip FLASH Program Memory3. Speed up to 33 MHz4. Full static operation5. RAM expandable externally to 64 k bytes6. 4 level priority interrupt7. 6 interrupt 8-bit I/O ports8. Full-duplex enhanced UART9. Framing error detection

10. Automatic address recognition11. Power control modes12. Clock can be stopped and resumed13. Idle mode14. Power down mode15. Programmable clock out16. Second DPTR register17. Asynchronous port reset18. Low EMI (inhibit ALE)19. 3 16-bit timers20. Wake up from power down by an external interrupt


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Block Diagram of IC 89C51


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Pin Diagram of IC 89C51


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PIN DISCRIPTION

Ground: 0 V reference.

Power Supply:This is the power supply voltage for normal, idle, and power-down operation.

Port 0:

Port 0 is an open-drain, bidirectional I/O port. Port 0 pins that have 1s written to them

float and can be used as high-impedance inputs. Port 0 is also the multiplexed low-order

address and data bus during accesses to external program and data memory. In this

application, it uses strong internal pull-ups when emitting 1s.

Port 1:

Port 1 is an 8-bit bidirectional I/O port with internal pull-ups. Port 1 pins that have 1s

written to them are pulled high by the internal pull-ups and can be used as inputs. As inputs,

port 1 pins that are externally pulled low will source current because of the internal pull-ups.

T2 (P1.0):

Timer/Counter2 external count input/clock out (see Programmable Clock-Out).

T2EX (P1.1):

Timer/Counter2 reload/capture/direction control.

Port 2:

Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. Port 2 pins that have 1swritten to them are pulled high by the internal pull-ups and can be used as inputs. As inputs,

port 2 pins that are externally being pulled low will source current because of the internal

pull-ups. Port 2 emits the high-order address byte during fetches from external program

memory and during accesses to external data memory that use 16-bit addresses. In this

application, it uses strong internal pull-ups when emitting 1s. During accesses to external data

memory that use 8-bit addresses port 2 emits the contents of the P2 special function register.

Port 3:

Port 3 is an 8-bit bidirectional I/O port with internal pull-ups. Port 3 pins that have 1s

written to them are pulled high by the internal pull-ups and can be used as inputs. As inputs,

port 3 pins that are externally being pulled low will source current because of the pull-ups.Port 3 also serves the special features of the

89C51/89C52/89C54/89C58, as listed below:

RxD (P3.0): Serial input port

TxD (P3.1): Serial output port

INT0 (P3.2): External interrupt

INT1 (P3.3): External interrupt

T0 (P3.4): Timer 0 external input

T1 (P3.5): Timer 1 external input

WR (P3.6): External data memory writes strobe

RD (P3.7): External data memory read strobe


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Reset:

A high on this pin for two machine cycles while the oscillator is running, resets the

device. An internal diffused resistor to VSS permits a power-on reset using only an external

capacitor to VCC.

Address Latch Enable:Output pulse for latching the low byte of the address during an access to external

memory. In normal operation, ALE is emitted at a constant rate of 1/6 the oscillator

frequency, and can be used for external timing or clocking. Note that one ALE pulse is

skipped during each access to external data memory. ALE can be disabled by setting SFR

auxiliary.0. With this bit set, ALE will be active only during a MOVX instruction.

Program Store Enable:

The read strobe to external program memory. When executing code from the external

program memory, PSEN is activated twice each machine cycle, except that two PSEN

activations are skipped during each access to external data memory.

PSEN is not activated during fetches from internal program memory.

External Access Enable/Programming Supply Voltage:

EA must be externally held low to enable the device to fetch code from external

program memory locations 0000H to the maximum internal memory boundary. If EA is held

high, the device executes from internal program memory unless the program counter contains

an address greater than 0FFFH for 4 k devices, 1FFFH for 8 k devices, 3FFFH for 16 k

devices, and 7FFFH for 32 k devices. The value on the EA pin is latched when RST is

released and any subsequent changes have no effect. This pin also receives the 12.00 V

programming supply voltage (VPP) during FLASH programming.

Crystal 1:

Input to the inverting oscillator amplifier and input to the internal clock generator

circuits.

