staff attendance using rfid module

7/30/2019 Staff Attendance using RFID module

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Anurag Engineering College

Department of ECE 1

1. INTRODUCTION

In the present scenario the two major problems faced by organizations are time

consuming manual attendance and wastage of electrical power. Our project is going to solve

these problems by using RFID technology.

The aim of this project is to take the attendance of staff members in a college very

easily by using their ID cards. We are going to give RFID cards for each and every staff

member. Whenever person with RFID card has reached the RFID reader then details of staff

members will be displayed on a LCD and will be recorded. Radio Frequency Identification

(RFID) is an automatic identification method, relying on storing and remotely retrieving data

using devices called RFID tags or transponders. So the RFID is a wireless identification.Normally the RFID system comprises of two main parts: RFID Reader and RFID Tag.

RFID Reader is an integrated or passive network which is used to interrogate

information from RFID tag (RFID tags contain antennas to enable them to receive and

respond to radio-frequency queries from an RFID transceiver). The RFID Reader may consist

of antenna, filters, modulator, demodulator, coupler and a micro processor.

RFID tags are categorized as either active or passive. Active RFID tags are

powered by an internal battery and are typically read/write, i.e., tag data can be rewritten

and/or modified. An active tag's memory size varies according to application requirements;

some systems operate with up to 1MB of memory. Passive RFID tags operate without a

separate external power source and obtain operating power generated from the reader. This

project uses passive tags. Read-only tags are typically passive and are programmed with a

unique set of data (usually 32 to 128 bits) that cannot be modified.

The significant advantage of all types of RFID systems is the non contact, non-

line-of-sight nature of the technology. Tags can be read through a variety of substances such

as snow, fog, ice, paint, crusted grime. The RF transmitter present in the RFID tag

continuously transmits the ID number containing in the tag. This ID number will be written

by the user initially. The RFID reader will be present with the user. Whenever the user wishes

to know the details of particular product, he has to bring the product near the RFID reader.

The signal strength at the receiver end increases when the object, along with the tag, is

brought near the read.Thus the reader reads the tag information and passes the data to the

controlling unit. The microcontroller displays the information related to that object on the

LCD.


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Department of ECE 2

1.1 Objective of the project

The project aims to make thing easy in colleges and companies etc using RFID

technology. The project uses the RFID technology and Embedded Systems to design this

application. The main objective of this project is to design a system which fixes a tag for

every object and when the user wants to know the details of the object, he has to bring this

object near the RFID reader, so that the reader reads the tag information and displays the

entire information of the object on the LCD.

This project is a device that collects data from the tag and codes the data into a

format that can be understood by the controlling section. This system also collects

information from the master device and implements commands that are directed by the

master.

The objective of the project is to develop a microcontroller based display system. It

consists of a RFID reader, microcontroller, the interfacing unit to allow the communication

between the microcontroller and RFID module, switch and the LCD.

1.2Back ground of the projectThe software application and the hardware implementation help the microcontroller

read the data from the RFID tag fixed to the object and display the details of the object on the

LCD. The system is totally designed using RFID and embedded systems technology.

The Controlling unit has an application program to allow the microcontroller interface

with the RFID reader, allows the RFID reader to read the data from the tag, pass the data to

the microcontroller and the controller displays the information of the object, by taking the

details of the object from the EEPROM, on the LCD. EEPROM is used to store the details of

the object with an unique code. Thus, the user can find the objects in a more easy way and the

details associated to it. The performance of the design is maintained by controlling unit.

1.3 Introduction to RFID technology

In recent years, radio frequency identification technology has moved from obscurity

into mainstream applications that help speed the handling of manufactured goods and

materials. RFID enables identification from a distance and unlike earlier bar-code

technology; it does so without requiring a line of sight. RFID tags support a larger set of


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Department of ECE 3

unique IDs than bar codes and can incorporate additional data such as manufacturer, product

type and even measure environmental factors such as temperature. Furthermore, RFID

systems can discern many different tags located in the same general area without human

assistance.

Fig.1.1: Three different RFID tags they come in all shapes and sizes.

Definition of RFID technology:

Radio frequency identification (RFID) is a general term that is used to describe a

system that transmits the identity (in the form of a unique serial number) of an object

wirelessly using radio waves. RFID technologies are grouped under the more generic

Automatic Identification (Auto ID) technologies.

RFIDTags:

Tags also sometimes are called transponders. RFID tags can come in many forms

and sizes. Some can be as small as a grain of rice. Data is stored in the IC and transmitted

through the antenna to a reader. The two commonly used RFID Transponders [2] are Active

(that do contain an internal battery power source that powers the tags chip) and Passive (that

do not have an internal power source, but are externally powered typical from the reader)

RFID Transponders.


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Department of ECE 4

RFID Reader:

A reader (now more typically referred to as an RFID interrogator) is basically a radio

frequency (RF) transmitter and receiver, controlled by a microprocessor or digital signal

processor. The reader, using an attached antenna, captures data from tags, then passes the

data to a computer for processing. The reader decodes the data encoded in the tag(s)

integrated circuit (silicon chip) and the data is passed to the host computer for processing.

