Electronic Safe2

8/10/2019 Electronic Safe2

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ABSTRACT

The safety of life and properties is a very important part of our

everyday life. Bandits and burglars have designed various means

with which they do away with important belongings in the

absence of the owners. One way of guiding against this menace is

the security code locking system which can be mounted on doors

or even electrically operated metal boxes referred to as safes. The

design of electronics to control any automated system is

generally referred to as a code lock mechanism. An application of

code lock mechanism is design of electronic safe using themicrocontroller as an interface as described in this work. The front

panel of the safe is kept as simple as possible for the

understanding of the user. A code locking mechanism that

transmits information between a key and a locking mechanism

secured against interception misuse, but exible with respect to

original euipment, replacement parts, and emergency functions,

is obtained if the key code is, in each case, cryptographically

encoded through a hardware encoder. !hen the locking

mechanism is "rst operated, a control element inductively

coupled to a locking mechanism read#write unit with a new key

once and in a non#over writable manner, transmits an indent

number to the ob$ect memory. The lock used in the

microcontroller based electronic safe is basically a electronic

lock. A electronic lock is a lock that reuires the entering of a

speci"c seuence of symbols to dislodge and open. Though the


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symbols are typically numerical, letters and other types of

symbols may also be used to formulate a seuence.

CHAPTER ONE

INTRODUCTION

Background of the project:

The new %ncyclopaedia Britannica, &'() de"nes code lock as *amechanical device for securing a safe or receptacle so that it

cannot be opened except by the key or a series of manipulations

that can be carried out only by a person knowing the secret or

code+. At this time locks are perceived as mechanical devices that

can be classi"ed into key#operated or electronic lock.

%lectronic safe is simply a mechanism for locking and unlocking

an electronically operated safe with a complicated lock used for

storing valuable things like money, ewels for security purposes. -t

makes use of *code lock+ as a mechanical device. -t is simple and

secure method of locking safe without having to resort to the use

of keys. This is used to secure money and valuables in the sense

that an authoried person in that section will only know the code

lock number.


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The electronic safe is a practical and code locking solution, ideal

for commercial or residential premises. -t removes the need for

keys, taking away the hassle and cost of copying or replacing lost

ones

The microcontroller electronic safe is a secure, lockable box used

for securing valuable ob$ects against theft or damage. -f so, then,

an electronic safe is an electro#mechanical safe operated by

electronics. !hile designing the electronics for the ubiuitous safe

may sound straightforward, it is fraught with its own challenges.This article describes a simple electronics safe design and

discusses design techniues for dealing with challenges range

from preventing an intruder to break into the safe to power

management techniues for consuming the least power. This

article also discusses technological advances that can be used to

move this simple product concept beyond its original traditional

design.

Oject!"e# and I$portance of the De#!gn

-n recent years, a new type of lock, called an /electronic safe

lock/, has been developed for use on safes and vaults. The

electronic safe lock uses a programmable electronic circuit in

addition to mechanical components to control the safe locking

mechanism. The use of a programmable circuit gives the

electronic safe lock the ability to provide a large number of


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features not available in the traditional mechanical safe lock.

These features include0

The ability to provide each user of the safe with a di1erent

electronic . -f an employee who has a electronic to the safe

leaves the company, only his electronic needs to be

changed # no need to change the electronic of the other

users.

%lectronic s can be uickly changed by the owner or

manager of the facility # no need to call in a locksmith tochange the electronic .

2peci"c electronic s can be programmed to only work on

certain days and at certain times. 3or example, an employee

who worked during the day could be given a electronic that

would only open the safe during day shift # her electronic

wouldn4t work during night shift.

An /audit trail/ record is kept in the lock. A report telling who

opened the safe and at what time can easily be created.

The lock can be programmed to provide a time#delay period

between the time when the electronic is entered and the

time when the safe unlocks. This is commonly done to

discourage robberies.

The lock can be programmed to reuire two separate

electronic s be entered in order to open the safe. This is

useful when your company policy reuires that two people

be present any time that the safe is opened.


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%lectronic safe locks are designed as /drop#in/ replacements for

mechanical safe locks. This means that most existing safes can be

euipped with electronic safe locks without reuiring that ma$or

modi"cations be made to the safe. %xtensive e1ort has been put

into the design of electronic safe locks so that they are $ust as

reliable as their mechanical counterparts.

E%ECTRONIC SA&E %OC'S

%lectronic safe locks work by punching a certain electronic intoan electronic keypad which triggers the locking mechanism to

open. 5any prefer these safes since the electronic can be easily

changed, as opposed to key locking mechanisms that are more

di6cult and less secure in the event a key is lost.

!ith electronic safe locks, it makes it easy for a business to

change the electronic if a key employee is terminated, or you

have reason to believe that security may have been breached. -t

can o1er peace of mind, and some business owners change the

electronic safe locks freuently for security purposes.