Crystal 2: Output from the inverting oscillator amplifier.


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FLASH EPROM MEMORY

General Description

The 89C51/89C52/89C54/89C58 FLASH reliably stores memory contents even after 100erase and program cycles. The cell is designed to optimize the erase and programming

mechanisms. In addition, the combination of advanced tunnel oxide processing and low

internal electric fields for erase and programming operations produces reliable cycling.

Features

1. FLASH EPROM internal program memory with Chip Erase2. Up to 64 k byte external program memory if the internal program memory is disabled

(EA = 0)

3. Programmable security bits4. 100 minimum erase/program cycles for each byte5. 10 year minimum data retention6. Programming support available from many popular vendors.OSCILLATOR CHARACTERISTICS

XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier. The

pins can be configured for use as an on-chip oscillator. To drive the device from an external

clock source, XTAL1 should be driven while XTAL2 is left unconnected. There are no

requirements on the duty cycle of the external clock signal, because the input to the internal

clock circuitry is through a divide-by-two flip-flop.

However, minimum and maximum high and low times specified inthe data sheet must be

observed.

RESET

A reset is accomplished by holding the RST pin high for at least two machine cycles (24

oscillator periods), while the oscillator is running. To insure a good power-on reset, the RST

pin must be high long enough to allow the oscillator time to start up (normally a few

milliseconds) plus two machine cycles. At power-on, the voltage on

VCC and RST must come up at the same time for a proper start-up.

Ports 1, 2, and 3 will asynchronously be driven to their reset condition when a voltage above

VIH1 (min.) is applied to RESET.

The value on the EA pin is latched when RST is disserted and has no further effect.


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(2)

Motor Derive IC L293D

Introduction

One of the first realizations in robotics is that making something move isnt an easy task. You

simply cant take a brain circuit and connect it to motor and expect anything to happen.

The motor will simply say HAH! at the puny output signal from the brains, and stay

stationary. What the brain needs is an enforcer. Muscle. Something to convince the motor to

do things the way the brains want it to be done.

There are many ways to strengthen (buffer) a signal so its strong enough to drive a large

load like a motor. Transistors Hebrides circuit, buffer chips, and dedicated motor driving

chips are all suitable candidates, with their own benefits and limitations. For our Secret

motor driver, we wanted something that would take standard TTL (well, CMOS too) inputsand make a standard servo our slave. You see, standard servos use a Pulse WidthModulated (PWM) signal to tell a servo where to rotate to.

PWM works by sending a rapid train of high/low signals to the servos regular driver brains,

and depending on how different the high signal is from the low signal, the servo moves to the

according position. PWM is great if you dont want to rotate much more than 180, which is

fine for actuators, but not for driving wheels.

With our Secret motordriver and a bit of servo hacking, were going to lobotomize and turn

a standard servo into something more useful - a small, compact, powerful gear motor! Itll be

something you can use very simple input signals to control its rotation. Well even throw in a5V regulator hack if you want to clamp the voltage right at the servo. Or, modify it for use on

abreadboard, which will make good use of the drivers indicatorLEDs to show direction of

rotation.


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Description

The L293D is a 16-pin chip with a little notch cut out of the front of it (that last bit is for you

non-experts). Orient the chip so its notch matches the notch in the shape of the chip on the

PCB. Carefully drop the chip into the gold-plated (pretty uptown, eh?) pads, and solder it into

place from the other side.

To avoid any nasty punctures, clip off any excess pins that poke through the pads on the

solder side.

Usage

So you want to know how to use it? It aint too difficult. Heres the long and short of it: Red -

Vcc (+) Blue - Gnd (-) (on the opposite side of the cable) Orange & Green - D1 & D2

(direction power flow of motor outputs) Yellow - Enable (turns the chip off - connect to gnd

to turn it off).

Connect the red (+) and blue (-) to power. Leave the yellow line alone, unless if you want

to turn the chip off, or pulse it to slow the motor down (a technique called Pulse Width

Modulation). Connect D1 to 5V, D2 to gnd, and the motor will turn one way. Connect D1 to

gnd, and D2 to 5V, and the motor turns the way. Connect D1 D2 to either 5V or gnd, and themotor is in brake mode (try turning it - hard to do, eh?).

