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Mini-project report Automated Toll Collection with Complex Security System

BRECW, Hyderabad Page 1

Chapter 1

Introduction

1.1 Introduction:

The project aims automated toll collection system using the active RFID tags,

vehicles are made to pass through a sensor system that is embedded on the highway just

before the tollgate. The system will electronically classify the vehicle and calculate the

exact amount to be paid by the vehicle owner, ensuring no pilferage of the toll amount.

1.2 Objective of the project:

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

application. The main objective of this project is to design a system that continuously

checks for the RFID and controls the Toll Gate and collects the exact fare from the

owner of vehicle and reduces the man power with accurate toll collection.

This project is a device that collects data from the RFID section, codes the data

into a format that can be understood by the controlling section. This receiving section

controls the direction of the motor and updates the amount as per the command

received from the RFID section.

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

consists of a RF Reader and Tag, microcontroller and the robotic arrangement.

1.3Background of the Project:

The software application and the hardware implementation help the

microcontroller read the data from RFID Tag and accordingly change the direction of

the rotation of the motor. The measure of efficiency is based on how fast themicrocontroller can read the data, detect the signal received and change the direction of

the rotation of the motor. The system is totally designed using RFID and embedded

systems technology. The performance of the design is maintained by controlling unit.


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Chapter 2

Overview of the technologies used

2.1 Embedded Systems:

An embedded system can be defined as a computing device that does a specific

focused job. Appliances such as the air-conditioner, VCD player, DVD player, printer,

fax machine, mobile phone etc. are examples of embedded systems. Each of these

appliances will have a processor and special hardware to meet the specific requirement

of the application along with the embedded software that is executed by the processor

for meeting that specific requirement.The embedded software is also called firm ware. The desktop/laptop

computer is a general purpose computer. You can use it for a variety of applications

such as playing games, word processing, accounting, software development and so on.

In contrast, the software in the embedded systems is always fixed.

Embedded systems do a very specific task, they cannot be programmed to do

different things. Embedded systems have very limited resources, particularly the

memory. Generally, they do not have secondary storage devices such as the CDROM

or the floppy disk. Embedded systems have to work against some deadlines. A specific

job has to be completed within a specific time. In some embedded systems, called real-

time systems, the deadlines are stringent. Missing a deadline may cause a catastrophe-

loss of life or damage to property. Embedded systems are constrained for power. As

many embedded systems operate through a battery, the power consumption has to be

very low.

Some embedded systems have to operate in extreme environmental conditions

such as very high temperatures and humidity.

Following are the advantages of Embedded Systems:

1. They are designed to do a specific task and have real time performance

constraints which must be met.

2. They allow the system hardware to be simplified so costs are reduced.

3. They are usually in the form of small computerized parts in larger devices

which serve a general purpose.


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4. The program instructions for embedded systems run with limited computer

hardware resources, little memory and small or even non-existent keyboard or

screen.

2.2 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.

2.3 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 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: 2.1 Three different RFID tags they come in all shapes and sizes.


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Chapter 3

Hardware Implementation of the Project

This chapter briefly explains about the Hardware Implementation of the project.

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 P89V51RD2 microcontroller.

It also explains the various modules used in this project.

3.1 Project Design:

The implementation of the project design can be divided in two parts.

Hardware implementation

Firmware implementation

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.

The firmware part deals in programming the microcontroller so that it can

control the operation of the ICs used in the implementation. In the present work, we

have used the Orcad design software for PCB circuit design, the Keil v3 software

development tool to write and compile the source code, which has been written in the C

language. The Proload programmer has been used to write this compile code into the

microcontroller. The firmware implementation is explained in the next chapter.

The project design and principle are explained in this chapter using the block

diagram and circuit diagram. The block diagram discusses about the required

components of the design and working condition is explained using circuit diagram and

system wiring diagram.

3.1.1 Block Diagram of the Project and its 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, section and

LCD. The brief description of each unit is explained as follows.


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Fig 3.2 Components of a regulated power supply

3.2.1 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 Microcontrollers:

Microprocessors and microcontrollers are widely used in embedded systems

products. Microcontroller is a programmable device. A microcontroller has a CPU in

addition to a fixed amount of RAM, ROM, I/O ports and a timer 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.