%lectronic safe locks are great for storing keys, as a matter of

fact, and some people choose electronic safe locks for safes

where they store their laptops, which even have an access to plug

in the electric cord to the laptop, to keep it fully charged.


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There are also electronic safe locks that are "ngerprint activated

and some may have the added security of a seven#day repeating

time lock schedule using secure, encrypted communication

protocol to give direct control over the lock bolt extension and

retraction which is controlled through the electronic safe locks

keypad or touchpad.

They typically have a battery for power and many of them o1er

secure and highly sophisticated features to make them more

desirable and convenient than key lock safes.

%lectronic safe locks o1er the ability to change your electronic s

without paying a locksmith, they might have a time delay, time

delay override, wrong try penalty, duress and alarm feature7 they

are also capable of high technology choices such as management

reset codes, a master code and several user codes and may have

over a million di1erent codes you can choose from.

5ost users prefer them because they allow you to program

di1erent features to "t the purpose you need it for. 2ome of them

have a hold#up alarm, a bolt sensor which tells you when the door

is opened, penalty lockouts for failed attempts and other features

that make them secure and easily programmable. This is why

they are often chosen for small retail businesses or multiple

employee access locations.


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Because they o1er more features that can be set or changed by

the home or business owner, electronic safes are often preferred

for security purposes and ease of programming.

%lectronic safe locks are more secure in the event you lose your

keys, such as car and house keys. -t would at least make it

di6cult for an intruder to break into your house and "nd the key

that would give them access to your valuables such as $ewelry

and cash or important papers.

8ou can easily change the electronic s on electronic safe locks,

which is the primary reason many people prefer them. Besides

the additional features that they are capable of that key safe

locks are not, this ease of control and security falls on the owner4s

freedom to change electronic s or features whenever they choose.

This can save the expense and hassle of a locksmith as well as

the security breach of lost safe keys, which are the primary

reasons people prefer electronic safe safes.

Ho( to )ake a Cheap Safe

There are almost endless ways to make a cheap safe. The

materials you choose vary depending on the items that you want

to keep safe, how large the items are and whether you want the

safe to be portable. -n addition, you can make a sort of a safe that

doesn4t look like a safe.


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9et some sort of metal box if you want to make a safe that

you will likely keep in your house. 9enerally, a metal box is

your best choice. :epending on the sie of the valuables,

look for a metal candy tin, tackle box or other type of box

with a hinged lid. ;inges on the inside of the box rather than

the outside will be the safest choice.

Take the box to a welding service and have them weld a lock

onto the box. This will make it more di6cult for a thief to

break into the safe. 8ou can choose between locks that

reuire a key or use a electronic . This is entirely up to you. -t

will probably depend on whether you are more likely to lose

a key or forget a string of numbers.

:rill at least six holes in the bottom of the box. :rill one hole

in each corner, and two near the middle.


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5ost safe locks that are installed on the safes are actually

mechanical electronic locks. This means that you turn a dial in a

particular way, left and right, matching up numbers, in order for

the safe to open up. The electronic use using a mechanism that

has remained relatively changed since their invention many years

ago.

A key component of the traditional electronic lock is the wheel

pack. There are a number of notched wheels on a spindle. The

spindle is connected on one end to the drive cam. !hen you turnthe dial, you are actually turning the drive cam. This drive cam

has a kind of know that also matches the knob on the last wheel,

called the y wheel. All the wheels correspond with each other

through the drive cam.

The fence that is placed over the wheels is actually a metal bar.

!hen the notches on the wheels line up, this fence >that stopped

the lock from being opened? falls in the gap created by the

alignments of all the wheels. This is what allows the lock to open.

!hile the mechanical electronic lock has severed us well for

many years, it does have its disadvantages. -t is hard to change

and over time dust and wear can make it more di6cult to open

the lock. 3or these reasons, many manufactures and many

customers how look for electronic safe locks.


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The electronic has a digital keypad. The manufacturer sets the

initial electronic for the digital keypad at the factory. !hen you

type in the matching numbers into the keypad the electronic

mechanism unlocks the safe.

There are many reasons why consumers prefer electronic safes

over the manual electronic safes and safes that use metal key0

A critical advantage is that the password is easy to change.

3ollowing simple instructions and using the current password, youcan change the safe to use a new password at any time. This is

especially useful when you want to temporarily give someone

access to the safe. 8ou can set the new password and give it to

the new person. !hen they no longer should have access, you

can change it to something new.

There is typically a backup key to use with electronic safes.

;owever, the key is used only as a back up and is not designed to

be the primary means of opening and closing the safe. 8ou should

store the key in a safe place. @ormally you will use a key

password to open the safe.


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2ome of todays more advance safes allows you to use your

"ngerprint to open the safe. This is a similar technology to the

one build into many laptop computers today.

%lectronic safes o1er great exibility and allow the user to change

the electronic without the expense and hassle of calling a

locksmith. The next time you are looking for a new safe, consider

an electronic safe.

