exam hall automation

7/29/2019 Exam Hall Automation

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SYNOPSIS

The ongoing growth of technology has necessitated the use of more simpler and effective

systems as a replacement to the existing ones.

Our project is based on automating the access control and security operations involved in

an exam hall. Earlier, there was the conventional system using board and chart. Now, it can be

carried using non-contact devices, with the help of Radio Frequency Identification (RFID).

RFID cards are provided to students, these cards carry their own identification number in a

coded format, which can be retrieved by the reader only. By means of this the authentication of

the student can be verified. Then is the access control at various points inside the organization.

In order to avoid tress passing and in cases of theft of cards, we can add a keypad for entering a

password in the next level of project. Thereby it achieves a two level security.

Acting as a substitute for security personnel, this gives a better reliability and ease of use, both

for the students and colleges.

It finds quite an important application in Pay roll calculation, libraries; defense weapons

storage places (where only certain persons are authorized to enter), industrial monitoring and so

on. Our primary application that we have focused on is access control of students of different

exam halls inside the same building.


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CONTENTS

NAME OF THE C H APTER PAGE NO.

1. ABSTRACT

2. LIST OF TABLES

2.2 Features of the 125 kHz RFID reader

3. LIST OF FIGURES

3.1 Typical RFID System -

3.2 Basic Tag assembly -

3.3 Basic Tag IC architecture -

3.4 How Tags communicate -

3.5 Creation of tow higher frequency side bands -

3. 6 Typical pin details of the Chip inside the RFID card -

3.7 Block diagram of the Chip -

3.8 Modulation Signal and modulated signal -

3.9 Block diagram of 125kHz RFID reader -

3.10Output signal from reader -

3.11 Typical application -

3.12Block diagram of Access control -

3.13Block diagram of the system -

3.14 Circuit Diagram of the system

4. LIST OF SYMBOLS AND ABSRIVIATION


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5. INTRODUCTION

1.1 EXISITING TECHNOLOGIES & NEED FOR RFID -

1.2 RFID TECHNOLOGY -

1.3 WORKING OF RFID TAGS -1.4 WORKING OF THE RFID READER

6. RF BASED ACCESS CONTROL

2.1 BLOCK DIAGRAM -

2.2 WORKING

2.3 CIRCUIT DIAGRAM -

2.4 DESCRIPTION

7. MICROCONTROLLER-AT89S52

3.1 DISCRIPTION

8. APPLICATION & CONCLUSION

APPENDICES

REHERENCES -


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CHAPTER 1

INTRODUCTION

The concept of access control is brought about using a card, a corresponding card

reader and a control panel interfaced with the server. The card is a proximity card with a

unique identification number integrated in it. The reader reads the data and sends it to the

control panel, which is the micro controller. This controller checks the validity of the data with

the server, which bears the database. The server is loaded with the details about the employee

for that number, such as the name, designation, his access locations in the organization and

other necessary details.

The control panel checks whether he/she is allowed to enter the particular door or not.

Then he/she is requested for a password. The employee enters it using a keypad interfaced with

the controller. The controller again checks it with the server for authenticity. If the employee is

authentic, then he/she is allowed access in the particular entrance.

The employees can be permitted in a given entrance as per his/her designation. The

access control is employed at this point. When a person of a particular designation is not

supposed to be allowed in a given entrance, he/she is not even requested for a password.

In our project, the card reader is a proximity card reader. The controller used is PIC

AT8952. The server database was created using MS Access and the programming parts were

carried out with VB, whereas the controller was programmed with Hi-tech C.


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1.1 EXISTING TECHNOLOGIES & NEED FOR RFID

We have seen the security personnel checking the employees identification cards at the

entrances to avoid illegal entry. The employees sign a register at the entrance before getting

in. This is still being practiced in most of the companies.

However, the disadvantages are that, when there is a necessity of providing control at

many locations inside the company, a person at each point will not be an economical way of

implementing it.

Then came were the punch cards. Employees possess cards, which are punched when

they enter into the building. But it had disadvantages. Workers started to practice buddy

punching, for their co-workers.

Concerns about buddy punching-the practice where employees fraudulently clock their

co-workers in or out to give them credit for time that wasn't actually worked-led ContinentalAirlines to implement a fingerprint ID system to augment their automated employee time and

attendance recording system. The company expanded the system from Control Module after

it saved an estimated $100,000 in the first year. This led to the bar code readers.

It is a much common sight to see a bar code reader in the companies. These are used to

check with the employees identification. The employees swipe the card in the provided slot.

Then the access is given after checking the authenticity of the card. This was a substitute to

the security and emerged as a new technique in access control. This acted as a starting to the

automation of the access control. But, the bar code readers are contact readers where, the

cards are required to touch the readers.

With growth of technology and giant leap in the field of Radio frequency transmission, a

requirement for the same application using RF is desired.


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the card. This simplifies the usage for the employees. This technology is crawling into the

companies and has the potential to substitute the preceding technologies.

1.2 RFID TECHNOLOGY

RF technology is used in many different applications, such as television, radio,

cellular phones, radar, and automatic identification systems. The term RFID (radio frequency

identification) describes the use of radio frequency signals to provide automatic identification

of items.

Radio frequency (RF) refers to electromagnetic waves that have a wavelength suited

for use in radio communication. Radio waves are classified by their frequencies, which are

expressed in kilohertz, megahertz, or gigahertz. Radio frequencies range from very low

frequency (VLF), which has a range of 10 to 30 kHz, to extremely high frequency (EHF),

which has a range of 30 to 300 GHz.

RFID is a flexible technology that is convenient, easy to use, and well suited for

automatic operation. It combines advantages not available with other identification

technologies. RFID can be supplied as read-only or read / write, does not require contact or

line-of-sight to operate, can function under a variety of environmental conditions, and

provides a high level of data integrity. In addition, because the technology is difficult to

counterfeit, RFID provides a high level of security.

RFID is similar in concept to bar coding. Bar code systems use a reader and coded

labels that are attached to an item, whereas RFID uses a reader and special RFID devices that

are attached to an item. Bar code uses optical signals to transfer information from the label to

the reader; RFID uses RF signals to transfer information from the RFID device to the reader.

Radio waves transfer data between an item to which an RFID device is attached and

an RFID reader. The device can contain data about the item, such as what the item is, what

time the device traveled through a certain zone perhaps even a parameter such as


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RFID technology uses frequencies within the range of 50 kHz to 2.5 GHz. An RFID

system typically includes the following components:

An RFID device (transponder or tag) that contains data about an item

An antenna used to transmit the RF signals between the reader and the RFID device

An RF transceiver that generates the RF signals

A reader that receives RF transmissions from an RFID device and passes the data to a host

system for processing

In addition to this basic RFID equipment, an RFID system includes application-

specific software.