Connect the yellow line to gnd, and it doesnt matter what D1 and D2 are connected to, as the

motor is in coast mode, as if it werent connected to the motor driver board at all!


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SGS Thompson Datasheet Characteristics

Logic / Motor supply maximum voltage . . . . . . . . . . . . . . . . . . . . . . 4.5V to 36VInput & enable line voltage range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7V

Peak output current (no repetitive), t


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(3)

Regulator IC 7805

Description

Avoltage regulator (also called a regulator) with only three terminals appears to be a simple

device, but it is in fact a very complex integrated circuit. It converts a varying input voltage

into a constant regulated output voltage. Voltage regulators are available in a variety of

outputs like 5V, 6V, 9V, 12V and 15V.

The LM78XX series of voltage regulators are designed for positive input. For applications

requiring negative input, the LM79XX series is used. the pin configuration of a 5V 7805

regulator.

The output voltage of a regulator circuit can be increased DR MAHESH N. JIVANI ANDDR NIKESH A. SHAH S.C. DWIVEDIby using a pair of voltage-divider resistors. It is notpossible to obtain a voltage lower than the stated rating. You cannot use a 12V regulator to

make a 5V power supply, but you can use a 5V regulator to make a 12V supply. Voltage

regulators are very robust.

These can withstand over-current draw due to short circuits and also over-heating. In both

cases, the regulator will cut off before any damage occurs. The only way to destroy a

regulator is to apply reverse voltage to its input. Reverse polarity destroys the regulator

almost instantly. The circuit for increasing the output voltage of a regulator circuit using a

pair of voltage-divider resistors. Lets assume the value of R1 as 470 ohms, which means that

a constant current of 10.6 mA will be available between terminals 2 and 3 of 7805. Thisconstant current plus the regulator standby current of about 2.5 mA will flow through R2 to

ground regardless of its value. Because of this constant 13.1mA current, R2 can now be set to

a value that will give constant 7 volts across resistor R2. A resistor value of 533 or 510 ohms

(standard value) will give the necessary 7 volts.

With 5 volts across R1 and 7 volts across R2, a total of about 12 volts (regulated) will appear

across terminal 2 and ground. If a variable resistor is used as R2, the output voltage can be

easily fine-tuned to any value greater than 5 volts. The standby current will vary slightly in

the regulator 7805, but 2.5 mA will yield good results in the calculations. If an exact voltage

(within 0.3 volt) is needed, R2 must be a variable resistor.

To make any fixed regulator adjustable, use the following formula: where Vout is the desired

output voltage, Vfixed is the fixed voltage of the IC regulator (5 volts) and Istandby is the

standby current of the0 regulator (2.5 mA). For resistor R1, use any value from 470 ohms to 1

kilo-ohm for best results. For variable resistor R2, put any value from the table given here for

desired voltage operation

the circuit of a 6V- 12V variable power supply using a 5V regulator. The 220V AC mains

voltage is stepped down by transformer X1 to 9 volts, rectified by Pin configuration of 7805

regulator. Circuit for increasing the output voltage Circuit of variable power supply using a

5V regulator


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Features

1. Output Current up to 1A

2. Output Voltages of 5, 6, 8, 9, 10, 12, 15, 18, 24V

3. Thermal Overload Protection

4. Short Circuit Protection

5. Output Transistor Safe Operating Area Protection

FIGURE 34 :VARIOUS ICS


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(4)

Crystal Oscillator 12 MHz

DescriptionA simplified schematic of the oscillator circuit used in Chrontel products. Note that the

typical 2-pin crystal has been replaced by its equivalent circuit model.

Co is the pin-to-pin capacitance. Its value is associated with the crystal electrode design and

the crystal holder.

Rs is the motion resistance. Its value is specified by the crystal manufacturer.

Cs is the motion capacitance and Ls is the motion inductance, which are not specified, and

are functions of the crystal frequency.

Rbias is a feedback resistor, implemented on-chip in Chrontel products, which provides DC

bias to the inverting amplifier.

C1 and C2 are total capacitance-to-ground at the input and output nodes of the amplifier,respectively. If external capacitance is not added, the values of the internal capacitance C1

and C2, including pin parasitic capacitance, are each approximately 15pF to 20pF.