CHAPTER T+O

,-. %ITERATURE RE*IE+

An electronic safe is a type of lock in which a seuence of

numbers or symbols is used to open the lock. The seuence may

be entered using a single rotating dial which interacts with

several discs or cams, by using a set of several rotating discs with

inscribed numerals which directly interact with the locking

mechanism, or through an electronic or mechanical keypad.

3our digit code lock using mobile phone is a type of electronic

lock in which seuence of members are used to open the lock.

The seuence keyed in interacts with the mechanism through

the digital and electronic keypad.


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,-/ HISTOR0

,-, E1ectron!c %ock

%lectronic locks have existed for centuries, but it was not until the

&)CCs that ma$or advancements in this technology were made.

@ow, electronic locks can be purchased at any hardware store or

mass merchandiser. ;owever, it should be remembered that the

locks we take for granted today were developed over centuries of

trial and error.

The earliest electronic safe was excavated in a =oman period

tomb on the Derameikos, Athens. Attached to a small box, itfeatured several dials instead of keyholes.E-n &FC(, the 5uslim

engineer Al#aari documented an electronic lock in his book al#

-lm !al#Amal al#@a" 3i 2ina4at al#;iyal >The Book of Dnowledge of

-ngenious 5echanical :evices?. 5uhammad al#Astrulabi >ca.

&FCC? also made electronic locks, two of which are kept in

Gopenhagen and Boston 5useums.

Ear12 E"!dence of E1ectron!c %ock#

/-The Eureka %ock3 The %ureka lock was patented in &)(F.

The device consisted of an electronic safe with "ve tumblers, and

was once used to lock up a vault in the


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introduced the 5onitor Bank Jock. This lock is historically

signi"cant because it soon became the standard bank lock,

e1ectively replacing locks with keys and making electronic locks

the preferred bank lock. The company is still in operation today.

4- )a#ter %ock3 5aster Jocks are instantly recogniable to

any person who attended high school in the


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But most of the times a land line phone is being used. -f a land

line phone is used then a separate ring detector circuit is reuired

for detecting the number of rings and then picking up the phone.

-t uses an extra relay and we have to enter inside the mechanism

of phone.

-n this report an auto answer facility which is present in many of

the cell phones today has been used, this eliminated the

designing of a ring detector circuit.

The aim of the proposed system is to develop a cost e1ective

solution that will provide controlling of security and to enable

home security against intrusion in the absence of owner. This

system is highly feasible due to development of a low cost

system. This control system with an a1ordable cost was thought

to be built that should be able to provide access via an onboard

keypad in other to automate the conventional electronic lock

system thus allowing for home security.

Pre#ent Scenar!o:

Nossible customers for this product would be home improvement

contractors, and supply stores. The bene"t of this, is that the end#

product can be sold in large uantities and it can be incorporated

into the construction of modernie homeso6cesindustries. The

end#product will not be sold in retails stores because recon"guring

it for proper control will be complicated and should only be


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attempted by trained technicians. =etail stores would also not be

a good target for commercialiation due to the system reuiring a

mobile phone plan in order to operate. Advertising through mobile

phoneproviders would be a more feasible option.

Pre#ent and &uture Scope:

This product is aimed toward average consumers who wish to

control household security out"t remotely from their mobile

phones provided that it is electrically controllable. %xample of

feasible applications under consideration includes7 enabledisablesecurity systems, fans, lights, kitchen appliances, and

heatingventilationair conditioning system.


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CHAPTER THREE

RESEARCH AND DESI9N )ETHODO%O90

RESEARCH )ETHOD

Basically, research on this pro$ect was done both on the internet

and on various %lectrical%lectronic textbooks. 3inally, we arrived

at designing with polished wood and leather applied all round for

proper "nishing. The circuit was built around discrete electronics

components including resistors, capacitors, transistors and as themicrocontroller as the core.

B%OC' DIA9RA) O& THE S0STE)


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B%OC' DIA9RA) DESCRIPTION

'E0 ENCODERS: The key encoders provide all the necessary

logic to fully encode an array of 2N2T switches. The keyboard scan

is implemented internally by the microcontroller which constantly

monitors the individual key that makes up the entire keyboard.

These encoders also have on#chip pull#up devices which permit

switches with up to MCk on resistance to be used.

A :ata Available output goes to a high level when a valid

keyboard entry has been made. The :ata Available output returns

to a low level when the entered key is released, even if another

key is depressed. The :ata Available will return high to indicate

acceptance of the new key after a normal debounce period7 this

two#key roll#over is provided between any two switches. An

internal register remembers the last key pressed even after the

key is released.


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PO+ER SUPP%0 UNIT:the power supply ection is built around a

conventional components and also run directly from a (P:G that

is stabilised down to MP:G for proper operation of the

microcontroller. Below is the power supply circuit when

running from the utility supply.