1.3 WORKING OF THE RFID TAGS

The RFID tags based on the mode of operation are classified as Active and Passive

tags. The classification is done on basis of the tags ability to transmit the code embedded in

it. Hence an active tag is capable of transmitting to a reader independently, whereas the

passive tag needs an external excitation for to transmit the code. The reader usually provides

the excitation. Further each of the tags either active or passive has their own frequency of

operation. We have used the passive type of tag operating at a frequency of 125 kHz in our

j t


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PACKAGING

Tags are manufactured in a wide variety of packaging formats designed for different

applications and environments. The basic assembly process consists of first a substrate

material (Paper, PVC, PET...); upon which an antenna made from one of many different

Conductive materials including Silver ink, Aluminum and copper is deposited. Next the Tag

chip itself is connected to the antenna; using techniques such as wire bonding or flip chip.

Finally a protective overlay made from materials such as PVC lamination, Epoxy Resin or

Adhesive Paper, is optionally added to allow the tag to support some of the physical

conditions found in many applications like abrasion, impact and corrosion.

Figure 1.2: BASIC TAG ASSEMBLY


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TAG ICS

Figure 1.3: BASIC TAG IC ARCHITECTURE

RFID tag ICs are designed and manufactured using some of the most advanced andsmallest geometry silicon processes available. The result is impressive, when you consider

that the size of a UHF tag chip is around 0.3 mm2

In terms of computational power, RFID tags are quite dumb, containing only basic

logic and state machines capable of decoding simple instructions. This does not mean that

they are simple to design! In fact very real challenges exist such as, achieving very low

power consumption, managing noisy RF signals and keeping within strict emission

regulations. Other important circuits allow the chip to transfer power from the reader signal

field, and convert it via a rectifier into a supply voltage. The chip clock is also normally


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The amount of data stored depends on the chip specification, and can range from just

simple Identifier numbers of around 96 bits to more information about the product with up to

32 Kbits. However, greater data capacity and storage (memory size) leads to larger chipsizes, and hence more expensive tags. In 1999 The AUTO-ID center (now EPC Global)

based at the MIT (Massachusetts Institute of Technology) in the US, together with a number

of leading companies, developed the idea of a unique electronic identifier code called the

EPC (Electronic Product Code). The EPC is similar in concept to the UPC (Universal

Product

Code) used in barcodes today. Having just a simple code of up to 256 bits would lead to

smaller chip size, and hence lower tag costs, which is recognized as the key factor for wide

spread adoption of RFID in the supply chain.

* See Appendix 1 for picture of the card employed in the project

TAG CLASSES

One of the main ways of categorizing RFID tags is by their capability to read and

write data.

This leads to the following 4 classes. EPC global has also defined five classes

CLASS 0 READ ONLY. Factory programmed

These are the simplest type of tags, where the data, which is usually a simple ID number,

(EPC) is written only once into the tag during manufacture. The memory is then disabled

from any further updates. Class 0 is also used to define a category of tags called EAS

(electronic article surveillance) or anti-theft devices, which have no ID, and only announce

their presence when passing through an antenna field.

CLASS 1 WRITE ONCE READ ONLY (WORM) Factory or User programmed


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further writes are allowed and the tag can only be read. Tags of this type usually act as simple

Identifiers

CLASS 2 READ WRITE

This is the most flexible type of tag, where users have access to read and write data

into the tags memory. They are typically used as data loggers, and therefore contain more

memory space than what is needed for just a simple ID number.

CLASS 3 READ WRITE with on board sensors

These tags contain on-board sensors for recording parameters like temperature, pressure, and

motion, which can be recorded by writing into the tags memory. As sensor readings must be

taken in the absence of a reader, the tags are either semi-passive or active.

CLASS 4 READ WRITE with integrated transmitters.

These are like miniature radio devices that can communicate with other tags and devices

without the presence of a reader. This means that they are completely active with their own

battery power source.

ACTIVE AND PASSIVE TAGS

Passive tags use the reader field as a source of energy for the chip and for

Communication from and to the reader. The available power from the reader field, not only

reduces very rapidly with distance, but is also controlled by strict regulations, resulting in a

limited communication distance of 4 - 5m when using the UHF frequency Band (860 MHz

930 MHz).

Semi-Passive (battery assisted backscatter) tags have built in batteries and therefore

do not require energy from the reader field to power the chip. This allows them to function

with much lower signal power levels, resulting in greater distances of up to 100 meters.


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Active tags are battery-powered devices that have an active transmitter onboard.

Unlike passive tags, active tags generate RF energy and apply it to the antenna. This

autonomy from the reader means that they can communicate at distances of over severalkilometers.

HOW TAGS COMMUNICATE

Near and Far fields

In order to receive energy and communicate with a reader, passive tags use one of the

two following methods. These are near field, which employs inductive coupling of the tag to

the magnetic field circulating around the reader antenna (like a transformer), and far field,

which use similar techniques to radar (backscatter reflection) by coupling with the electric

field. The near field is generally used by RFID systems operating in the LF and HF frequency

bands, and the far fields for longer read range UHF and microwave RFID systems.

Figure 1.4: How Tags communicate


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Tags at these frequencies use inductive coupling between two coils (reader antenna

and tag antenna) in order to supply energy to the tag and send information. The coils

themselves are actually tuned LC circuits, which when set to the right frequency (ex; 13.56

MHz), will maximize the energy transfer from reader to tag. The higher the frequency the

less turns required (13.56 MHz typically uses 3 to 5 turns). Communication from reader to

tag occurs by the reader modulating (changing) its field amplitude in accordance with the

digital information to be transmitted (base band signal). The result is the well-known

technique called Amplitude modulation (AM). The tags receiver circuit is able to detect the

modulated field, and decode the original information from it. However, whilst the reader has

the power to transmit and modulate its field, a passive tag does not. How communication is

therefore achieved back from tag to reader?

The answer lies in the inductive coupling. Just as in a transformer when the secondary

coil (tag antenna) changes the load and the result is seen in the Primary (reader antenna). The

tag chip accomplishes this same effect by changing its antenna impedance via an internal

circuit, which is modulated at the same frequency as the reader signal. In fact its a little more

complicated than this because, if the information is contained in the same frequency as the

reader, then it will be swamped by it, and not easily detected due to the weak coupling

between the reader and tag. To solve this problem, the real information is often instead

modulated in the side bands of a higher sub- carrier frequency, which is more easily detected

by the reader

Figure 1.5: Creation of two higher frequency side-bands


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If many tags are present then they will all reply at the same time, which at the reader

end is seen as a signal collision and an indication of multiple tags. The reader manages this

problem by using an anti-collision algorithm designed to allow tags to be sorted and

individually selected. There are many different types of algorithms (Binary Tree, Aloha....),

which are defined as part of the protocol standards. The number of tags that can be identified

depends on the frequency and protocol used, and can typically range from 50 tags/s for HF

and up to 200 tags/s for UHF.

Once a tag is selected, the reader is able to perform a number of operations such as

read the tags identifier number, or in the case of a read/write tag write information to it. After

finishing dialoging with the tag, the reader can then either remove it from the list, or put it on

standby until a later time. This process continues under control of the anti collision algorithm

until all tags have been selected.

THE 125 KHZ RFID CARD

The card used in our project is a passive Radio Frequency Identification (RFID)

device for low-frequency applications (100 kHz-400 kHz). The device is powered by

rectifying an incoming RF signal from the reader. The device requires an external LC

resonant circuit to receive the incoming RF signal and to send data. The device develops a

sufficient DC voltage for operation when its external coil voltage reaches approximately 10

Vpp.