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Crystal Specifications

The reference frequencies for Chrontel's products are derived from an on-chip Pierce

oscillator with an external crystal. The oscillator has been designed to function reliably with

crystals that conform to the following specifications:

Series and Parallel Resonance

here is no such thing as a series cut crystal as opposed to a parallelcut crystal. The samecrystal can be made to oscillate in series resonance mode or parallel resonance mode. The

frequency of oscillation of a crystal is usually specified by the manufacturer as either the

series resonance frequency or the parallel resonance frequency. A crystal can oscillate in

series resonance, meaning that Ls is resonating with Cs, and the resonance frequency.

Some oscillator circuits are designed for series resonance and the oscillation frequency shall

equal the specified series resonance value. These series mode oscillators, however, are more

sensitive to temperature and component variations. In fact, most crystals oscillators in today's

ICs are of the parallel resonance type. The oscillation frequency of a parallel mode oscillator

is always higher thanfseries. The actual oscillation frequency of a parallel mode oscillator is

dependent on the equivalent capacitance seen by the crystal.

At parallel resonance, the crystal behaves inductively and resonates with capacitance

shunting the crystal terminals. Depending on the application, especially in microprocessors

where Pierce oscillators are used predominantly, a crystal manufacturer may specify parallel

resonance frequency instead of series resonance frequency. Sincefparallel is a function of the

load capacitance Ceq, it should also be specified along withfparallel.

For PC CPU clock and VGA clock applications, the frequency accuracy required is usually

not very stringent and can easily be satisfied with a 14.318 MHz crystal that has been

specified for operation in either series or parallel resonance modes.


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Crystal Power Dissipation

This is one of the more important specifications for a crystal. In operation, if the power

dissipated in the crystal exceeds the specified drive level, the crystal may have long termreliability problems. The oscillation frequency may shift from the desired value, and in

extreme cases the crystal may crack and stop oscillating altogether. For the circuit, crystal

dissipation is given by Using typical values for Rs, Ceq and V equals 5V, P equals

approximately 876 W.

Since increasing the value of C1 and C2 would result in increased power dissipation in the

crystal, it is not recommended that extra capacitance be added to pins XTAL1 and XTAL2 of

the clock chip unless it is absolutely necessary to tune the frequency to a desired value. In the

case that additional capacitances are added, a crystal with a higher drive level should be

chosen according to the above equation.

Pullability and Cs

Most crystal manufacturers do not specify Cs explicitly. However, one can measure Cs

indirectly by measuring the change in frequency for a given change in load capacitance. Cs is

related to the crystal pullability by the following equation.

One can reduce the frequency of oscillation by adding external capacitance to C1 and C2 in

equal amounts. The oscillation frequency is given by equation 2. Again, by increasing the

value of C1 and C2, power dissipation of the crystal increases according to (4).

Oscillator Startup Time and PLL Lock Time

Oscillator start-up time is primarily a function of the size of the inverting amplifier. Measured

oscillator startup time is about 1 ms for Chrontels clock chips. PLL lock time is a function of

the PLL unity gain frequency and the frequency spanned in the measurement. Lock time for

Chrontels PLL with internal loop filter is typically in the range of 5 to 20 ms for frequency

to span from 0 Hz to 100 MHz. PLLs with external loop filters will have a longer lock time,

depending on the external filter capacitor value.

By adding the oscillator start-up time and PLL lock time, Chrontels clock chips typicallyreach their final stable frequency in less than 20 ms. In PC applications, this total start-up

time is much less than the time required for the system to reach Power Good, which is well

over 100 ms.


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Bridge Rectifier

A bridge rectifier can be made using four individual diodes, but it is also available in specialpackages containing the four diodes required. It is called a full-wave rectifier because it uses

all the AC wave (both positive and negative sections). 1.4V is used up in the bridge rectifier

because each diode uses 0.7V when conducting and there are always two diodes conducting,

as shown in the diagram below.

Bridge rectifiers are rated by the maximum current they can pass and the maximum reverse

voltage they can withstand (this must be at least three times the supply RMS voltage so the

rectifier can withstand the peak voltages). Please see the Diodes page for more details,

including pictures of bridge rectifiers.