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As seen on the above "gure, in order to enable microcontroller to

operate properly it is necessary to provide0

Nower supply

=eset signal

Glock signal

Obviously, all this is about very simple circuits, but it does not

have to be always like that. -f device is used for handling

expensive machines or for maintaining vital functions, everything

becomes more and more complicatedQ This kind of solution is

uite enough for the time being. The circuit, shown on the

"gure above, uses cheap voltage stabilisator J5')CM and

provides high#uality voltage level and uite enough current to

enable microcontroller and *peripheral electronics+ to operate

>su6cient current in this case amounts to &A?Q


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*ISUA% DISP%A0 UNIT:The visual display unit is used to show

the current values of number of times attended work by the

workers. -t is built around the microcontroller which serves as the

core for the system by outputting the desired values of

information unto the display.

DC )OTOR UNIT: -n general, :G motors are similar to :G

generators in construction. They may, in fact, be described as

generators *run backwards.+ !hen current is passed through thearmature of a :G motor, a torue is generated by magnetic

reaction, and the armature revolves. The action of the

commutator and the connections of the "eld coils of motors are

precisely the same as those used for generators. The revolution of

the armature induces a voltage in the armature windings. This

induced voltage is opposite in direction to the outside voltage

applied to the armature, and hence is called back voltage or

counter electromotive force >emf?. As the motor rotates more

rapidly, the back voltage rises until it is almost eual to the

applied voltage. The current is then small, and the speed of the

motor will remain constant as long as the motor is not under load

and is performing no mechanical work except that reuired to

turn the armature.


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power from the source supplying it and to do more mechanical

work.

Because the speed of rotation controls the ow of current in the

armature, special devices must be used for starting :G motors.

!hen the armature is at rest, it has virtually no resistance, and if

the normal working voltage is applied, a large current will ow,

which may damage the commutator or the armature windings.

The usual means of preventing such damage is the use of a

starting resistance in series with the armature to lower the

current until the motor begins to develop an adeuate backvoltage. As the motor picks up speed, the resistance is gradually

reduced, either manually or automatically.

The speed at which a :G motor operates depends on the strength

of the magnetic "eld acting on the armature, as well as on the

armature current. The stronger the "eld, the slower is the rate of

rotation needed to generate a back voltage large enough to

counteract the applied voltage. 3or this reason the speed of :G

motors can be controlled by varying the "eld current. -n this

pro$ect, the motor is used to control the sliding gate of the safe so

that it can be controlled via the microcontroller.

)ICROCONTRO%%ER UNT: A microprocessor is not a complete

computer. -t does not contain large amounts of memory or have

the ability to communicate with input devicesRsuch as

keyboards, $oysticks, and miceRor with output devices, such as

monitors and printers. A di1erent kind of integrated circuit, a


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microcontroller, is a complete computer on a chip, containing all

of the elements of the basic microprocessor along with other

specialied functions. 5icrocontrollers are used in video games,

videocassette recorders >PG=s?, automobiles, and other

machines.-n this design the microcontroller unit forms the core of

the system meaning that all necessary mathematical and logical

operation of the system is executed here. -ts function spans

from7 checking the keyboard in order to ascertain if there is a

valid data, outputs the current state of the internal database unto

the display, checks for error, checks for multiple entry, verify userpasswords and functions that panders to the function of the

system.

;ow does microcontroller operateS

%ven though there is a great number of various microcontrollers

and even greater number of programs designed for the

microcontrollers use only, all of them have many things in

common. That means that if you learn to handle one of them you

will be able to handle them all. A typical scenario on whose basis

it all functions is as follows0

&. Nower supply is turned o1 and everything is so stillchip is

programmed, everything is in place, and nothing indicates

what is to come

F. Nower supply connectors are connected to the power supply

source and everything starts to happen at high speedQ The

control logic registers what is going on "rst. -t enables only


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uart oscillator to operate. !hile the "rst preparations are

in progress and parasite capacities are being charged, the

"rst milliseconds go by.

H. Poltage level has reached its full value and freuency of

oscillator has become stable. The bits are being written to

the 23=s, showing the state of all peripherals and all pins are

con"gured as outputs. %verything occurs in harmony to the

pulses rhythm and the overall electronic starts operating.

2ince this moment the time is measured in micro and

nanoseconds.I. Nrogram Gounter is reset to ero address of the program

memory. -nstruction from that address is sent to instruction

decoder where its meaning is recognied and it is executed

with immediate e1ect.

M. The value of the Nrogram Gounter is being incremented by &

and the whole process is being repeated...several million

times per second.


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DECRETE CO)PONENTS DESCRIPTION

RESISTOR

=esistors are one of the most common components in an

electronic circuit. The basic operation is to limit the ow of current

in the circuit. 5any resistor values were used in this pro$ect. 2ome

of them include &DU, &CkU, &CCU and the HHCU used to limit the

current that ows to the seven segment display.