Working of RFID:

Information is sent to and read from RFID tags by a reader using radio waves. Inpassive systems, which are the most common, an RFID reader transmits an energy field that

wakes up the tag and provides the power for the tag to respond to the reader. Data collected

from tags is then passed through communication interfaces (cable or wireless) to host

computer systems in the same manner that data scanned from bar code labels is captured and

passed to computer systems for interpretation, storage, and action.


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Department of ECE 5

2. LITERATURE SURVEY

During the research, we have encountered various type of automatic attendance system

depending on different technologies like barcode and biometric. Details of such systems are

follows:

2.1 Existing Systems

Attendance Recording System manufactured by Fortuna Impex Pvt. Ltd.

This system is using Bar Code technology for attendance recording. It combines a

proximity bar code reader, touch pad for inputting a PIN, and fingerprint reader, to give

businesses a fool proof method for preventing unauthorized personnel from entering

restricted areas. This system is using serial signals generated by bar code, PIN, and

fingerprint readings that are easily transmitted to one centrally located computer, which can

be used to control the entire system. The problem arises if a large number of card readers are

combined to form a more complex entry system. One option is to design a system that uses

several PCs, with one PC located near each device. However, the cost of purchasing so many

PCs can be prohibitive.

Employee Attendance System manufactured by Selvam Systems Pvt. Ltd.

This system is using RFID for attendance monitoring. This System assigns a unique

card number for each employee. An employee places the RFID card within 5cm distance

from the RFID Reader. The RFID Reader writes down the time, date and type of

departure/arrival. The type of arrival/departure is indicated on the LCD display. The display

also indicates the current time. The Interface software which is available with this system is

responsible for attendance record processing and it produces attendance reports in the

customer preferred format. Attendance processing (Interface) software can also be integrated

with the payroll software for salary calculation and employee tracking. Manual entry is also

possible.


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Department of ECE 6

2.2 Difference between barcode & RFID reader

Barcode Reader RFID Reader

Counterfeiting is easy. Counterfeiting is difficult.Scanner needs to see the barcode to read it. Scanner not required. No need to bring the

tag near the reader.

Can read only one tag at a time. Can read multiple tags at a time. Relatively

expensive compared to barcode.

Cannot be reused. Can be reused within the premises.

The barcode labels that triggered a revolution in identification systems long time ago

are inadequate in an increasing number of cases. They are cheap but the stumbling block is

their low storage capacity and the fact that they cannot be reprogrammed.

A feasible solution was putting the data on silicon chips. The ideal situation is

contactless transfer of data between the data carrying device and its reader. The power

required to operate the electronic data carrying device would also be transferred from the

reader using contactless technology. These procedures give RFID its name.

In a not so distant future, RFID enabled stores will monitor the consumption in real

time. Shelf will signal the inventory when it needs more stuff and inventory will pull supplies

from the manufacturer based on its level of stock.


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Department of ECE 7

3. PROPOSED MODEL

It discusses the design and working of the design with the help of block diagram and

circuit diagram and explanation of circuit diagram in detail. It explains the features, timer

programming, serial communication, interrupts of AT89S52 microcontroller. It also explains

the various modules used in this project.

Hardware implementation deals in drawing the schematic on the plane paper

according to the application, testing the schematic design over the breadboard using the

various ICs to find if the design meets the objective, carrying out the PCB layout of the

schematic tested on breadboard, finally preparing the board and testing the designed

hardware.

3.1 Block diagram of the project &description

The block diagram of the design is as shown in Fig 3.1. It consists of power supply

unit, microcontroller, RFID module, Serial communication unit, switch, EEPROM and LCD.

The brief description of each unit is explained as follows.

Fig 3.1: Block diagram for Inventory management system using RFID


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Department of ECE 8

Schematic diagram of the project:

Fig 3.2: Schematic diagram


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Department of ECE 9

3.2 Power supply

The input to the circuit is applied from the regulated power supply. The a.c. input

i.e., 230V from the mains supply is step down by the transformer to 12V and is fed to a

rectifier. The output obtained from the rectifier is a pulsating d.c voltage. So in order to get a

pure d.c voltage, the output voltage from the rectifier is fed to a filter to remove any a.c

components present even after rectification. Now, this voltage is given to a voltage regulator

to obtain a pure constant dc voltage.

Fig 3.3: Components of regulated power supply

Transformer:

Usually, DC voltages are required to operate various electronic equipment and these

voltages are 5V, 9V or 12V. But these voltages cannot be obtained directly. Thus the a.c

input available at the mains supply i.e., 230V is to be brought down to the required voltage

level. This is done by a transformer. Thus, a step down transformer is employed to decrease

the voltage to a required level.

Rectifier:

The output from the transformer is fed to the rectifier. It converts A.C. into pulsating

D.C. The rectifier may be a half wave or a full wave rectifier. In this project, a bridge rectifier

is used because of its merits like good stability and full wave rectification.


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Department of ECE 10

Filter:

Capacitive filter is used in this project. It removes the ripples from the output of

rectifier and smoothens the D.C. Output received from this filter is constant until the mains

voltage and load is maintained constant. However, if either of the two is varied, D.C. voltage

received at this point changes. Therefore a regulator is applied at the output stage.