This device has a total of 128 bits of user programmable memory and an additional 12

bits in its configuration register. The user can manually program the 128 bits of user memory

by using a contact less programmer. The device is a One-Time Programmable (OTP)

integrated circuit and operates as a read-only device after programming.

Figure 1.6: TYPICAL PIN DETAILS OF THE CHIP INSIDE THE RFID CARD

FEATURES Factory programming and memory serialization.


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96 or 128 bits of One-Time Programmable (OTP) user memory (also supports 48 and 64-bit

protocols)

Typical operation frequency: 100 kHz-400 kHz

Ultra low-power operation (5 A @ VCC = 2V)

Modulation options:

- ASK, FSK, PSK

Data encoding options:

- NRZ Direct, Differential Biphase, Manchester Biphase

Figure 1.7: BLOCK DIAGRAM OF THE CHIP

The configuration register includes options for communication protocol (ASK, FSK,

PSK), data encoding method, data rate, and data length. These options are specified by

customer and factory programmed during assembly. Because of its many choices of

configuration options, the device can be easily used as an alternative or second source for

most of the existing low frequency passive RFID devices available today.

The device has a modulation transistor between the two antenna connections (VA and

VB). The modulation transistor damps or undamps the coil voltage when it sends data. The

variation of coil voltage controlled by the modulation transistor results in a perturbation of

voltage in reader antenna coil. By monitoring the changes in reader coil voltage, the data

transmitted from the device can be reconstructed.


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igure

EMBEDDED ACCESS CONTROL AND SECURITY SYSTEM USING RFID

1.4WORKING OF THE RFID READERThe reader is the one of the key element in the system it is responsible for initiating

the operation of the system.

The reader is a complete transponder, which implements all the important functions

for the system. It consists of a plastic tube that accommodates the read only integral circuit

(IC) and the antenna realized by the LC circuit.

The identifying data are stored in the 128-bit PROM realized as an array of laser

programmable fuses. The data are sent bit serially as a code.

Figure 1.9: BLOCK DIAGRAM OF THE 125 KHZ RFID READER


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Figure 1.10: OUTPUT SIGNAL FROM READER

Table 1: FEATURES

TYPICAL APPLICATION CIRCUIT

The block diagram shown below describes a typical application circuit. The circuit is

similar to circuits employed it RFID systems, the card and the reader interaction shown. The

frequency of operation is selected by tuning the reader by means of the LC circuit.

Figure 1.11: Typical Application


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* See Appendix 2 for picture of the Reader employed in your project

CHAPTER 2

RFID BASED ACCESS CONTROL

Managing access to resources is assuming increasing importance for organizations

everywhere, from small entrepreneurial companies to large corporate enterprises and

government bodies of all sizes.

Administering access to resources means controlling both physical access and logical

access, either as independent efforts or through an integrated approach. The Physical access

control protects both tangible and intellectual assets from theft or compromise. Logical

access control enables enterprises and organizations to limit access to data, networks and

workstations to those authorized to have such access.


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2.1 OVERVIEW OF THE RFID BASED ACCESS CONTROL SYSTEM

The access control system is composed of three elements:

A card (an identity credential) that is presented to a door reader.

A door reader, which indicates whether the card is valid and entry, is authorized.

A d hi h i l k d h i h i d


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Behind the scenes is a complex network of computers and software that incorporates robust

security functionality.

ACCESS CONTROL SYSTEM COMPONENTS

The system is made up of the following components

ID credential

Door reader

Door lock

Control panel

Access control server

Software

Database

Figure 2.1: Block Diagram of Access control


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ACCESS CONTROL PROCESS

The access control process begins when the user presents the card to the reader, which

is usually mounted next to a door or entrance portal. The reader extracts data from the card,

processes it and sends it to the control panel.

The control panel first validates the reader and then accepts the data transmitted by

the reader. What happens next depends on whether the system is centralized or distributed.

In a centralized system, the control panel transmits the data to the access control

server. The access control server compares the data received from the card with the

information about the user that is stored in a database. Access control software determines

the users access privileges and authorization, the time, date and door entered, and any other

information that a company may require to ensure security. When access is authorized, the

access control sever sends a signal to the control panel to unlock the door. The control panel

then sends out a signal to the appropriate door lock, which unlocks the door.

In a distributed system, the control panel allows or denies entry. The access control

server periodical provides control panels with data that enable the control panel software to

determine whether the user is authorized for access. The control panel then performs the

access control server functions described above and makes the decision to allow or denyentry. Enabling control panels to perform the decision function has the advantage of

requiring less communication between the control panels and a central access control server.

The access control system components are described in detail

ID credential

A number of different id technologies are currently in use for access control:

magnetic stripe wiegand strips barium ferrite 125 kHz proximity card technology contact


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Some credential technologies are read only. Information is permanently recorded on

the credential and when the credential is presented to a reader the information is send to the

system. This type of credential only validates that the information is authentic. It does not

confirm that the person presenting the credential is the person authorized to possess it.

DOOR READER

The door reader can have one or more interfaces, accommodating some combination

of both the contact less card and the pin pad. How the reader responds depends on the type of

credential presented and the organization security policy.

When the reader is used with a contact less card, it acts as a small, allow power radiotransmitter and receiver, constantly transmitting an RF field called an excite field. When the

card is within the range of the excite field, the internal antenna on the card converts the field

energy into electricity that powers the chip on the card. The chip then uses the antenna to

transmit data to the reader.

When the reader has received all required data, it typically processes the information

in one of the two ways. Either the information is immediately sent to the control panel, or the

reader analyzes the data before sending it to the control panel. Both methods are widely

deployed.

The simplest readers send data directly to the control panel. These readers do nothing

to evaluate the data or determine the legitimacy of the credential. These readers are typically

one-factor readers and are generic, so that they can be stocked in inventory and easily added

to or swapped out of an access control system.

Readers that analyze data must be integrated into the access control system. That is,

they must interpret and manipulate the data sent by the card and then transmit the data in a

form that is usable by the control panel. Such a system can offer an increased level of

security. The reader can determine the legitimacy of the card, compare it with the PIN entry

and manipulate the credential data so that what the reader sends to the control; panel is not

the same as what was read from the card. The process of authenticating the card to the reader


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CONTROL PANEL

The control panel (often referred to as the controller or simply the panel) is the central

communication point for the access control system. It typically supplies power to the

interfaces with multiple readers at different access points. The controller connects to the

electro-mechanical door lock, a relay switch in our project. It can be connected to different

alarms (example Buzzer, sirens, lights). And finally the control panel is usually controlled

to an access control server.

Depending on the system design, the control panel may process data from the card

reader and the access control server and make the final authorization decision, or it may pass

the data to the access control server to make this decision. Typically, the control panel makes

the decision to turn ON the relay and pass the transaction data to the host computer and

unlocking signal to the reader. It is important for the control panel to generate the unlocking

signal, since the control panel is located inside the facility or in a secure room, while the card

reader is located in an insecure or open area.