Ho( to read Re#!#tor Co1or Code#

B1ac

k

Bro(

n

Re

d

Orang

e

0e11o

(

9ree

n

B1u

e

*!o1e

t

9re

2

+h!t

e

. / , 4 5 7 ; 6


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3irst "nd the tolerance band, it will typically be gold >MV? and

sometimes silver >&CV?. 2tarting from the other end, identify the

"rst band # write down the number associated with that color7 in

this case Brown is &. @ow 4read4 the next color, here it is Black so

write down a 4C4 next to the six. >you should have 4&C4 so far.? @ow

read the third or 4multiplier exponent4 band and write down that

as the number of eros. -n this example it is two so we get 4&CCC4.

-f the 4multiplier exponent4 band is Black >for ero? don4t write any

eros down.

-f the 4multiplier exponent4 band is 9old move the decimal point

one to the left. -f the 4multiplier exponent4 band is 2ilver move the

decimal point two places to the left. -f the resistor has one more

band past the tolerance band it is a uality band.

BS /6, Cod!ng for re#!#tor "a1ue#

British 2tandard &)MF?. The letter = is used for

Ohms and D for Dohms 5 for 5egohms and placed where the

decimal point would go.

At the end is a letter that represents tolerance !here 5WFCV,

DW&CV, WMV, 9WFV, and 3W&V :W.MV GW.FM BW.&V

&!g /-5=esistor color code


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CAPACITOR

Gapacitors store electric charge. They are used with resistors in

timing circuits because it takes time for a capacitor to "ll with

charge. They are used to smooth varying :G supplies by acting as

a reservoir of charge. They are also used in "lter circuits because

capacitors easily pass AG >changing? signals but they block :G

>constant? signals. There are many types of capacitor but they

can be split into two groups, polaried and unpolarised. %ach

group has its own circuit symbol.

E1ectro12t!c Capac!tor#

%lectrolytic capacitors are polaried and they must be connectedthe correct way round, at least one of their leads will be marked X

or #. They are not damaged by heat when soldering.

There are two designs of electrolytic capacitors7 axial where the

leads are attached to each end >FFCY3 in picture? and radial

where both leads are at the same end >&CY3 in picture?. =adial

capacitors tend to be a little smaller and they stand upright on

the circuit board. -t is easy to "nd the value of electrolytic

capacitors because they are clearly printed with their capacitance

and voltage rating. The voltage rating can be uite low >(P for

&!g /-%lectrolytic


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example? and it should always be checked when selecting an

electrolytic capacitor.

Nonpo1ar!=ed capac!tor#

2mall value capacitors are nonpolaried and may be connected

either way round. They are not damaged by heat when soldering,

except for one unusual type >polystyrene?. They have high

voltage ratings of at least MCP, usually FMCP or so. -t can be

di6cult to "nd the values of these small capacitors because there

are many types of them and several di1erent labeling systemsQ

5any small value capacitors have their value printed but without

a multiplier, so you need to use experience to work out what the

multiplier should be. 3or example C.& means C.&Y3

TRANSISTORS

Transistors are made from semiconductors. These are materials,

such as silicon or germanium, that are *doped+ >have minute

amounts of foreign elements added? so that either an abundance

or a lack of free electrons exists. -n the former case, thesemiconductor is called n#type, and in the latter case, p#type. By

combining n#type and p#type materials, a diode can be produced.

!hen this diode is connected to a battery so that the p#type

material is positive and the n#type negative, electrons are

&!g /-7 @onpolaried Gapacitors


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repelled from the negative battery terminal and pass unimpeded

to the p#region, which lacks electrons. !ith battery reversed, the

electrons arriving in the p#material can pass only with di6culty to

the n#material, which is already "lled with free electrons, and the

current is almost ero.

The bipolar transistor was invented in &KI) as a replacement for

the triode vacuum tube. -t consists of three layers of doped

material, forming two p#n >bipolar? $unctions with con"gurations of

p#n#p or n#p#n. One $unction is connected to a battery so as to

allow current ow >forward bias?, and the other $unction has abattery connected in the opposite direction >reverse bias?. -f the

current in the forward#biased $unction is varied by the addition of

a signal, the current in the reverse#biased $unction of the

transistor will vary accordingly. The principle can be used to

construct ampli"ers in which a small signal applied to the forward#

biased $unction causes a large change in current in the reverse#

biased $unction.

Another type of transistor is the "eld#e1ect transistor >3%T?. 2uch

a transistor operates on the principle of repulsion or attraction of

charges due to a superimposed electric "eld. Ampli"cation of

current is accomplished in a manner similar to the grid control of

a vacuum tube. 3ield#e1ect transistors operate more e6ciently

than bipolar types, because a large signal can be controlled by a

very small amount of energy.


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Transistors function ma$orly as switch or ampli"ers. To function as

a switch, the transistor has to be biased into saturation i.e. the

base voltage exceeds C.'v for silicon type and C.Hv for

germanium type. On the other hand, the base voltage can be

varied continually by an input signal for the transistor to function

as an ampli"er. The transistors in this circuit are all 3ield %1ect

Transistors >3%T? and they function as high speed switches.