Voltage regulator:

As the name itself implies, it regulates the input applied to it. A voltage regulator is

an electrical regulator designed to automatically maintain a constant voltage level. In this

project, power supply of 5V and 12V are required. In order to obtain these voltage levels,

7805 and 7812 voltage regulators are to be used. The first number 78 represents positive

supply and the numbers 05, 12 represent the required output voltage levels.

3.3 RFID Technology

RFID principles

Many types of RFID exist, but at the highest level, we can divide RFID devices

into two classes:

Activeand passive.

Fig 3.4: Active and Passive tags

Active tags require a power source i.e., they are either connected to a powered

infrastructure or use energy stored in an integrated battery. In the latter case, a tags lifetime

is limited by the stored energy, balanced against the number of read operations the device

must undergo. However, batteries make the cost, size, and lifetime of active tags impractical

for the retail trade.
http://2.bp.blogspot.com/_1YUZv5rd5AE/SIG4zGjyhRI/AAAAAAAABck/n8mckBAJe68/s1600-h/RFID-tags.bmp


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Passive RFID is of interest because the tags dont require batteries or maintenance.

The tags also have an indefinite operational life and are small enough to fit into a practical

adhesive label. A passive tag consists of three parts: an antenna, a semiconductor chip

attached to the antenna and some form of encapsulation. The tag reader is responsible for

powering and communicating with a tag. The tag antenna captures energy and transfers the

tags ID (the tags chip coordinates this process). The encapsulation maintains the tags

integrity and protects the antenna and chip from environmental conditions or reagents.

RFID Technology and Architecture:

Before RFID can be understood completely, it is essential to understand how Radio

Frequency communication occurs. RF (Radio Frequency) communication occurs by the

transference of data over electromagnetic waves. By generating a specific electromagnetic

wave at the source, its effect can be noticed at the receiver far from the source, which then

identifies it and thus the information.

In an RFID system, the RFID tag which contains the tagged data of the object

generates a signal containing the respective information which is read by the RFID reader,

which then may pass this information to a processor for processing the obtained information

for that particular application.

Thus, an RFID System can be visualized as the sum of the following three components:

RFID tag or transponder RFID reader or transceiver Data processing subsystem

Fig 3.5: RFID Module


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An RFID tag is composed of an antenna, a wireless transducer and an encapsulating

material. These tags can be either active or passive. While the active tags have on-chip

power, passive tags use the power induced by the magnetic field of the RFID reader.

An RFID reader consists of an antenna, transceiver and decoder, which sends periodic signals

to inquire about any tag in vicinity. On receiving any signal from a tag it passes on that

information to the data processor. The data processing subsystem provides the means of

processing and storing the data.

RFID Frequencies:

Much like tuning in to the favourite radio station, RFID tags and readers must be

tuned into the same frequency to enable communications. RFID systems can use a variety of

frequencies to communicate, but because radio waves work and act differently at different

frequencies, a frequency for a specific RFID system is often dependant on its

application. High frequency RFID systems (850 MHz to 950 MHz and 2.4 GHz to 2.5 GHz)

offer transmission ranges of more than 90 feet, although wavelengths in the 2.4 GHz range

are absorbed by water, which includes the human body and therefore has limitations.

RFID Design Approach:

Two fundamentally different RFID design approaches exist for transferring powerfrom the reader to the tag: magnetic induction and electromagnetic (EM) wave capture. These

two designs take advantage of the EM properties associated with an RF antennathe near

field and the far field. Both can transfer enough power to a remote tag to sustain its

operationtypically between 10 _W and 1 mW, depending on the tag type.

Near-field RFID:

Faradays principle of magnetic induction is the basis of near-field coupling between

a reader and tag. A reader passes a large alternating current through a reading coil, resulting

in an alternating magnetic field in its locality. If you place a tag that incorporates a smaller

coil (see figure 3) in this field, an alternating voltage will appear across it. If this voltage is

rectified and coupled to a capacitor, a reservoir of charge accumulates, which you can then

use to power the tag chip.

Because any current drawn from the tag coil will give rise to its own small magnetic

fieldwhich will oppose the readers fieldthe reader coil can detect this as a small increase

in current flowing through it. This current is proportional to the load applied to the tags coil

(hence load modulation).


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Thus, if the tags electronics applies a load to its own antenna coil and varies it over

time, a signal can be encoded as tiny variations in the magnetic field strength representing the

tags ID. The reader can then recover this signal by monitoring the change in current through

the reader coil. A further limitation is the energy available for induction as a function of

distance from the reader coil. The magnetic field drops off at a factor of 1/r3, where ris the

separation of the tag and reader, along a center line perpendicular to the coils plane. These

design pressures have led to new passive RFID designs based on far-field communication.

The range for which we can use magnetic induction approximates to c/2f, where c is

a constant (the speed of light) and f is the frequency. Thus, as the frequency of operation

increases, the distance over which near-field coupling can operate decreases. A further

limitation is the energy available for induction as a function of distance from the reader coil.