Alternate pairs of diodes conduct, changing over the connections so the alternating directionsof AC are converted to the one direction of DC.

BRIDGE RECTIFIER

OUTPUT WAVEFORM


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Smoothing

Smoothing is performed by a large value electrolytic capacitor connected across the DC

supply to act as a reservoir, supplying current to the output when the varying DC voltage

from the rectifier is falling. The diagram shows the unsmoothed varying DC (dotted line) and

the smoothed DC (solid line). The capacitor charges quickly near the peak of the varying DC,and then discharges as it supplies current to the output.

OUTPUT WAVEFORM

Note that smoothing significantly increases the average DC voltage to almost the peak value

(1.4 RMS value). For example 6V RMS AC is rectified to full wave DC of about 4.6V

RMS (1.4V is lost in the bridge rectifier), with smoothing this increases to almost the peak

value giving 1.4 4.6 = 6.4V smooth DC.

Smoothing is not perfect due to the capacitor voltage falling a little as it discharges, giving a

small ripple voltage. For many circuits a ripple which is 10% of the supply voltage is

satisfactory and the equation below gives the required value for the smoothing capacitor. Alarger capacitor will give fewer ripples. The capacitor value must be doubled when

smoothing half-wave DC.

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

voltages. They are also rated by the maximum current they can pass. Negative voltage

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

automatic protection from excessive current ('overload protection') and overheating ('thermal

protection').

Many of the fixed voltage regulator ICs has 3 leads and look like power transistors, such as

the 7805 +5V 1A regulator shown on the right. They include a hole for attaching a heatsink if

necessary.


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Transistor BC 547/548 NPN

The transistor performs two basic functions.

It acts as a switch turning current on and off. It acts as a amplifier.

This makes an output signal that is a magnified version of the input signal. Transistors come

in several sizes depending on their application. It can be a big power transistor such as is used

in power applifiers in your stereo, down to a surface mount (SMT) and even down to .5microns wide (I.E.: Mucho Small!) such as in a microprocessor or Integrated Circuit.

NPN Transistor: Bipolar junction perform the function of amplifications where a small

varying voltage or current applied to the base (the lead on the left side of the symbol) is

proportionately replicated by a much larger voltage or current between the collector and

emitter leads. Bipolar junction refers to sandwich construction of the semiconductor, where a

wedge of "P" material is placed between two wedges of "N" material. In this NPN

construction a small base current controls the larger current flowing from collector to emitter

(the lead with the arrow).The useful dynamic range extends to 100mA as a switch and to100MHz as an amplifier.

Absolute Maximum Ratings


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Electrical Characteristics


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4 X 3 Matrix Key Board

Description

Once you add a keyboard for your system, you allow the user to input information to the

microcontroller in real time. In this tutorial, you will learn how to connect a keyboard to your

microcontroller and the basic principle to decode keyboard input.

In general, keyboards are organized as a matrix of rows and columns; two side of this matrix

are connected to Vcc through resistors while the third side is connected to the microcontroller

port and configured as an output; and the last side is connected to the microcontroller port

and configured as an input as shown in fig. 1.

Microcontroller keep scanning the keyboard, when all inputs are high ("ones") that mean no

key is pressed; if one bit is low ("zero") that mean there is a pressed key. System designer

setup a Look-Up Table contain the ASCII code for each key, in this project we will use 16

keys to represent the hex number from 0 to F arranged according to keyboard arrangement.

To detect which key is pressed; microcontroller ground all rows, then reads all columns, if allthe columns=1's no key is pressed, if one columns=0 it's indicate that a key is pressed. To


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identify the exact pressed key, microcontroller will start with the top row by grounding it;

then read the columns. If the data read is all ones, no key that row activated, and the process

will move to the next row, until reach the row that has a pressed key. At this stage,

microcontroller knows the row that has a pressed key, and can setup the starting address in

the look-up table for that row.

The last step is finding the column that has a pressed key by rotating the columns bits; one bit

at a time to locate a low bit, the most efficient way is rotating column bits through the carry

flag by using RRC instruction. When the 0 bit found, microcontroller pulls the corresponding

code from the look-up table.