Features of P89V51RD2:

80C51 CPU

5 V operating voltage from 0 MHz to 40 MHz 16/32/64 kB of on-chip flash user code memory with ISP and IAP

Supports 12-clock (default) or 6-clock mode selection via software or ISP

SPI and enhanced UART

PCA with PWM and capture/compare functions

Four 8-bit I/O ports with three high-current port 1 pins (16 mA each)

Three 16-bit timers/counters

Programmable watchdog timer

Eight interrupt sources with four priority levels

Second DPTR register


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Low EMI mode (ALE inhibit)

TTL- and CMOS-compatible logic levels

Fig 3.3 Pin diagram

3.3.1 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.

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

programming and verification.


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Table 3.3.1 Description of pins of port 1

Port 2:

Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 2 outputbuffers 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 P89V51RD2, as shown in the

following table.


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Table 3.3.2 Description of pins of port 3

RST:

Reset input 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 default state of bit DISRTO, the RESET HIGH out feature is

enabled.

ALE/PROG (Address Latch Enable) 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 oscillatorfrequency and may be used for external timing or clocking purposes. 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) is the read strobe to external program memory.

When the P89V51RD2 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.


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XTAL1 Input to the inverting oscillator amplifier and input to the internal clock

operating circuit.

XTAL2 Output from the inverting oscillator amplifier.

Fig 3.3.1 Oscillator connections

Fig 3.3.2 External clock drive configuration

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

amplifier that can be configured for use as an on-chip oscillator. Either a quartz crystal

or ceramic resonator may be used. To drive the device from an external clock source,XTAL2 should be left unconnected while XTAL1 is driven. There are no requirements

on the duty cycle of the external clock signal, since the input to the internal clocking

circuitry is through a divide-by-two flip-flop, but minimum and maximum voltage high

and low time specifications must be observed.

3.4 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 areoccupied 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.


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3.5 Memory Organization:

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

Up to 64K bytes each of external Program and Data Memory can be addressed.

3.5.1 Program Memory:

If the EA pin is connected to GND, all program fetches are directed to external

memory. On the P89V51RD2, 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.

3.5.2 Data Memory:

The P89V51RD2 implements 256 bytes of on-chip RAM. The upper 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. Instructions which use direct addressing access the

SFR space.

For example, the following direct addressing instruction accesses the SFR at

location 0A0H (which is P2). MOV 0A0H, #data

The instructions that use indirect addressing access the upper 128 bytes of

RAM. For example, the following indirect addressing instruction, where R0 contains

0A0H, accesses the data byte at address 0A0H, rather than P2 (whose address is

0A0H).MOV @R0, #data. It should be noted that stack operations are examples of

indirect addressing, so the upper 128 bytes of data RAM are available as stack space.

3.6 Power saving modes of operation:

8051 has two power saving modes. They are:

1. Idle Mode

2. Power Down mode.

The two power saving modes are entered by setting two bits IDL and PD in the

special function register (PCON) respectively.


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The structure of PCON register is as follows.

PCON: Address 87H

The schematic diagram for 'Power down' mode and 'Idle' mode is given as follows:

Fig 3.6 Schematic diagram for power down and idle mode implementation

3.6.1 Idle Mode:

Idle mode is entered by setting IDL bit to 1 (i.e., IDL=1). The clock signal is

gated off to CPU, but not to interrupt, timer and serial port functions. SP, PC, PSW,

Accumulator and other registers maintain their data during IDLE mode. The port pins

hold their logical states they had at the time Idle was initialized. ALE and PSEN (bar)

are held at logic high levels.

Ways to exit Idle Mode:

1. Activation of any enabled interrupt will clear PCON.0 bit and hence the Idle Mode is

exited. The program goes to the Interrupt Service Routine (ISR). After RETI is

executed at the end of ISR, the next instruction will start from the one following the

instruction that enabled the Idle Mode.

2. A hardware reset exits the idle mode. The CPU starts from the instruction following

the instruction that invoked the Idle mode.

3.6.2 Power Down Mode:

The Power Down Mode is entered by setting the PD bit to 1. The internal clock to the

entire microcontroller is stopped. However, the program is not dead. The Power down

Mode is exited (PCON.1 is cleared to 0) by Hardware Reset only. The CPU starts from

the next instruction where the Power down Mode was invoked. Port values are not

changed/ overwritten in power down mode. Vcc can be reduced to 2V in Power down


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Mode. However Vcc has to be restored to normal value before Power down Mode is

exited.