The magnetic field drops off at a factor of 1/r3, where r is the separation of the tag and

reader, along a center line perpendicular to the coils plane. These design pressures have led

to new passive RFID designs based on far-field communication.

Fig 3.6: Near field communication of RFID

RFID Module and Principle of working:

RFID Reader Module, are also called as interrogators. They convert radio waves

returned from the RFID tag into a form that can be passed on to Controllers, which can make


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use of it. RFID tags and readers have to be tuned to the same frequency in order to

communicate. RFID systems use many different frequencies, but the most common and

widely used & supported by our Reader is 125 KHz.

Fig 3.7: RFID Module inner view

An RFID system consists of two separate components: a tag and a reader. Tags are

analogous to barcode labels and come in different shapes and sizes. The tag contains an

antenna connected to a small microchip containing up to two kilobytes of data. The reader or

scanner functions similarly to a barcode scanner. However, while a barcode scanner uses a

laser beam to scan the barcode, an RFID scanner uses electromagnetic waves. To transmit

these waves, the scanner uses an antenna that transmits a signal communicating with the tags

antenna. The tags antenna receives data from the scanner and transmits its particular chip

information to the scanner.

The data on the chip is usually stored in one of two types of memory. The most

common is Read-Only Memory (ROM), as its name suggests, read-only memory cannot be

altered once programmed onto the chip during the manufacturing process. The second type of

memory is Read/Write Memory, though it is also programmed during the manufacturing

process, it can later be altered by certain devices.

Features of RFID:

Reading collocated tagsOne commercial objective of RFID systems is to read and charge for all tagged

goods in a standard supermarket shopping cart as it is pushed through an instrumented

checkout aisle. Such a system would speed up the checkout process and reduce operational

costs.

Enabling a distributed memory revolutionAnother distinguishing feature of modern RFID is that tags can contain far

more information than a simple ID. They can incorporate additional read only or read-write

memory, which a reader can then further interact with. Read-only memory might containadditional product details that dont need to be read every time a tag is interrogated but are


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available when required. For example, the tag memory might contain a batch code, so if some

products are found to be faulty, the code can help find other items with the same defects.

Tag memory can also be used to enable tags to store self-describing information.

Although a tags unique ID can be used to recover its records in an online database,

communication with the database might not always be possible. For example, if a package is

misdirected during transportation, the receiving organization might not be able to determine

its correct destination. Additional destination information written into the tag would obviate

the need and cost of a fully networked tracking system.

RFID that incorporates sensingOne of the most intriguing aspects of modern RFID tags is that they can convey

information that extends beyond data stored in an internal memory and include data that

onboard sensors created Dynamically.

Commercial versions of RFID technology can already ensure that critical

environmental parameters havent been exceeded. For example, ifa package is dropped on

the floor, the impact might have damaged the enclosed product. A passive force sensor can

supply a single bit of information that can be returned along with an RFID tags ID, alerting

the system about the problem.

Applications of RFID:

Security and Access ControlRFID has long been used as an electronic key to control who has access to office

buildings or areas within office buildings. The first access control systems used low-

frequency RFID tags. Recently, vendors have introduced 13.56 MHz systems that offer

longer read range. The advantage of RFID is it is convenient (an employee can hold up a

badge to unlock a door, rather than looking for a key or swiping a magnetic stripe card) and

because there is no contact between the card and reader, there is less wear and tear, and

therefore less maintenance.

As RFID technology evolves and becomes less expensive and more robust, it's likely

that companies and RFID vendors will develop many new applications to solve common and

unique business problems.


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People TrackingPeople tracking system are used just as asset tracking system. Hospitals and jails are most

general tracking required places. Hospital uses RFID tags for tracking their special patients.

In emergency patient and other essential equipment can easily track. It will be mainly very

useful in mental care hospitals where doctors can track each and every activity of the patient.

Hospitals also use these RFID tags for locating and tracking all the activities of the newly

born babies.

The best use of the people tracking system will be in jails. It becomes an easy tracking

system to track their inmates. Many jails of different US states like Michigan, California, and

Arizona are already using RFID-tracking systems to keep a close eye on jail inmates.

HealthcarePatient safety is a big challenge of healthcare vertical. Reducing medication errors,

meeting new standards, staff shortages, and reducing costs are the plus points of use of RFID

solutions. RFID wristbands containing patient records and medication history address several

of these concerns.

Transportation paymentsGovernments use RFID applications for traffic management, while automotive

companies use various RFID tracking solutions for product management. Many of these

solutions may work together in the future, though privacy regulations prevent many

initiatives from moving forward at the same pace that technology allows.

Promotion trackingManufacturers of products sold through retailers promote their products by

offering discounts for a limited period on products sold to retailers with the expectation that

the retailers will pass on the savings to their customers. However, retailers typically engage

inforward buying, purchasing more product during the discount period than they intend to

sell during the promotion period. Some retailers engage in a form of arbitrage, reselling

discounted product to other retailers, a practice known as diverting.