DIODE

This is an electronic device that allows the passage of current in

only one direction. The "rst such devices were vacuum#tube

diodes, consisting of an evacuated glass or steel envelope

containing two electrodesRa cathode and an anode. Because

electrons can ow in only one direction, from cathode to anode,

the vacuum#tube diode could be used as a recti"er. The diodes

most commonly used in electronic circuits today are

semiconductor diodes. The simplest of these, the germanium

point#contact diode, dates from the early days of radio, when the

received radio signal was detected by means of a germanium

crystal and a "ne, pointed wire that rested on it. -n modern

germanium >or silicon? point#contact diodes, the wire and a tiny

crystal plate are mounted inside a small glass tube and connected

to two wires that are fused into the ends of the tube.


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S+ITCHES AND PUSHBUTTONS

There is nothing simpler than thisQ This is the simplest way of

controlling appearance of some voltage on microcontrollers input

pin. There is also no need for additional explanation of how these

components operate.

@evertheless, it is not so simple in practice... This is about

something commonly unnoticeable when using these components

in everyday life. -t is about contact bounce# a common problem

with mechanical switches. -f contact switching does not happen so

uickly, several consecutive bounces can be noticed prior to

maintain stable state. The reasons for this are0 vibrations, slight

rough spots and dirt. Anyway, whole this process does not last

long >a few micro# or milliseconds?, but long enough to be

registered by the microcontroller. Goncerning pulse counter, error

occurs in almost &CCV of casesQ


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The simplest solution is to connect simple =G circuit which will

*suppress+ each uick voltage change. 2ince the bouncing time is

not de"ned, the values of elements are not strictly determined. -n

the most cases, the values shown on "gure are su6cient.

*EROBOARD

This work completed by using a Peroboard to assemble the above

explained electronic components. The process described below

was taken, to prepare the Peroboard.

9rab a very sharp craft knife and a ruler. On the track side of theboard, count IC complete holes along a track, then place the ruler

perpendicular to the tracks on the next hole.

@ow turn the board over, and repeat the operation in exactly the

same place on the component side. Nick up the board and snap it

with both hands, keeping your "ngers close to the score mark oneither side # it should break evenly, leaving you with two

rectangular pieces. @ow >if the board is too wide? do the same

thing again, but along the tracks. Gount HK tracks from the edge

then lay your ruler along the ICth track and score through the


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holes on that track. :o the same on the other side, then snap. -f

all went well, you should now have a piece of Peroboard of the

correct sie # HK tracks by IC holes.

In#pect the track#

Pery occasionally, a piece of Peroboard will have defects such as

small splashes of copper bridging ad$acent tracks. -nspect the

board carefully to make sure there are no such bridges. -f you do

"nd one, run your knife between the tracks in order to cut it.

%I9HT>E)ITTIN9 DIODE ?%ED@Jight#emitting diodes are elements for light signaliation in

electronics. They are manufactured in di1erent shapes, colors and

sies. 3or their low price, low consumption and simple use, they

have almost completely pushed aside other light sources# bulbs at

"rst place. They perform similar to common diodes with the

di1erence that they emit light when current ows through them.

-t is important to know that each diode will be immediately

destroyed unless its current is limited. This means that a

conductor must be connected in parallel to a diode. -n order to

correctly determine value of this conductor, it is necessary to


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know diodes voltage drop in forward direction, which depends on

what material a diode is made of and what colour it is. Palues

typical for the most freuently used diodes are shown in table

below0 As seen, there are three main types of J%:s. 2tandard

ones get full brightness at current of FCmA. Jow Gurrent diodes

get full brightness at ten times lower current while 2uper Bright

diodes produce more intensive light than 2tandard ones.

Co1or T2peT2p!ca1current Id?$A@

)a8!$a1current If ?$A@

*o1tage dropUd ?*@

-nfrared # HC MC &.I

=ed 2tandard FC HC &.'

=ed 2uper Bright FC HC &.)M

=ed Jow Gurrent F HC &.'

Orange # &C HC F.C

9reen Jow Gurrent F FC F.&

8ellow # FC HC F.&

Blue # FC HC I.M

!hite # FM HM I.I

2ince the )CM& microcontrollers can provide only low input current

and since their pins are con"gured as outputs when voltage level

on them is eual to C, direct connecting to J%:s is carried out as


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it is shown on "gure >Jow current J%:, cathode is connected to

output pin?.

CHAPTER &OUR

DESI9NIN9 AND I)P%E)ENTATION O& E%ECTRONIC SA&E

The basic feature of any electronic safe is its ability to read an

input information via a medium such as a keypad, then operate

an electronic door to grant access to a particular environment. A

simple circuit to achieve this is illustrated below7


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This circuit is designed to operate an electrical door#release

mechanism which can be incorporated to an electronic safe. To

open or release the door, %nter the four#digit code of your choice #

and the relay will energie for the period of time set by GI Z =I.