Table 3.6 Status of External pins during Idle and Power down Modes

3.7 Programming the FlashParallel Mode:

The P89V51RD2 is shipped with the on-chip Flash memory array ready to be

programmed. The programming interface needs a high-voltage (12-volt) program

enable signal and is compatible with conventional third-party Flash or EPROM

programmers. The P89V51RD2 code memory array is programmed byte-by-byte.

3.7.1 Programming Algorithm:

Before programming the P89V51RD2, the address, data and control signals

should be set up according to the Flash Programming Modes. To program the

P89V51RD2, take the following steps:

1. Input the desired memory location on the address lines.

2. Input the appropriate data byte on the data lines.

3. Activate the correct combination of control signals.

4. Raise EA/VPP to 12V.

5. Pulse ALE/PROG once to program a byte in the Flash array or the lock bits.

The byte write cycle is self-timed and typically takes no more than 50 s. Repeat steps

1 through 5, changing the address and data for the entire array or until the end of the

object file is reached.

3.7.2 Serial Programming Algorithm

To program and verify the P89V51RD2 in the serial programming mode, the

following sequence is recommended:

1. Power-up sequence:

a. Apply power between VCC and GND pins.

b. Set RST pin to H.

If a crystal is not connected across pins XTAL1 and XTAL2, apply a 3 MHz to

33 MHz clock to XTAL1 pin and wait for at least 10 milliseconds.


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2. Enable serial programming by sending the Programming Enable serial

instruction to pin MOSI/P1.5. The frequency of the shift clock supplied at pin

SCK/P1.7 needs to be less than the CPU clock at XTAL1 divided by 16.

3. The Code array is programmed one byte at a time in either the Byte or Page

mode. The write cycle is self-timed and typically takes less than 0.5 ms at 5V.

4. Any memory location can be verified by using the Read instruction which

returns the content at the selected address at serial output MISO/P1.6.

5. At the end of a programming session, RST can be set low to commence

normal device operation.

Fig 3.7 Programming the flash memory

After Reset signal is high, SCK should be low for at least 64 system clocks

before it goes high to clock in the enable data bytes. No pulsing of Reset signal is

necessary. SCK should be no faster than 1/16 of the system clock at XTAL1.

For Page Read/Write, the data always starts from byte 0 to 255. After the

command byte and upper address byte are latched, each byte thereafter is treated as

data until all 256 bytes are shifted in/out. Then the next instruction will be ready to bedecoded.


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Chapter 4

Radio Frequency Identification

4.1 RFID principles:

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

into two classes: active and passive.

Fig 4.1 RFID devices

1. 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.

2. 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.

4.2 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.


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4.4 RFID Design Approach:

Two fundamentally different RFID design approaches exist for transferring

power from 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 10W and 1 mW, depending on the tag

type.

4.4.1Near-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 this voltage is rectified

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

to power the tag chip.

Tags that use near-field coupling send data back to the reader using load

modulation. 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).

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.

Fig 4.4 Near power mechanism of RFID tags operating at less than 10MHz

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


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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.

4.5 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 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 4.5 RFID module

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.


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4.6 Features of RFID:

4.6.1 Reading collocated tags:

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

operational costs.

Enabling a distributed memory revolution

Another 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

contain additional product details that dont need to be read every time a tag is

interrogated but are 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.

4.6.2 Privacy concerns:

RFID has received much attention in recent years as journalists, technologists

and privacy advocates have debated the ethics of its use. Privacy advocates are

concerned that even though many of the corporations considering RFID use for

inventory tracking have honorable intentions, without due care, the technology might

be unwittingly used to create undesirable outcomes for many customers.

4.6.3 Application Areas:

RFID, Radio Frequency Identification is a technology, which includes wireless

data capture and transaction processing. Proximity (short range) and Vicinity (long

range) are two major application areas where RFID technology is used. Track and trace

applications are long range or vicinity applications. This technology provides additional

functionality and benefits for product authentication. Access control applications are

Short range or proximity type of applications. Agile Sense Technologies is focused on


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delivering innovative, high value RFID solutions assisting companys track assets,

people and documents. Agile Sense provides robust and complete RFID solutions built

On top of its extensible middleware/ framework for Government, Healthcare,

Manufacturing and Aerospace industries.

4.6.4 Current and Potential Uses of RFID:

4.6.4.1 People Tracking:

People 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.

4.6.4.2 Healthcare:

Patient 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.