3.4 Microcontroller

Microcontrollers are widely used in embedded systems products.Microcontroller is a programmable device. A microcontroller has a CPU in addition to a


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fixed amount of RAM, ROM, I/O ports and a timer embedded all on a single chip. The fixed

amount of on-chip ROM, RAM and number of I/O ports in microcontrollers makes them

ideal for many applications in which cost and space are critical.

The Intel 8051 is Harvard architecture, single chip microcontroller (C) which was

developed by Intel in 1980 for use in embedded systems. It was popular in the 1980s and

early 1990s, but today it has largely been superseded by a vast range of enhanced devices

with 8051-compatible processor cores that are manufactured by more than 20 independent

manufacturers including Atmel, Infineon Technologies and Maxim Integrated Products.

8051 is an 8-bit processor, meaning that the CPU can work on only 8 bits of data at

a time. Data larger than 8 bits has to be broken into 8-bit pieces to be processed by the CPU.

8051 is available in different memory types such as UV-EPROM, Flash and NV-RAM.

Features of AT89S52:

RAM is 256 bytes. 8K Bytes of Re-programmable Flash Memory. 4.0V to 5.5V Operating Range. Fully Static Operation: 0 Hz to 33 MHzs Three-level Program Memory Lock. 256 x 8-bit Internal RAM. 32 Programmable I/O Lines. Three 16-bit Timer/Counters. Eight Interrupt Sources. Watchdog timer. Dual data pointer. Fast programming time. Flexible ISP programming (byte and page mode).

Description:

The AT89s52 is a low-voltage, high-performance CMOS 8-bit microcomputer with

8K bytes of Flash programmable memory. The device is manufactured using Atmels high


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density nonvolatile memory technology and is compatible with the industry-standard MCS-

51 instruction set. The on chip flash allows the program memory to be reprogrammed in

system or by a conventional non volatile memory programmer. By combining a versatile 8-

bit CPU with Flash on a monolithic chip, the Atmel AT89s52 is a powerful microcomputer,

which provides a highly 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 contents but freezes the oscillator

disabling all other chip functions until the next hardware reset.

Pin description:

Vcc: Pin 40 provides supply voltage to the chip. The voltage source is +5V.

GND: Pin 20 is the 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-order address/data

bus during accesses to external program and data memory. In this mode, P0 has internal pull-

ups.

Port 0 also receives the code bytes during Flash programming and outputs the code

bytes during Program verification. External pull-ups are required during program verification.


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Fig 3.8: pin diagram of 89S52

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

1 also receives the low-order address bytes during Flash programmingand verification.

Table 3.1: port1 pin description


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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 2 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 uses 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. The port also receives the high-order address

bits and some control signals during Flash programming and verification.

Port 3:

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

buffers can sink/source four TTL inputs. When 1s are written to Port 3 pins, they are pulled

high by the internal pull-ups and can be used as inputs. As inputs, Port 3 pins that are

externally being pulled low will source current (IIL) because of the pull-ups. Port 3 receives

some control signals for Flash programming and verification.

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

in the following table.

Table 3.2: Port3 pin description

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 after the Watchdog times out. The

DISRTO bit in SFR AUXR (address 8EH) can be used to disable this feature. In the defaultstate of bit DISRTO, the RESET HIGH out feature is enabled.


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ALE/PROG:

Address Latch Enable (ALE) is an output pulse for latching the low byte of the

address during accesses to external memory. This pin is also the program pulse input (PROG)

during Flash programming.

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

and 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.

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

When the AT89S52 is executing code from external program memory, PSEN is activated

twice each machine cycle, except that two PSEN activations are skipped during each access

to external data memory.

EA/VPP:

External Access Enable EA must be strapped to GND in order to 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 Flash programming.

XTAL1:

Input to the inverting oscillator amplifier and input to the internal clock operating circuit.

XTAL2:

Output from the inverting oscillator amplifier.


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Fig 3.9: Oscillator connections

Special Function Registers:

A map of the on-chip memory area called the Special Function Register (SFR) space

is shown in the following table.

It should be noted that not all of the addresses are occupied and unoccupied addresses

may not be implemented on the chip. Read accesses to these addresses will in general return

random data, and write accesses will have an indeterminate effect.

User software should not write 1s to these unlisted locations, since they may be used

in future products to invoke new features. In that case, the reset or inactive values of the newbits will always be 0.

Timer 2 Registers:

Control and status bits are contained in registers T2CON and T2MOD for Timer 2.

The register pair (RCAP2H, RCAP2L) is the Capture/Reload register for Timer 2 in 16-bit

capture mode or 16-bit auto-reload mode.

Interrupt Registers:

The individual interrupt enable bits are in the IE register. Two priorities can be set for

each of the six interrupt sources in the IP register.


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Table 3.3: Interrupt Register

Timers:

The 8051 has two timers: Timer 0 and Timer 1. They can be used either as timers to

generate a time delay or as counters to count events happening outside the microcontroller.

Both Timer 0 and Timer 1 are 16-bit wide. Since the 8051 has an 8-bit architecture,

each 16-bit timer is accessed as two separate registers of low byte and high byte.