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Any keys not wired to /A B G Z :/ are connected to the base of

LF. !henever one of these /!rong/ keys is pressed # LF takes pin

& low and the code entry fails. 2imilarly, if /G/ or /:/ is pressed

out of seuence # LI or LH will take pin & low and the code entry

will fail. -f you make a mistake while entering the code # simply

start again.

The Deypad must be the kind with a common terminal and a

separate connection for each key. On a &F#key pad, look for &H

terminals. The matrix type with ' or ) terminals will @OT do. A &F#key pad has eight /!rong/ keys connected to /%/. -f you need a

more secure code # use a bigger keypad with more /!rong/ keys.

Below is a veroboard layout of the above circuit diagram7


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THE )ICROCONTRO%%ER E%ECTRONIC SA&E5icrocontroller based electronic safe is considered as one of the

best security that you can use for keeping your valuables. An

electronic safe in its basic form is a thick steel box with a thickersteel door. The door closes on to the box with a solid steel bolt.

The bolt may be operated by a knob. A sample electronic safe

interface is shown in 3ig & below.

A keypad is reuired to enter the unlocking code as are a couple

of J%:s to display output and serve as the -O interface. A

mechanical key is provided with many safes for emergency

access when the electronic code is forgotten.

Additional features provided on most electronic safes are low

battery warning, freee on repeated wrong electronic code entry,

and long bu on entering the wrong electronic code. %lectronic

safes are common in hotels as they provide the ability to set and

reset the electronic code for each new guest.

&!g /- E%ock U#er Interface

U#age Scenar!o#

2imple scenarios to describe the operation of an electronic safe

are given below0


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%ock the E1ectron!c Safe-The mechanical knob turned to put

the steel bolt into position and lock the door. The cam mechanism

would be such that turning the knob in the opposite direction is

not going to engage the electronic safe>&!g , e1o(@.

&!g ,- %ock!ng the E1ectron!c Safe

Un1ock the E1ectron!c Safe-The user shall input the electronic

code on the keypad to unlock the electronic safe. On every key

press, a short beep is generated to provide audio feedback to the

user to con"rm that the key was accepted.

-f the user enters a wrong electronic code, then the *%==+ J%:

will light#up to indicate that the code was wrong. A sharp bu is

generated to make this evident to the end user. =epeated wrong

entry will lock the keypad and the electronic safe. The emergency

key must be used to unlock the safe and the electronic code has

to be reset as described below.


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Batter2 D!#charge Cond!t!on- -n case the battery is discharged

completely, the bolt will lock permanently and the emergency key

has to be used to unlock the safe. The *BAT+ J%: will switch on

when the battery is less than a particular level to alert the user to

change the battery.

E1ectron!c Code %o#t- -n case the electronic code is lost, then

the emergency key can be used to unlock the safe.

SetRe>#et E1ectron!c Code- The feature to set or reset the

electronic code will be available only when the safe is open. A

seuence of key presses can open up the microcontroller to set

the new electronic code. The microcontroller saves the electronic

code into its nonvolatile memory.

I$p1e$entat!on of a #afe de#!gn

%arly electronic safe designs used hardware circuits employing

counters to determine the right electronic code. Jater designs

have been based on microcontrollers because of the exibility

o1ered by microcontrollers and software programming.

A block diagram of a microcontroller#based design is shown in 3ig

H below. -t consists of a microcontroller and a motor that is


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powered by the battery. The microcontroller takes inputs via the

keypad and, depending upon the code, will trigger the motor and

the door lock mechanism to move the cam and turn the bolt.

J%:s are triggered based on microcontroller status, battery

condition, and any error while reading the code. An optical ob$ect

sensor is used to detect the condition of the door.

)echan!ca1 Con#truct!on-

Although this is an article on electronics for electronic safe, thesingle biggest consideration for a good and reliable safe is its

mechanical construction. The electronics Nrinted Gircuit Assembly

>NGA? should be behind the solid steel structure.

Any attempt to force open via the front panel through the keypad

should make the contents of the safe accessible. One possible

option is to separate the NGA from the keypad. The NGA should be

behind a solid steel structure while the keypad should be on the

front of the door.

Po(er Ec!enc2-

Nower consumption is the second most important aspect of an

electronic safe. Parious designs can be implemented to save

power such as the use of deep sleep if there is no input from the

keypad for a speci"ed period of time.


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A microcontroller that operates in a wide operating range will help

to sustain long operation across battery discharges.


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One T!$e Progra$$a1e ?OTP@ )CU- -t is advantageous to

choose a microcontroller with OTN features to prevent reverse

engineering of the "rmware by competitors and hackers.

Hard(are Re1!a!1!t2

2teps to control and be immune to electromagnetic interference

should be implemented as in any embedded system where

sensitive electronics are next to a potential noise source such as a

motor. ;ardware that is not reliable may reset and result in a

vulnerable safe.

The less hardware components there are, the fewer components

that can fail and the greater the system reliability. 3ewer

components will also lower power consumption. 2ystem on Ghip

>2oG? microcontrollers can be used to integrate many hardware

functions to reduce component count, which in turn increases

reliability, decreases power consumption, and reduces cost.