4.6.4.3 Promotion tracking:

Manufacturers 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 in forward 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. To combat this practice, manufacturers are exploring the use of RFID tags

on promoted merchandise so that they can track exactly which product has sold through

the supply chain at fully discounted prices.


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4.6.5 Manufacturing:

RFID has been used in manufacturing plants for more than a decade. It's used to

track parts and work in process and to reduce defects, increase throughput and manage

the production of different versions of the same product.

4.7 Serial Communication:

The main requirements for serial communication are:

1. Microcontroller

2. PC

3. RS 232 cable

4. MAX 232 IC

5. HyperTerminal

When the pins P3.0 and P3.1 of microcontroller are set, UART which is inbuilt

in the microcontroller will be enabled to start the serial communication.

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.

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


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In serial communication, the data is sent one bit at a time. The 8051 has serial

communication capability built into it, thereby making possible fast data transfer using

only a few wires.

The fact that serial communication uses a single data line instead of the 8-bit

data line instead of the 8-bit data line of parallel communication not only makes it

cheaper but also enables two computers located in two different cities to communicate

over the telephone.

Serial data communication uses two methods, asynchronous and synchronous.

The synchronous method transfers a block of data at a time, while the asynchronous

method transfers a single byte at a time. With synchronous communications, the two

devices initially synchronize themselves to each other, and then continually send

characters to stay in sync. Even when data is not really being sent, a constant flow of

bits allows each device to know where the other is at any given time. That is, each

character that is sent is either actual data or an idle character. Synchronous

communications allows faster data transfer rates than asynchronous methods, because

additional bits to mark the beginning and end of each data byte are not required. The

serial ports on IBM-style PCs are asynchronous devices and therefore only support

Asynchronous serial communications .Asynchronous means "no synchronization", and

thus does not require sending and receiving idle characters. However, the beginning

and end of each byte of data must be identified by start and stop bits. The start bit

indicates when the data byte is about to begin and the stop bit signals when it ends. The

requirement to send these additional two bits causes asynchronous communication to

be slightly slower than synchronous however it has the advantage that the processor

does not have to deal with the additional idle characters.

There are special IC chips made by many manufacturers for serial data

communications (universal asynchronous receiver-transmitter) and USART(universal

synchronous-asynchronous receiver-transmitter). The 8051 has a built-in UART.

In the asynchronous method, the data such as ASCII characters are packed

between a start and a stop bit. The start bit is always one bit, but the stop bit can be one

or two bits. The start bit is always a 0 (low) and stop bit (s) is 1 (high). This is called

framing.

The rate of data transfer in serial data communication is stated as bps (bits per

second). Another widely used terminology for bps is baud rate. The data transfer rate of


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Interfacing max232 with microcontroller:

Fig 4.7.3.1 Interfacing MAX232 with microcontroller

4.7.4 SCON (serial control) register:

The SCON register is an 8-bit register used to program the start bit, stop bit anddata bits of data framing.

Table 4.7.2 Functions of SCON register

SM0 SCON.7 Serial port mode specifier



REN SCON.4 Set or Cleared by software to

enable or 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 bits in mode 1. Must

be cleared by software.


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Table 4.7.3 Modes of Operation of SCON register

SM0 SM1 Mode Of Operation

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.

8051 Interface with any External Devices using Serial Communication:

Fig: 4.7.4 8051 Interface with any external devices using serial communication


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4.8 Switches and Pushbuttons:

This is the simplest way of controlling appearance of some voltage on

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

these components operate.

Fig 4.8 Switches and Push button

This is about something commonly unnoticeable when using these components in

everyday life. It is about contact bounce, a common problem with mechanical switches.

If contact switching does not happen so quickly, several consecutive bounces can be

noticed prior to maintain stable state. The reasons for this are: vibrations, slight rough

spots and dirt. Anyway, this whole process does not last long (a few micro- or

milliseconds), but long enough to be registered by the microcontroller. Concerning the

pulse counter, error occurs in almost 100% of cases.

Fig 4.8.1 Connection between reset pin and micro controller

The simplest solution is to connect simple RC circuit which will suppress each

quick voltage change. Since the bouncing time is not defined, the values of elements

are not strictly determined. In the most cases, the values shown on figure are sufficient.