Lower byte register of Timer 0 is TL0 and higher byte is TH0. Similarly lower byte

register of Timer1 is TL1 and higher byte register is TH1.


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TMOD (timer mode) register:

Both timers 0 and 1 use the same register TMOD to set the various operation modes.

TMOD is an 8-bit register in which the lower 4 bits are set aside for Timer 0 and the upper 4

bits for Timer 1. In each case, the lower 2 bits are used to set the timer mode and the upper 2

bits to specify the operation.

GATE:

Every timer has a means of starting and stopping. Some timers do this by software,

some by hardware and some have both software and hardware controls. The timers in the

8051 have both. The start and stop of the timer are controlled by the way of software by the

TR (timer start) bits TR0 and TR1. These instructions start and stop the timers as long as

GATE=0 in the TMOD register. The hardware way of starting and stopping the timer by an

external source is achieved by making GATE=1 in the TMOD register.

C/T:

Timer or counter selected. Cleared for timer operation and set for counter operation.

Mode Selection:

M1 M0 Mode Operating Mode

0 0 0 13-bit timer mode

8-bit timer/counter THx with TLx as 5-bit prescaler

0 1 1 16-bit timer mode

16-bit timer/counters THx and TLx are cascaded

1 0 2 8-bit auto reload timer/counter

THx holds a value that is to be reloaded into TLx each time

it overflows

1 1 3 Split timer mode

The mode used here to generate a time delay is MODE 2.


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Timer 1:

Timer 1 is identical to timer 0, except for mode 3, which is a hold-count mode. The

following comments help to understand the differences:

Timer 1 functions as either a timer or event counter in three modes of operation. Timer 1s

mode 3 is a hold-count mode.

Timer 1 is controlled by the four high-order bits of the TMOD register and bits 2, 3, 6 and 7

of the TCON register. The TMOD register selects the method of timer gating (GATE1), timer

or counter operation (C/T1#) and mode of operation (M11 and M01). The TCON register

provides timer 1 control functions: overflow flag (TF1), run control bit (TR1), interrupt flag

(IE1) and interrupt type control bit (IT1).

Timer 1 can serve as the baud rate generator for the serial port. Mode 2 is best suited for this

purpose.

For normal timer operation (GATE1 = 0), setting TR1 allows TL1 to be incremented by the

selected input. Setting GATE1 and TR1 allows external pin INT1# to control timer operation.

Timer 1 overflow (count rolls over from all 1s to all 0s) sets the TF1 flag generating an

interrupt request.

When timer 0 is in mode 3, it uses timer 1s overflow flag (TF1) and run control bit (TR1).

For this situation, use timer 1 only for applications that do not require an interrupt (such as a

baud rate generator for the serial port) and switch timer 1 in and out of mode 3 to turn it off

and on.

It is important to stop timer/counter before changing modes.

Mode 2 (8-bit Timer with Auto Reload):

Mode 2 configures Timer 1 as an 8-bit timer (TL1) with automatic reload from the

TH1 register on overflow. TL1 overflow sets the TF1 flag in the TCON register and reloads

TL1 with the contents of TH1, which is preset by software. The reload leaves TH1

unchanged.


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Fig 3.10: Timer in mode2

SCON (serial control) register:

The SCON register is an 8-bit register used to program the start bit, stop bit and data

bits of data framing.

SM0 SCON.7 Serial port mode specifier

SM1 SCON.6 Serial port mode specifier

SM2 SCON.5 Used for multiprocessor communication

REN SCON.4 Set/cleared by software to enable/disable reception

TB8 SCON.3 Not widely used

RB8 SCON.2 Not widely used

TI SCON.1 Transmit interrupt flag. Set by hardware at the

beginning of the stop bit in mode 1. Must be

cleared by software.

RI SCON.0 Receive interrupt flag. Set by hardware at the

beginning of the stop bit in mode 1. Must be

cleared by software.


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SM0 SM1

0 0 Serial Mode 0

0 1 Serial Mode 1, 8-bit data, 1 stop bit, 1 start bit

1 0 Serial Mode 2

1 1 Serial Mode 3

Of the four serial modes, only mode 1 is widely used. In the SCON register, when serial

mode 1 is chosen, the data framing is 8 bits, 1 stop bit and 1 start bit, which makes it

compatible with the COM port of IBM/ compatible PCs. And the most important is serial

mode 1 allows the baud rate to be variable and is set by Timer 1 of the 8051. In serial mode

1, for each character a total of 10 bits are transferred, where the first bit is the start bit,

followed by 8 bits of data and finally 1 stop bit.

Interrupts:

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. These

interrupts are all shown in the below figure.

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. The below table shows that bit position IE.6 is unimplemented.

User software should not write a 1 to this bit position, since it may be used in future AT89

products.

Timer 2 interrupt is generated by the logical OR of bits TF2 and EXF2 in register

T2CON. Neither of these flags is cleared by hardware when the service routine is vectored to.

In fact, the service routine may have to determine whether it was TF2 or EXF2 that generated

the interrupt, and that bit will have to be cleared in software.