A Nrogrammable 2ystem on Ghip >PSoC? can do power

measurement using internal comparators and Analog to :igital

Gonverters >A:G?. A buer can be controlled using Nulse !idth

5odulation >N!5? integrated on the 2oG.

Detect!ng Open Safe- 5any of the use scenarios reuire that

the "rmware detect whether the safe is open. An optical sensor
http://www.cypress.com/?id=1353http://www.cypress.com/?id=1353


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can be used to detect that the door is open. The optical sensor is

controlled by the microcontroller to determine this condition.

U#er procedure# and u!1t>!n #e1f>te#t ?BIST@-

A clear procedure for changing batteries is needed as the user

may have to change batteries during the lifetime of the safe and

may not have access to the safe manual. Built#in 2elf Test

capabilities can run through all the interfaces of the board to

ensure there is no fault after the replacement of the battery.

)anufactur!ng.

Jast but not the least is the challenge to program the electronic

safe with "rmware and later run manufacturing test to ensure that

all the blocks operate as expected and the unit is free of any

manufacturing defects.

To ensure that there is no fraud by the contract manufacturer, a

programming $ig with authentication may have to be

implemented. The manufacturing test procedure should ensure it

covers &CCV of the hardware.

%!$!tat!on# and (hat cou1d e !$pro"ed-

&a!1ure Ana12#!# on Returned )ater!a1-

-ncreasing the number of interfaces on the board is going to

increase the number of ways that an intruder can create havoc on


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CIRCUIT DIA9RA) &OR A )ICROCONTRO%%ER BASEDE%ECTRONIC SA&E

U1

LM555CN

9@:

&

:- 2'

O


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The keypad comprises of eleven >&&? bottoms

*&,F,H,I,M,(,',),K enter, =eset+ micro switches are used in

the keypad for soft press execution, total wires from the

keypad are &F in numbers *&,F,H,I,M,(,',),K %nter, =eset

and ground >earthing?, -c& >'I&I)? is an encoder which

encode every key that is been pressed in the keypad, ) lines

to H lines are A,B,G -GF >'I&C? is an decoder which decodes

every data from the ) to H line encoder into & bit, the output

from -GF is forward bias into LF, =M limit the excess current

from -GF, -GH is an astable multivibrator which oscillates at afreuency H(D;\ of transmission. =H =I and G& form the

freuency of oscillation whereby oscillating at H(D;\, pin is

the outputted oscillation, =& limits the amount of current

owing into L& at that instance the infra#red goes into

conduction thereby transmitting waves at higher freuency,

-GH is a carrier wave, the voltage from the keypad to -G& and

-GF are the modulating signal wave.

!hen the keypad at the actual code is been keyed the data

modulates through LF, -GH carrier the modulating signal

down to the infra#red receiver at a freuency of H(D;\,

when transmission is been done the infra#red receiver act as

a photo transistor thereby going into conduction acting as a

sink or an ampli"er, =' is a load resistance that act as a

load to the infra#red receiver from the PGG, -GI is a

processor which decode the input transmission data from the

infra#red transmitter crystal oscillator is connected to -cI pin


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&M and &( causing oscillation in the processor, at the

instance pin ) and && goes into conduction LH and LI are

forward bias, which also act as a sink or an ampli"er thereby

"ring the relay & and relay F at this point the motor turns

clockwise thereby opening the electronic safe, when the

keypad is pressed again the same process ow into the

transmitter and the receiver, -GF decodes the button from

the keypad LH and LI are forward bias "ring the relay into

conduction, the motor turns anti#clockwise the door of the

safe is closed. The opening and closing of the safe depends on the actual

key or code that is being press in the keypad which is being

decoded by -GI, that makes the motor to turn clockwise or

anti#clockwise. !hen the wrong code is pressed transmission

of data takes place, -GI decodes the wrong transmission

which is being transmitted from the transmitter, LH and LI

are reverse bias thereby the motor of the safe remains still

>there is no conduction?


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CHAPTER &I*E

CONC%USION AND RECO))ENDATION

-n conclusion we can be say that the microcontroller based

electronic safe ensures safety in a particular area where it is

applied. The main brain of this circuit which is the micro controller

reduces the number of component reuired to carryout complex

functions in the construction of this pro$ect. -f a right code is

keyed in, it will grant the access and the safe will automatically

open. But if wrong, it will deny the access and the safe will not

open.

RECO))ENDATION

-t is hereby recommended that this design be employed in

carrying out electronic safe pro$ects including banking safe,

temporarily store cash, industrial places, in a hotel rooms for safe


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keeping and auditorium o6ces. -t provides users with a secure,

convenient and cost e1ective way of locking safe. -t is further

suggested that the department should allocate pro$ects at the

beginning of the semester to enable the students source for fund

and other things that can help them carry out their pro$ects.

Electronic Safe2

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