Finally, the control panel stores data format information. This information identifies

what portion of the data stream received from a card is used to make access control decisions.

Cards and readers implemented with different technologies can exchange data in different

formats. However, the control panel needs to know how to interpret and process this data.

For example, if a reader sends 35 bits of data and the control panel is designed to read only

26 bits, the panel must either reject the data or truncate 9 bits. The data format control how

the panel interprets received data.

ACCESS CONTROL SERVER

The head end system (also referred to as back-end system or host system) includes

the access control server, software and a database. The database contains updated

information on users access rights.


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control panel. The software correlates the card data with the data in the database, determines

the persons access privileges, and indicates whether the person can be admitted.

Most systems are decentralized. In a decentralized system, the access control server

periodically sends updated access control information to the control panels and allows them

to operate independently, making the authorization decision for the credential presented

based on data stored in the panel.

The operational characteristics for centralized or decentralized systems are

determined from the specific implementing organizations access control requirements.

ACCESS CONTROL SYSTEM DATA FORMATS

The access control systems data format is a critical design element. Data format refers

to the bit pattern that the reader transmits to the control panel. The format specifies how

many bits make up the data stream and what these bits represent. For example, the first fewbits represent the facility code, the next few a unique credential ID number, the next few

parity and so on.

Each access control system has its own format, making every vendors code unique.

Like the pattern of teeth on a door key, the formats are kept secret to prevent an unauthorized

person or company from duplicating a card.

OPERATIONAL RANGE

One important characteristic of access control system operation is the distance from

the reader at which the credential is effective (called the operational range).

The operational range is determined by many factors, including both the systems


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Antenna shape

Number of antenna turns

Antenna material

Surrounding materials Credential orientation to the reader

Electrical parameters of the chip

Anti-collision features

Field strength of the reader

BLOCK DIAGRAM

Figure 2.2: Block Diagram of System


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WORKING

COMPONENTS SETUP

The system is constructed by means of the following major components.

125 KHZ RFID card

125 kHz Proximity card reader

At89S52 Micro controller

16 X 2 LCD module

Relay control

RS 232 interface cable

Server

USER SECTION

The users, say employees in an organization are provided with the 125 kHz RFID

cards. The user has to flash his card to the reader; the reader in turns detects the card and

checks for the authenticity. If the card is genuine, it prompts the user to enter his password.

The user can enter the password by means of the keypad provided near the reader. If the

password is accepted the door is unlocked and the user is provided access.

CONTROL PANEL (OR) CONTROLLER SECTION

This section is about the AT89S52 Micro controller. The coding as per the desired

operation is programmed onto the flash memory of the chip. Hence once the reader detects

the card, and when the user enters the password it reaches the controller. The controller in

turn forwards it to the PC by means of the RS 232 cable interface provided. If the details are

genuine, the PC sends Ok signal to the controller to unlock the door for the user to enter.


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PC SECTION (OR) SERVER

A server stores all the details pertaining to the users. The details are initially fed onto

the server database before the cards are issued. Hence each user is allocated a with a definite

access rights as per the requirements. Further when an user gains access after all the

authentication process, the details that pertain to the involved access operation such as date &

time of entry, door entered, etc; are all stored. Thus details of all those who gain entry are

stored. These details can be retrieved at a future point of time for any processing.

The database for the users is created using MS access and for the processingoperations Visual basic 6 is used in our Project.

CIRCUIT DIAGRAM DESCRIPTION

The circuit diagram consists of the following parts:

Power supply:

The power supply is of two ranges, +5V for the micro controller and +12 V for the

relay switch. This was constructed using 7805 and 7812 IC s respectively. They are provided

with a 9-0-9 V and a 15-0-15 V step-down transformer. After filter circuits, they are given to

the respective components.

LCD:

A 16 X 2 LCD module is used for the display. The LCD is connected to the micro

controller for displaying any text to the user. A potentiometer is used to vary the brightness

of the LCD display.


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Oscillator:

A crystal oscillator of 11.0592 MHz is connected with capacitor combination to

provide the clock frequency for the micro controller.

Relay:

The relay is used to open or close the door. In our project, it is used to switch on a

230 V powered AC electric lamp. The relays are driven using driver circuits. These relays

energize on a signal from the controller. The two electric lamps signify the opening and

closing of an electronic door.

Interfacing with the server:

The server, generally a computer, usually communicates with the controller

through RS 232 serial port cable. This is connected through an RS 232 connector and a MAX

232 IC for driving the signals. The connection is given to the COM port in the computer to

connect the controller with the computer. This is the cable through which the controller

accesses the database.

RFID Card Reader


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MICROCO NTROLLER (AT89S52)

4.4.1 CR I TER I A F OR CHOOSI N G A

MICROCONTROLLER

The basic criteria for choosing a microcontroller suitable for the application are:

1) The first and foremost criterion is that it must meet the task at hand efficiently and cost

effectively. In analyzing the needs of a microcontroller-based project, it is seen whether an

8- bit, 16-bit or 32-bit microcontroller can best handle the computing needs of the task

most effectively. Among the other considerations in this category are:

(a) Speed: The highest speed that the microcontrollersupports.

(b) P a c ka g in g : It may be a 40-pin DIP (dual inline package) or a QFP (quad

flatpackage), or some other packaging format. This is important in terms ofspace,assembling, and prototyping the endproduct.

(c) Power c o nsumptio n : This is especially critical for battery-powered

products. (d) The number of I/O pins and the timer on the chip.

(f) How easy it is to upgrade to higher performance or lower consumption

versions. (g) C o s t per uni t: This is important in terms of the final cost of the

product in which a microcontroller is used.

2) The second criterion in choosing a microcontroller is how easy it is to develop productsaround it. Key considerations include the availability of an assembler, debugger, compiler,


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needed quantities both now and in the future. Currently of the leading 8-bit

microcontrollers, the

8051 family has the largest number of diversified suppliers. By supplier is meant a

producerbesides the originator of the microcontroller. In the case of the 8051, this has

originatedby Intel several companies also currently producing the 8051.

Thus the microcontroller AT89S52, satisfying the criterion necessary for the proposed

application is chosen for the task.

4.4.2

DE SC RI P T I O N :

The 8051 family of microcontrollers is based on an architecture which is

highly optimized for embedded control systems. It is used in a wide variety of

applications from


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military equipment to automobiles to the keyboard. Second only to the Motorola 68HC11

in eight bit processors sales, the 8051 family of microcontrollers is available in a wide

array of variations from manufacturers such as Intel, Philips, and Siemens. These

manufacturers have added numerous features and peripherals to the 8051 such as I2C

interfaces, analog to digital converters, watchdog timers, and pulse width modulated

outputs. Variations of the 8051 with clock speeds up to 40MHz and voltage

requirements down to 1.5 volts are available. This wide range of parts based on one core

makes the 8051 family an excellent choice as thebase architecture for a company's entire

line of products since it can perform many functions and developers will only have to

learn this oneplatform.