To be sure that no key is still down from the previous session, microcontroller send 0's to all

rows at on time and check the columns, if all columns are high then the normal scanning

start, otherwise, it will wait until all columns become high.

At the left, you will find the assembly code for scanning 4x4 keyboards, assuming that the

input data will be a hex number form 0 to F, ports P1.0 to P1.3 of the 8051 microcontrollerconnected to rows, P2.0 to P2.3 connected to columns. The pressed key ASCII code will be

stored in A. At the right is the flowchart that describes the code


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16 X 2 LCD Display


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Vcc, Vss, and VEE

While Vcc and Vss provide +5V and ground, respectively, VEE is used for controlling LCD

contrast.

RS - register select:

There are two very important registers inside the LCD. The RS pin is used for their selection

as follows. If RS = 0, the instruction command code register is selected, allowingthe user to

send a command such as clear display, cursor at home, etc. If RS = 1 the data register is

selected, allowing the user to send data to be displayed on the LCD.

R/W - read/write:

Pin Symbol I/O Description

1 GND - Ground

2 Vcc - +5V power supply

3 VEE - Contrast control

4 RS I command/data register selection

5 R/W I write/read selection

6 E I/O Enable

7 DB0 I/O The 8-bit data bus









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R/W input allows the user to write information to the LCD or read information from it. R/W

= 1 when reading; R/W =0 when writing.

E - enable:

The enable pin is used by the LCD to latch information presented to its data pins. When datais supplied to data pins, a high to low pulse must be applied to this pin in order for the LCD

to latch in the data present at the data pins. This pulse must be a minimum of 450 ns wide.

D0D7:

The 8 bit data pins, D0D7, are used to send information to the LCD or read the contents of

the LCDs internal registers.

To display letters and numbers, we send ASCII codes for the letters A Z, a z, and

numbers 09 to these pins while making RS = 1.

There are also instructions 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. Table below lists the instruction

command codes.

Code (hex)Command to LCD Instruction Register

1 Clear display screen

2 Return home

4 Shift cursor to left

5 Shift display right

6 Shift cursor to right7 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 right80 Force cursor to beginning of 1st line

C0 Force cursor to beginning of 2nd line

38 2 lines and 5x7 matrix

We also use RS = 0 to check the busy flag bit to see if the LCD is ready to receive

information. The busy flag is D7 and can be read when R/W =1 and RS = 0, as follows: if

R/W =1, RS =0. When D7 = 1(busy flag = 1), the LCD busy taking care of internal

operations and will not accept any new information. When D7 = 0, the LCD is ready to

receive new information. Note: It is recommended to check the busy flag before writing any

data to the LCD.

(9)


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Resistors

There are three resistors of ceramic type is used in this system i.e. 8.2K, 4.7K & 1K.

According to the circuit requirements we used these resistors in the circuit. One with

Microcontroller in the reset mechanism.

A preset of 10K is also used in the circuit which is used to control the intensity of the wordsdisplay on the LCD display.

A resistor array is used with the output port of the microcontroller used in the LCD data cable

is used to make low signal high at the output. This array is of 10K i.e. 10K resistance each.

(10)

Capacitors

In this system we used two types of capacitors one is ceramic type and another is electrolytic

type.

In ceramic type we used two 33pf and two .01f capacitors.

.01f capacitors are used with regulator IC as standard circuit components.

33pf capacitors are used with Crystal Oscillator.

In electrolytic type we used 10f and 1000f capacitors.

1000f capacitor is used as filter capacitor.

10f capacitor is used with microcontroller IC.

(11)

Transformer

In this circuit we used a transformer which is step down type of 12Vpp (i.e. -6V 06V).

Because we used a mains power supply for our project so that we need 12V dc to operate our

project, so thats why we used this transformer.

(12)


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Geared Motor

Specifications

High efficiency, high quality low cost DC motor with gearbox for robotics applications. Very

easy to use and available in standard size. Nut and threads on shaft to easily connect and

internal threaded shaft for easily connecting it to wheel.