The Timer 0 and Timer 1 flags, TF0 and TF1, are set at S5P2 of the cycle in which

the timers overflow. The values are then polled by the circuitry in the next cycle. However,

the Timer 2 flag, TF2, is set at S2P2 and is polled in the same cycle in which the timer

overflows.


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Table 3.4: Interrupt Enable Register

3.5. LCD (LIQUID CRYSTAL DISPLAY)

LCD stands for Liquid Crystal Display. LCD is finding wide spread use replacing LEDs

(seven segment LEDs or other multi segment LEDs) because of the following reasons:

1. The declining prices of LCDs.2. The ability to display numbers, characters and graphics. This is in contrast to LEDs,

which are limited to numbers and a few characters.

3. Incorporation of a refreshing controller into the LCD, thereby relieving the CPU ofthe task of refreshing the LCD. In contrast, the LED must be refreshed by the CPU to

keep displaying the data.

4. Ease of programming for characters and graphics.These components are specialized for being used with the microcontrollers, which

means that they cannot be activated by standard IC circuits. They are used for writing

different messages on a miniature LCD.


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Fig 3.11: LCD Display

Automatic shifting message on display (shift left and right), appearance of the pointer,

backlight etc. are considered as useful characteristics.

Pins Functions:

There are pins along one side of the small printed board used for connection to the

microcontroller. There are total of 14 pins marked with numbers (16 in case the background

light is built in). Their function is described in the table below:

Function Pin

Number

Name Logic

State

Description

Ground 1 Vss - 0V

Power supply 2 Vdd - +5VContrast 3 Vee - 0Vdd

Control of

operating

4 RS 0

1

D0 D7 are interpreted as

commands

D0D7 are interpreted as data

5 R/W 0

1

Write data (from controller to

LCD)

Read data (from LCD to

controller)

6 E 0

1

From 1to 0

Access to LCD disabled

Normal operating

Data/commands are transferredto LCD

Data /

commands

7 D0 0/1 Bit 0 LSB

8 D1 0/1 Bit 1

9 D2 0/1 Bit 2

10 D3 0/1 Bit 3

11 D4 0/1 Bit 4

12 D5 0/1 Bit 5

13 D6 0/1 Bit 6

14 D7 0/1 Bit 7 MSB

Table 3.5: LCD Display


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LCD screen:

LCD screen consists of two lines with 16 characters each. Each character consists of

5x7 dot matrix. Contrast on display depends on the power supply voltage and whether

messages are displayed in one or two lines. For that reason, variable voltage 0-Vdd is applied

on pin marked as Vee. Trimmer potentiometer is usually used for that purpose. Some

versions of displays have built in backlight (blue or green diodes). When used during

operating, a resistor for current limitation should be used (like with any LE diode).

3.6 RS232 CABLE

To allow compatibility among data communication equipment, an interfacing

standard called RS232 is used. Since the standard was set long before the advent of the TTL

logic family, its input and output voltage levels are not TTL compatible. For this reason, to

connect any RS232 to a microcontroller system, voltage converters such as MAX232 are

used to convert the TTL logic levels to the RS232 voltage levels and vice versa.

The RS232 connector was originally developed to use 25 pins. In this DB25

connector pin out provisions were made for a secondary serial RS232 communication

channel. In practice, only one serial communication channel with accompanying handshaking

is present. Only very few computers have been manufactured where both serial RS232

channels are implemented. Examples of this are the Sun SPARCstation 10 and 20 models and

the Dec Alpha Multia.

Fig 3.12:RS232 Cable


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3.7 MAX232 IC

Max232 IC is a specialized circuit which makes standard voltages as required by

RS232 standards. This IC provides best noise rejection and very reliable against dischargesand short circuits. MAX232 IC chips are commonly referred to as line drivers.

To ensure data transfer between PC and microcontroller, the baud rate and voltage

levels of Microcontroller and PC should be the same. The voltage levels of microcontroller

are logic1 and logic 0 i.e., logic 1 is +5V and logic 0 is 0V. But for PC, RS232 voltage levels

are considered and they are: logic 1 is taken as -3V to -25V and logic 0 as +3V to +25V. So,

in order to equal these voltage levels, MAX232 IC is used. Thus this IC converts RS232

voltage levels to microcontroller voltage levels and vice versa.

Fig 3.13: MAX232


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5. CONCLUSION

The implementation of staff attendance system using RFID module using

microcontroller is done successfully. The communication is properly done without any

interference between different modules in the design. Design is done to meet all the

specifications and requirements. Software tools like Keil uvision Simulator, Proload to dump

the source code into the microcontroller, Orcad Lite for the schematic diagram have been

used to develop the software code before realizing the hardware. The performance of the

system is more efficient. The reader reads the tag information when the object along with the

tag is brought near it and passes the data to the controlling unit. Reading the information sent

by the reader and displaying it on the LCD is the main job of the microcontroller. The

mechanism is controlled by the microcontroller.

Circuit is implemented in Orcad and implemented on the microcontroller

board. The performance has been verified both in software simulator and hardware design.

The total circuit is completely verified functionally. It can be concluded that the design

implemented in the present work provide portability, flexibility and the data transmission is

also done with low power consumption.