The AT89S52 is a low-power, high-performance CMOS 8-bit microcontrollerwith

8K bytes of in-system programmable Flash memory. The device is manufactured using

Atmels high-density nonvolatile memory technology and is compatible with the industry-

standard 80C51 instruction set and pinout. The on-chip Flash allows the program

memory to be reprogrammed in-system or by a conventional nonvolatile 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 ahighly-flexible and cost- effective solution to many embedded control applications. In

addition, 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 system to continue

functioning. The Power-down mode saves the RAM con-tents but freezes the oscillator,

disabling all other chip functions until the next interrupt or hardware reset.

4.4.3

F EA T U R ES:

The basic architecture of AT89C51 consists of the following 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

256 x 8-bit Internal RAM

32 Programmable I/O Lines


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Three 16-bit Timer/Counters

Eight Interrupt Sources

Full Duplex UART Serial Channel

Low-power Idle and Power-down Modes

Interrupt Recovery from Power-down Mode

Watchdog Timer

Fast Programming Time

Flexible ISP Programming (Byte and Page Mode)

4.4.4 P IN CONFIGURAT ION

Fig. 4.16 Pin di ag ram ofAT89S52


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Fig. 4 .17 B lo ck diag ram of the mic ro co ntro ller


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4.4.6 P I N 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. Port 0 can also be configured to be the multiplexed

low-orderaddress/data bus during accesses to external program and data memory.

In this mode, P0 has internalpull-ups.

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.

As inputs, Port

1 pins that are externally being pulled low will source current (IIL) because of the

internal pull-ups. In addition, P1.0 and P1.1 can be configured to be the

timer/counter

2 external count input (P1.0/T2) and the timer/counter 2 trigger input (P1.1/T2EX),

respectively, as shown in the following table.

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.

As inputs, Port pins that are externally being pulled low will source current (IIL)

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 (MOVX @ DPTR). In this application,Port 2 uses strong internal pull- ups when emitting 1s. During accesses to external

data memory that uses 8-bit addresses (MOVX @ RI), 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. 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. Asinputs, Port 3 pins that are externally being pulled low will source current (IIL)


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Alt er nate funct io ns of Port 3:

T a ble 4 .2 Alt e rn a t e fun c ti o ns of Port 3

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

oscillator is running resets the device. This pin drives high for 98 oscillator

periods afterthe watchdog times out.

4.4.6.1 Po we r- On R eset ci rcuit

Fig. 4 .18 Po wer -on re set ci rcu it

In order for the RESET input to be effective, it must have a minimum duration of

two machine cycles.

ALE/PROG: Address Latch Enable (ALE) is an output pulse for latchingthe low byte of the address during accesses to external memory. This pin is also


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may be used for external timing or clocking purposes. Note, however, that one

ALE pulse is skipped during each access to external data memory. If desired,

ALE operation can be disabled by setting bit 0 of SFR location 8EH. With

the bit set, ALE is active only during a MOVX or MOVC instruction.

Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has no

effect if the microcontroller is in external execution mode.

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: External Access Enable. EA must be strapped to GND in order to enable

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 Flashprogramming.

XTAL1: Input to the inverting oscillator amplifier and input to the internalclockoperating circuit.

XTAL2: Output from the inverting oscillatoramplifier.

4.4.6.2 The A T89 S52 o sci lla tor clo ckc ir cuit

It uses a quartz crystal oscillator.

We can observe the frequency on the XTAL2pin.


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MONITOR AND CONTROL OF GREENHOUSE ENVIRONMENT

C2

30pF

C1

30pF

XTAL2

XTAL1

GN D

Fig 4 .19 T he AT89 S52 oscillator clockcircuit

The crystal frequency is the basic internal frequency of the microcontroller.

The internal counters must divide the basic clock rate to yield

standard communication bit per second (baud) rates.

An 11.0592 megahertz crystal, although seemingly an odd value, yields a

crystal frequency of 921.6 kilohertz, which can be divided evenly by the standard

communication baud rates of 19200, 9600, 4800, 2400, 1200, and 300 hertz.

4.4.7 SP EC IAL F U NC T I ON REGISTERS

The Special Function Registers (SFRs) contain memory locations that are used

forspecial tasks. Each SFR occupies internal RAM from 0x80 to 0xFF.They are 8-bits

wide.

The A (accumulator) register or accumulator is used for most ALU operationsand

Boolean Bit manipulations.

Register B is used for multiplication & division and can also be used for

generalpurpose storage.

PSW (Program Status Word) is a bit addressable register

PC or program counter is a special 16-bit register. It is not part of SFR.

Program instruction bytes are fetched from locations in memory that are

addressed by the PC.


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Stack Pointer (SP) register is eight bits wide. It is incremented before data

is stored during PUSH and CALL executions. While the stack may reside

anywhere in on-chip RAM, the Stack Pointer is initialized to 07H after areset. This causes the stack to begin at location 08H.

DPTR or data pointer is a special 16-bit register that is accessible as two 8-

bit registers: DPL and DPH, which are used to used to furnish memory

addresses forinternal and external code access and external data access.

Control Registers: Special Function Registers IP, IE, TMOD, TCON, SCON,

and PCON contain control and status bits for the

interrupt system, the Timer/Counters, and the serialport.

Timer Registers: Register pairs (TH0, TL0) and (TH1, TL1) are the 16-bit

Counter registers for Timer/Counters 0 and 1, respectively.

4.4.8 ME MO RY OR GANI ZATI ON

MCS-51 devices have a separate address space for Program and Data Memory. Upto

64K bytes each of external Program and Data Memory can beaddressed.

P r og r am M e m o r y : If the EA pin is connected to GND, all program fetches

are directed to external memory. On the AT89S52, if EA is connected to

VCC,program fetches to addresses 0000H through 1FFFH are directed to

internal memory and fetches to addresses 2000H through FFFFH are to external

memory.

D a ta M e mo ry: The AT89S52 implements 256 bytes of on-chip RAM. Theupper

128 bytes occupy a parallel address space to the Special Function Registers.

This means that the upper 128 bytes have the same addresses as the SFR space

but are physically separate from SFR space. When an instruction accesses an

internal location above address 7FH, the address mode used in the instruction

specifies whether the CPU accesses the upper 128 bytes of RAM or the SFR

space Instr ctions hich se direct addressing access the SFR space The


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bytes of RAM can be divided into threeegments:

1. R e g i st e r B a n k s 0 -3: locations 00H through 1FH (32 bytes). The device after

reset defaults to register bank 0. To use the other register banks, the user must

select them in software. Each register bank contains eight 1-byte registers R0-R7.

Reset initializes the stack point to location 07H, and is incremented once to start

from 08H, which is the first register of the second registerbank.

2. B it Address a b l e Ar e a : 16 bytes have been assigned for this segment 20H-

2FH. Each one of the 128 bits of this segment can be directly addressed (0-7FH).

Each ofthe 16 bytes in this segment can also be addressed as abyte.

3. Sc r a tch P a d Area: 30H-7FH are available to the user as data RAM.

However, ifthe data pointer has been initialized to this area, enough bytes should

be left aside toprevent SP data destruction.