Features

45 RPM 12V DC motors with Gearbox

5kgcm torque3000RPM base motor

6mm shaft diameter with internal hole

125gm weight

Same size motor available in various rpm

No-load current = 60 mA(Max), Load current = 300 mA(Max)

(13)

Buzzer

It is simple buzzer which is used in vehicles as a side indicator. It is look like as followsAnd operates at 5V via transistor output.


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(14)

Tactile Switch

It is a push switch which is used to reset the whole system it is place between the Vcc supply

and the reset pin of the microcontroller.It will directly reset the reset pin when the user required the dimensional representation of the

switch is shown here as follows.


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Soldering & Soldering Procedure

Soldering off by ensuring that all parts you are connecting are clean from dirt and grease also

ensure that the mechanical connection are secure before you apply solder and the parts shouldnot be able to move in relation to each other. Another important point to note is that parts of

the joint to be made must be the same temperature.

To actually solder a joint first apply heat by applying the top of the soldering iron against the

thing you are joining immediately apply solder to the point where the iron is contacting.

Remember you should be heating the joints not the solder.

Feed solder only until there is enough to fill the gap and leave s slight swell. Dont apply too

much solder as it can overflow into other place and cause short circuit. Remove the solder

and the iron smoothly. The whole process should only take two or three second at most avoid

touching the joint until it is cooled

A good solder joint will look shiny and smooth while bad joint always starts from scratch.

Remove the solder you just put on and clean the surface before you start the process again.


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Programming Flow Chart


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FEATURES

1. You can control up to 14 devices. It may be any electric or electronic appliances ordevices with simple to heavy appliances. Each device is given a unique code.

2. It makes accurate switching; any false switching will not open the door.3. This circuit require microcontroller IC, so any one with little knowledge of

programming can construct this circuit.

4. This system reads the entered password which is already present in programming ofmicrocontroller IC and than open the door.

5. This circuit switches OFF after a delay time (you can change this Time inprogramming of IC).

6. Before changing the state of the device we can confirm the present status of thedevice.

7. This circuit gives an acknowledgement tone after switching ON the devices toconfirm the status of the device.

8. You can control devices from local telephone. It can also be controlled by mobile.


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ADVANTAGES

1. THERE IS NO NEED OF ANY TYPE OF HARMFUL RADIATIONS.2. NO NEED OF LIGHT SOURCE LIKE AS LASER.3. THERE IS NO PROBLEM OF RANGE.4. THER IS NO NEED OF SPECIFIED PHONE , WE CAN USE EITHER MOBILE

OR BASIC PHONE.

5. BY USING THIS WE CAN ALSO DETECT THE STATUS OF CONNECTEDDEVICES.

6. HERE WE USED DIFFERENT KEYS FOR SIGNALING PURPOSE BY WHICHWE CAN TRANSMIT ADDITIONAL INFORMATION.

7. THERE IS NO NEED OF EXTERNAL CLOCK BECAUSE THIS HAS IN BUILTCLOCK.

8. HERE WE HAVE DISPLAY UNIT ALSO.9. BY USING THIS WE CAN SAVE MONEY.

DRAWBACKS

1. Easily accessed by person who knows the password of lock which is already presentin the programming.

2. This is entirely depend on mobile or telephone network.3. Power supply for local control circuit should always on either circuit is in working

condition or not.


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CONCLUSION

This project is very useful in organizations where a particular device or system is needed to

be confined to only a few people so that the security of the organization is maintained.

Our project which enables the users to prevent the misuse of the device or system. This

project is made for users and one administrator; parting them no one else will be able to use

the device of 220V.

User has his own password. The device is always available for authentic user. users can

enable the system. Now when a user wishes to make a device run, he will have to give the

particular password accepting which the system will enable him to make a use.

In case the user gives a wrong password three times, the system will display access denied

and start buzzing so user will know that someone is trying to misuse the device.

The administrator only can change the password.

This project is also useful at homes where one does not want their children or servants tounnecessarily use the device of 220V.

APPLICATION

Used for security of high professionals computer. This device can also used for security of person by attaching this device at home. This device can provide security of any system or instrument which work on 220v

(ac). It can be used in the homes also for locking of television so that children cannot use itwithout permission

microcontroller based digital lock system

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