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6. FUTURE SCOPE

RFID is said by many in the industry to be the frontrunner technology for

automatic identification and data collection. The biggest, as of yet unproven, benefit would

ultimately be in the consumer goods supply chain where an RFID tag attached to a consumer

product could be tracked from manufacturing to the retail store right to the consumer's home.

Many see RFID as a technology in its infancy with an untapped potential. While we may talk

of its existence and the amazing ways in which this technology can be put to use, until there

are more standards set within the industry and the cost of RFID technology comes down we

won't see RFID systems reaching near their full potential anytime soon.


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REFERENCES

Mohammad Ali Mazidi, The 8051 Microcontroller And Embedded SystemsUsing Assembly And C, Second Edition.

KENNETH J.AYALA, 8051 Microcontroller Architecture, programming andapplications.

http://www.8051projects.net/keil-c-programming-tutorial/introduction.php. http://www.atmel.com/dyn/resources/prod_documents/doc1919.pdf http://www.kpsec.freeuk.com/components/relay.htm


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APPENDIX

A.Software implementationSoftware tools required:

Keil v3, Proload are the two software tools used to program microcontroller. The

working of each software tool is explained below in detail.

Programming Microcontroller:

A compiler for a high level language helps to reduce production time. To program the

AT89S52 microcontroller the Keil v3 is used. The programming is done strictly in the

embedded C language. Keil v3 is a suite of executable, open source software development

tools for the microcontrollers hosted on the Windows platform.

The compilation of the C program converts it into machine language file (.hex). This

is the only language the microcontroller will understand, because it contains the original

program code converted into a hexadecimal format. During this step there are some warnings

about eventual errors in the program.

Keil compiler:

Keil compiler is software used where the machine language code is written and

compiled. After compilation, the machine source code is converted into hex code which is to

be dumped into the microcontroller for further processing. Keil compiler also supports C

language code.


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Fig 4.1: Compilation of source code

Proload:

Proload is software which accepts only hex files. Once the machine code is converted

into hex code, that hex code has to be dumped into the microcontroller and this is done by the

Proload. Proload is a programmer which itself contains a microcontroller in it other than the

one which is to be programmed. This microcontroller has a program in it written in such a

way that it accepts the hex file from the Keil compiler and dumps this hex file into the

microcontroller which is to be programmed. As the Proload programmer kit requires power

supply to be operated, this power supply is given from the power supply circuit designed

above. It should be noted that this programmer kit contains a power supply section in the

board itself but in order to switch on that power supply, a source is required. Thus this is

accomplished from the power supply board.


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Fig 4.2:Atmel8051 device programmer


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B.Sample code

#include

#include"lcddisplay.h"

#include

sbit sw = P2^2;

sbit buz = P2^7;

code unsigned char card1[]="300022C431E7";

code unsigned char card2[]="300022A140F3";

code unsigned char card3[]="300022939415";

unsigned char modem[15],j=0;

/*serial interrupt function***/

void serintr(void) interrupt 4

{

if(RI==1)

{

modem[j]=SBUF;

j=j+1;

RI=0;

}


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}

void main()

{

unsigned char count=0,pswd=0,c1=0,c2=0,c3=0;

delay(50);

lcd_init();

TMOD=0x20; // select timer 1 in mode2

TH1=0xFD; // load the timer for generating 9600 baud rate

SCON=0x50; // select the serial communication 8bit data 1 start and 1 stop bit mode

TR1=1; // start the timer

EA=1; //enable global interrupt

ES=1; //enable serial interrupt

start:

lcdcmd(0x1);

msgdisplay("WELCOME");

lcdcmd(0x01); //clear the lcd

msgdisplay("SHOW THE CARD");

while(j==0) //check any cardv is detected or not

{

if(sw==0) //if switch is pressed then duisplay the obsenties

{

lcdcmd(0x01);

if((c1)&&(c2)&&(c3))


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{

msgdisplay("No absenties..");

while(1);

}

msgdisplay("absenties..");

lcdcmd(0xc0);

if(c1==0)

{

msgdisplay("Raj ");

}

if(c2==0)

{

msgdisplay("Sai ");

}

if(c3==0)

{

msgdisplay("Ram ");

}

while(1);

}

}

while(1)

{


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if(!strcmp(modem,card1)) //check the carddata with all existance data

{

lcdcmd(1);//clear the lcd

msgdisplay("Welcome Mr Raj");

buz=0; //buzzer on

delay(1000);

buz=1; //buzzer off

c1=1; //update the attandance

goto start;

}

if(!strcmp(modem,card2))

{

lcdcmd(1);

msgdisplay("Welcome Mr Sai");

buz=0;

delay(1000);

buz=1;

c2=1;

goto start;

}

if(!strcmp(modem,card3))

{

lcdcmd(1);


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msgdisplay("Welcome Mr Ram");

buz=0;

delay(1000);

buz=1;

c3=1;

goto start;

}

else //if not matched then unauthorised

{

buz=0;

lcdcmd(1);

msgdisplay("Unauthorised!!");

delay(2000);

buz=1;

goto start;

}

}

}


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staff attendance using rfid module

Documents