Fig. 4 .20 I n ter n a l m e m o ry block


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4.4.9 WATCHDOG TIMER (One-time Enabled wit h Reset-out)

The WDT is intended as a recovery method in situations where the CPU may be

subjected to software upsets. The WDT consists of a 14-bit counter and the Watchdog

Timer

Reset (WDTRST) SFR. The WDT is defaulted to disable from exiting reset. To enablethe

WDT, a user must write 01EH and 0E1H in sequence to the WDTRST register (SFRlocation

0A6H). When the WDT is enabled, it will increment every machine cycle while the

oscillator is running. The WDT timeout period is dependent on the external clock

frequency. There is no way to disable the WDT except through reset (either hardware reset

or WDT overflow reset). When WDT over-flows, it will drive an output RESET HIGHpulse at the RSTpin.

4.4.10 TI M E RS A N D

COUNTERS

Many microcontroller applications require the counting of external events such as

the frequency of a pulse train, or the generation of precise internal time delays between

computeractions. Both of these tasks can be accomplished using software techniques,

but software loops for counting or timing keep the processor occupied so that, otherperhaps more important, functions are not done. Hence the better option is to use

interrupts & the two 16- bit count- up timers. The microcontroller can programmed for

either of the following:

1. Count internal - acting astimer

2. Count external - acting ascounter

All counter action is controlled by the TMOD (Timer Mode) and the TCON

(Timer/Counter Control) registers. TCON Timer control SFR contains timer 1& 2

overflow flags, external interrupt flags, timer control bits, falling edge/low level

selector bit etc. TMOD timer mode SFR comprises two four-bit registers (timer #1, timer

#0) used to specify the timer/counter mode and operation.

The timer may operate in any one of four modes that are determined by modesbits

M1 and M0 in the TMODregister:

TIMER MODE 0: Setting timer mode bits to 00b in the TMOD register results in using


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TIMER MOD E - 1 : Mode-1 is similar to mode-0 except TL is configured as a full

8-bit counter when the mode bits are set to 01b in TMOD.

TIMER M O DE- 2 : Setting the mode bits to 10b in TMOD configures the timer to use

only the TL counter as an 8-bit counter. TH is used to hold a value that is loaded into

TL every

time TL overflows from FFh to 00h. The timer flag is also set when TLoverflows.

TIMER MOD E - 3 : In mode-3, timer-1 simply hold its count, where as timer 0 registers

TL0 and TH0 are used as two separate 8-bit counters. TL0 uses the Timer-0 control

bits. TH0 counts machine cycles and takes over the use of TR1 and TF1 from Timer-1.

4.4.11

I N T E R RU P TS

A computer has only two ways to determine the conditions that exist in internal

and external circuits. One method uses software instructions that jump to subroutines

on the states of flags and port pins. The second method responds to hardwaresignals, called interrupts that force the program to call a subroutine.

The AT89S52 has a total of six interrupt vectors: two external interrupts (INT0 and

INT1), three timer interrupts (Timers 0, 1, and 2), and the serial port interrupt. Each of

these interrupt sources can be individually enabled or disabled by setting or clearing

a bit in Special Function Register IE. IE also contains a global disable bit, EA, which

disables all interrupts at once.

Each interrupt forces the processor to jump at the interrupt location in the

memory. The interrupted program must resume operation at the instruction where the

interrupt tookplace. Program resumption is done by storing the interrupted PC address on

to stack.

RETI instruction at the end of ISR will restore the PCaddress.

4.4.12 MICROCON TRO LL ER CONFIGURAT ION U SED IN THE SET-UP


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1) Sensor output display

2) Actuator status display

Port details:

Port 0: Interfaced with the LCD data lines. Port 1: Interfaced with the ADC data lines

Port 2: Interfaced with the LCD Control lines and AC Interface control

Port 3: Interfaced with the ADC control lines

LIQU I D CRY S TAL DISPLAY

A liquid crystal display (LCD) is a thin, flat display device made up of any number

ofcolor or monochrome pixels arrayed in front of a light source or reflector. Each pixel

consists of a column of liquid crystal molecules suspended between two transparent

electrodes, and two polarizing filters, the axes of polarity of which are perpendicular to

each other. Without the liquid crystals between them, light passing through one would

be blocked by the other. The liquid crystal twists the polarization of light entering one

filter to allow it to pass through the other.

Many microcontroller devices use 'smart LCD' displays to output visual

information. LCD displays designed around Hitachi's LCD HD44780 module, are

inexpensive, easy to use, and it is even possible to produce a readout using the 8x80

pixels of the display. They have a standard ASCII set of characters and mathematical

symbols.

For an 8-bit data bus, the display requires a +5V supply plus 11 I/O lines. For a 4-

bit data bus it only requires the supply lines plus seven extra lines. When the LCD display

is not enabled, data lines are tri-state and they do not interfere with the operation of the

microcontroller.

Data can be placed at any location on the LCD. For 162 LCD, the addresslocations

are:

First line 80 81 82 83 84 85 86 through 8F

Second line C0 C1 C2 C3 C4 C5 C6 through CF

Fig 4 .22 A ddr ess lo cations for a 2 x16 li ne LCD

4.5.1 SIGNALS TO THE LCD

The LCD also requires 3 control lines from the microcontroller:


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line is low, the LCD is disabled and ignores signals from R/W and RS. When (E)

line is high, the LCD checks the state of the two control lines and responds

accordingly.

2) Read/Write (R/W)

This line determines the direction of data between the LCD andmicrocontroller.

4.7 R E L A YS

A relay is an electrical switch that opens and closes under the control of another

electrical circuit. In the original form, the switch is operated by an electromagnet to open

orclose one or many sets of contacts. It was invented by Joseph Henry in 1835. Because

a relay is able to control an output circuit of higher power than the input circuit, it can be

considered

to be, in a broad sense, a form of an electrical amplifier.


44/63

Fig . 4.26 Suga r cube relay

Despite the speed of technological developments, some products prove so

popular that their key parameters and design features remain virtually unchanged for

years. One suchproduct is the sugar cube relay, shown in the figure above, which

has proved useful to many designers who needed to switch up to 10A, whilst using

relatively little PCB area

Since relays are switches, the terminology applied to switches is also applied

to relays. A relay will switch one or more poles, each of whose contacts can be thrown by

energizing the coil in one of three ways:

1.N o rmally - open (N O) contacts connect the circuit when the relay is activate d; the

circuit is disconnected when the relay is inactive. It is also called a FORM A contact or

make contact.

2.N o rmally - c lo s ed (N C) contacts disconnect the circuit when the relay is activated ; the

circuit is connected when relay is inactive. It is also called FORM B contact or

break contact

3.Cha n g e - o ver or dou b l e -th r ow contacts control two circuits ; one normally open

contact and one normally closed contact with a common terminal. It is also called a

Form C transfercontact.

The following types of relays are commonly encountered:


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"C" denotes the common terminal in SPDT and DPDT

types

Fi g . 4 .27 Di f ferent ty p e s of

R e la y s

SPST - Sin g le Pole Sin g le Thr o w : These have two terminals which can be

connected or disconnected. Including two for the coil, such a relay has four

terminals in total. It is ambiguous whether the pole is normally open or normally

closed. The terminology "SPNO" and "SPNC" is sometimes used to resolve the

ambiguity.

SPDT - Sin g le Pole Dou b le Thr o w : A common terminal connects to either of

two others. Including two for the coil, such a relay has five terminals in total.

DPST - Dou b le Pole Sin g le Thr o w : These have two pairs of terminals. Equivalent

to two SPST switches or relays actuated by a single coil. Including two for the coil,

such a relay has six terminals in total. It is ambiguous whether the poles are

normally open, normally closed, or one ofeach.

DPDT - Dou b le Pole Dou b le Throw: These have two rows of change-overterminals.

Equivalent to two SPDT switches or relays actuated by a single coil. Such a relay

has eight terminals, including the coil.

QPDT - Quadr up le Po l e Do uble Th r ow : Often referred to as Quad Pole Double

Throw, or 4PDT. These have four rows of change-over terminals. Equivalent to

fourSPDT switches or relays actuated by a single coil, or two DPDT relays. In

total, fourteen terminals including the coil.


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When it is low, data is written to the LCD. When it is high, data is read fromthe

LCD.

3) R e gi ster s e le ct (RS)

With the help of this line, the LCD interprets the type of data on data lines. When it

is low, an instruction is being written to the LCD. When it is high, a character is being

written to the LCD.

4.5.1.1 Logic s t atus on c o n t r o l lines:

E - 0 Access to LCD disabled

- 1 Access to LCD enabled

R/W - 0 Writing data to LCD

- 1 Reading data fromLCD

RS - 0 Instruction

- 1 Character

4.5.1.2 W r i t i n g a n d r e ad ing the d a t a f r om the LCD:

Writing data to the LCD is done in several steps:

1) Set R/W bit to low

2) Set RS bit to logic 0 or 1 (instruction orcharacter)

3) Set data to data lines (if it is writing)

4) Set E line to high

5) Set E line to low

Read data from data lines (if it is reading):

1) Set R/W bit to high

2) Set RS bit to logic 0 or 1 (instruction orcharacter)

3) Set data to data lines (if it is writing)

4) Set E line to high

5) Set E line to low

4.5.2 P I N DESCRIPTION

Most LCDs with 1 controller has 14 Pins and LCDs with 2 controller has 16 Pins

(two pins are extra in both for back-light LED connections).


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Fig 4 .23 Pin d i a g ram o f 2 x 16 li ne LCD

Table 4 .23 P in descrip tion o f t he LCD

4.6 A LARM C IR CUITRY

BUZ Z ER:

A buzzer or beeper is a signaling device, usually electronic, typically used

in automobiles, household appliances such as a microwave oven.

Fig . 4.24 Elec trical symbol of a bu zzer


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It is connected to the control unit through the transistor that acts as an

electronic switch for it. When the switch forms a closed path to the buzzer, it sounds a

warning in the form of a continuous or intermittent buzzing or beeping sound.

The transistor acts as a normal controlled by the base connection. It switches

ON when a positive voltage from the control unit is applied to the base. If the positive

voltage is less than 0.6V, the transistor switches OFF. No current flows through the buzzer

in this case and it will not buzz. As can be seen in the buzzer circuitry given below, a

protection resistor of 10k ohm is used in order to protect the transistor from being

damaged in case ofexcessive current flow. In our system, the buzzer is designed to give a

small beep whenever one of the devices such as a cooler or a bulb turns on in order to

alert the user.

Fi g. 4 .25 Buzzer circuitry

4.7 R E L A YS

A relay is an electrical switch that opens and closes under the control of another

electrical circuit. In the original form, the switch is operated by an electromagnet to open

orclose one or many sets of contacts. It was invented by Joseph Henry in 1835. Because

a relay is able to control an output circuit of higher power than the input circuit, it can be

considered

to be, in a broad sense, a form of an electrical amplifier.


49/63

Fig . 4.26 Suga r cube relay

Despite the speed of technological developments, some products prove so

popular that their key parameters and design features remain virtually unchanged for

years. One suchproduct is the sugar cube relay, shown in the figure above, which

has proved useful to many designers who needed to switch up to 10A, whilst using

relatively little PCB area

Since relays are switches, the terminology applied to switches is also applied

to relays. A relay will switch one or more poles, each of whose contacts can be thrown by

energizing the coil in one of three ways:

1.N o rmally - open (N O) contacts connect the circuit when the relay is activate d; the

circuit is disconnected when the relay is inactive. It is also called a FORM A contact or

make contact.

2.N o rmally - c lo s ed (N C) contacts disconnect the circuit when the relay is activated ; the

circuit is connected when relay is inactive. It is also called FORM B contact or

break contact

3.Cha n g e - o ver or dou b l e -th r ow contacts control two circuits ; one normally open

contact and one normally closed contact with a common terminal. It is also called a

Form C transfercontact.

The following types of relays are commonly encountered:


50/63

"C" denotes the common terminal in SPDT and DPDTtypes

Fi g . 4 .27 Di f ferent typ e s of

R e la y s

SPST - Sin g le Pole Sin g le Thr o w : These have two terminals which can be

connected or disconnected. Including two for the coil, such a relay has four

terminals in total. It is ambiguous whether the pole is normally open or normally

closed. The terminology "SPNO" and "SPNC" is sometimes used to resolve the

ambiguity. SPDT - Sin g le Pole Dou b le Thr o w : A common terminal connects to either of

two others. Including two for the coil, such a relay has five terminals in total.

DPST - Dou b le Pole Sin g le Thr o w : These have two pairs of terminals. Equivalent

to two SPST switches or relays actuated by a single coil. Including two for the coil,

such a relay has six terminals in total. It is ambiguous whether the poles are

normally open, normally closed, or one ofeach.

DPDT - Dou b le Pole Dou b le Throw: These have two rows of change-overterminals.

Equivalent to two SPDT switches or relays actuated by a single coil. Such a relay

has eight terminals, including the coil.

QPDT - Quadr up le Po l e Do uble Th r ow : Often referred to as Quad Pole Double

Throw, or 4PDT. These have four rows of change-over terminals. Equivalent to

fourSPDT switches or relays actuated by a single coil, or two DPDT relays. In

total, fourteen terminals including the coil.

The Relay interfacing circuitry used in the application is:


51/63

1N4148

Fig. 4 .28 R el ay ci rcuitry

4.8 PO W ER S UP P LY CONNECTION

The power supply section consists of step down transformers of 230V primary to

9V and 12V secondary voltages for the +5V and +12V power supplies respectively. The

stepped down voltage is then rectified by 4 1N4007 diodes. The high value of capacitor

1000 F charges at a slow rate as the time constant is low, and once the capacitor charges

there is no resistor for capacitor to discharge. This gives a constant value of DC. IC 7805

is used forregulated supply of +5 volts and IC 7812 is used to provide a regulated supply

of +12 volts in order to prevent the circuit ahead from any fluctuations. The filter

capacitors connected after this IC filters the high frequency spikes. These capacitors

are connected in parallel with supply and common so that spikes filter to the common.

These give stability to thepowersupply circuit.

As can be seen from the above circuit diagrams, the rectified voltage from

the 4 diodes is given to pin 1 of the respective regulators. Pin 2 of the regulators is

connected to ground and pin 3 to Vcc. With adequate heat sinking the regulator can

deliver 1A output current. If internal power dissipation becomes too high for the heat

sinking provided, the thermal shutdown circuit takes over preventing the IC from

overheating.


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1Vin 7805 Vout

GND2

230V,50Hz

1000

uf 10

uf1uf


53/63

Fi g . 4.29 +5V Power supply circuit

Fig . 4 .30 +12V Power supply Circuit

APPLICATIONS

The RF Identification is finding its application in many fields and some of them are

described briefly below:

Access Control and Security

The cards can also be used for many of the work carried out inside the company such as:

Pay-roll calculation:

The employees in time and out time can be noted and their attendance can be

maintained. This in turn helps in calculating the salary that they have to get for the last month.

Human checking:

When somebody has to be traced inside a building, it can be done with the information

about the location he/she had recently checked-in inside the building. Also, in case of closing thegate for the day, accidental or deliberate presence of a person can be found by noting the


54/63

IMPLEMENTED APPLICATION OF THE PROJECT

Selective Access control

This is the application that our project is mainly focused on. In this, the students are

given access only into certain places inside the building and are restricted from entering into

certain other places demanding security. In any examhall, there are some restricted locations,

where permission is given only to employees of certain cadre or skill level. The others are

incompetent either on the ground of their cadre or their knowledge about the components and

equipments or objects, present in the location. RF ID provides a good solution to thisapplication.

"Proximity cards are one of the highest forms of ID, and are considered very secure. But

they can still be used for buddy punching," says Jimmy Bianco, Vice President of sales and

marketing for Control Module Inc.

So, apart from the card, a keypad is provided for entering the password, which is checked

for authenticity. So, this second level of security provides a complementary solution to the

access control inside the building.

The application provides an excellent example of how the technology can provide a

secure foundation upon which additional applications can be built.

OTHER APPLICATIONS

Vehicle Identification

Commercial trucks are fitted with RFID systems to monitor access and egress from

terminal facilities by fixing the RF ID tags in the vehicles.

This can also be used for ships entering the harbor This helps in maintaining record of


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Industrial Monitoring

In the plant environment, RF systems are ideally suited for the identification of high-

unit-value products moving through a tough assembly process (e.g., automobile or agricultural

equipment production where the product is cleaned, bathed, painted and baked). RF systems also

offer the durability essential for permanent identification of captive product carriers such as:

Tote boxes, containers, barrels, tubs, pallets, tool carriers, and free conveyor trolleys, lift

trucks, towline carts, and automatic guided vehicles.

This avoids the necessity of human beings having a watch over the products entering

various places, especially those having risk.

Animal Identification

Valuable breeding stock, laboratory animals involved in lengthy and expensive research

projects, meat and dairy animals, wildlife, and even prized companion animals present unique

identification problems that can be solved by innovative applications of RFID technology. They

can be monitored for their position in the breeding place, zoo, and other places.

CONCLUSION

The implementation of RFID based system in access control and security operations are

bound to increase in the future. The advantages, efficiency and reliability of the system have

made it manifest itself over the existing systems. The system achieves a two level security

making the incorporating firm more secure.

Further this system is compatible for the future upgradations like a Finger print scanner,

retina scanner, monitoring camera, etc. making it more versatile. With the introduction of more

smart RFID devices in the near future the system is going to rule the field of access control and

security.


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CHAPTER 4

APPENDICES

APPENDIX 1

EXAMPLES OF DIFFERENT FORMAT OF TAGS

Credit card size flexible labels with adhesive backs

Tokens and coins

Embedded tags injection molded into plastic products such as cases

Wrist band tags

Hard tags with epoxy case

Key fobs

Tags designed specially for Palettes and cases

Paper tags

VIEW OF THE 125 kHz CARD EMPLOYED IN OUR PROJECT


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MTP-125K4 Series Low Cost Proximity ReaderSize26.5 x 16.5 x 6.9 mm

Power5V@44mA nominal

Frequence125KHz

Read CardEM4001/4102

CodingManchester 64bitmodulus 64

I/O output 25mA sink/source

Annte 150Volt PKPK

Read Rangemax. 25cm

Read time100ms

Output FormatWeigen26/RS232 TTL ASCII

Pin Def. Photo

26.5mm

6.9mm

2.54 mm Pin 1---9

ASCIIRS232:

RS232/TTL (ASCII) Output

Pin3 Strap to +5

Pin1 Antenna 1 To External Antenna

Pin2 Antenna 2 To External Antenna (L:680uH)

16.5mm

1 2 3 4 5 6 7 8 9

K4


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Pin4 BEEP/LED 2.7KHz Logic

Pin5 DATA1(TTL) Serial Output (ASCII)

Pin6 DATAO(TTL) Serial Output inverted (ASCII inverted)

Pin7 /Reset Low Active

Pin8 Ground 0V

Pin9 VCC +4.6 through +5.5V

Output Format-Serial Output

02 10ASCII Data Characters Checksum 03

The checksum is the result of the exclusive or of the 5 Binary Data

bytes(the 10 ASCII data characters)

RS232 Output(Pin3 to High)

(a) 9600 bpsN81(b) PIN5TX Output(c) For exampleCard ID Number 62E3086CEDSend HEX as:

10ASCII DATA36H,32H 45H,33H 30H,38H 36H,43H 45H,44H

(6 2 H E 3 H 0 8 H 6 C H E D H)

CHECKSUM(62H) XOR (E3H) XOR (08H) XOR (6CH) XOR (EDH)=08H

So MTP-K4 Output AS02 36 32 45 33 30 38 36 43 45 44 08 03

(d) Every Byte output as:


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104us 104us 208us

PIN6

Start Bit Bit0 Bit1 Bit7 StopBit

104us 104us 208us


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Wiegand 26:

Weigen26 Output AS

Wiegand Output (Pin3 To Low)

Pin1 Antenna 1 To External Antenna

Pin2 Antenna 2 To External Antenna (L:680uH)

Pin3 Strap to +0V

Pin4 BEEP/LED 2.7KHz Logic

Pin5 One Output

Pin6 Zero Output

Pin7 /Reset Low Active

Pin8 Ground 0V

Pin9 VCC +4.6 through +5.5V

Pin3 Strap to +0V

Data Structure Wiegand 26 Bit

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

P(1) E E E E E E E E E E E E O O O O O O O O O O O O P(2)

EVEN Parity(E) ODD Parity(O)

P(1)=Parity Start Bit

P(2)=Parity Stop Bit

Wiegand(Pin3Low)(a) Output Result is the last 3 bytes of the IDNumber(62E3086CED)08H6CHEDHWiegand26,16Bit, Bit0 =1: D0=1,D1=0

Bit23=0: D0=0,D1=1


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b)

50us 1ms

DATA1

DATA0

P(1) Bit23 Bit22 Bit1Bit0 P(2)

1 0 0

1 1

MSB LSB

Motorola 26 bit wiegand format (50us/1ms)

K4 Annte


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exam hall automation

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