If complete safety is needed, radical measures should be taken. The circuit (RS

flip-flop) changes logic state on its output with the first pulse triggered by contact

bounce. Even though this is more expensive solution (SPDT switch), the problem is

definitely resolved. Besides, since the condensator is not used, very short pulses can be

also registered in this way. In addition to these hardware solutions, a simple software


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solution is also commonly applied. When a program tests the state of some input pin

and finds changes, the check should be done one more time after certain time delay. If

the change is confirmed, it means that switch (or pushbutton) has changed its position.

The advantages of such solution are: it is free of charge, effects of disturbances are

eliminated and it can be adjusted to the worst-quality contacts.

4.8.1 Switch Interfacing with 8051:

In 8051 PORT 1, PORT 2 & PORT 3 have internal 10k Pull-up resistors

whereas this Pull-up resistor is absent in PORT 0. Hence PORT 1, 2 & 3 can be directly

used to interface a switch whereas we have to use an external 10k pull-up resistor for

PORT 0 to be used for switch interfacing or for any other input. Figure 4.8 shows

switch interfacing for PORT 1, 2 & 3.Shows switch interfacing to PORT 0.

Fig: 4.8.2 Switch interfacing with ports

For any pin to be used as an input pin, a HIGH (1) should be written to the pin

if the pin will always to be read as LOW.In the above figure, when the switch is not

pressed, the 10k resistor provides the current needed for LOGIC 1 and closure of

switch provides LOGIC 0 to the controller PIN.

4.9 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

of the 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.


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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.

Fig 4.9 LCD display

A model described here is for its low price and great possibilities most frequently

used in practice. It is based on the HD44780 microcontroller (Hitachi) and can display

messages in two lines with 16 characters each. It displays all the alphabets, Greek

letters, punctuation marks, mathematical symbols etc. In addition, it is possible to

display symbols that user makes up on its own. Automatic shifting message on display

(shift left and right), appearance of the pointer, backlight etc. are considered as useful

characteristics.

4.9.1 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:

Table 4.9.1 LCD pin description

FunctionPin

NumberName

Logic

StateDescription

Ground 1 Vss - 0V

Power supply 2 Vdd - +5V

Contrast 3 Vee - 0Vdd

Control of

operating

4 RS0

1

D0 D7 are interpreted as

commands

D0D7 are interpreted as data

5 R/W0

1

Write data (from controller to

LCD)

Read data (from LCD to

controller)


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6 E

0

1

From 1 to

0

Access to LCD disabled

Normal operating

Data/commands are transferred

to 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

4.9.2 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).

Fig 4.9.2 LCD screen

4.9.3 LCD Basic Commands:

All data transferred to LCD through outputs D0-D7 will be interpreted as

commands or as data, which depends on logic state on pin RS:

RS = 1 - Bits D0 - D7 are addresses of characters that should be displayed. Built

in processor addresses built in map of characters and displays corresponding


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symbols. Displaying position is determined by DDRAM address. This address

is either previously defined or the address of previously transferred character is

automatically incremented.

RS = 0 - Bits D0 - D7 are commands which determine display mode.

Table 4.9.3 Description of LCD commands

Command RS RW D7 D6 D5 D4 D3 D2 D1 D0Execution

Time

Clear display 0 0 0 0 0 0 0 0 0 1 1.64mS

Cursor home 0 0 0 0 0 0 0 0 1 x 1.64mS

Entry mode set 0 0 0 0 0 0 0 1 I/D S 40uS

Display on/off control 0 0 0 0 0 0 1 D U B 40uS

Cursor/Display Shift 0 0 0 0 0 1 D/C R/L x X 40uS

Function set 0 0 0 0 1 DL N F x X 40uS

Set CGRAM address 0 0 0 1 CGRAM address 40uS

Set DDRAM address 0 0 1 DDRAM address 40uS

Read BUSY flag (BF) 0 1 BF DDRAM address -

Write to CGRAM or

DDRAM1 0 D7 D6 D5 D4 D3 D2 D1 D0 40uS

Read from CGRAM or

DDRAM 1 1 D7 D6 D5 D4 D3 D2 D1 D0 40uS

4.9.4 LCD Connection:

Depending on how many lines are used for connection to the microcontroller,

there are 8-bit and 4-bit LCD modes. The appropriate mode is determined at the

beginning of the process in a phase called initialization. In the first case, the data are

transferred through outputs D0-D7 as it has been already explained. In case of 4-bit

LED mode, for the sake of saving valuable I/O pins of the microcontroller, there are

only 4 higher bits (D4-D7) used for communication, while other may be left

unconnected.


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Consequently, each data is sent to LCD in two steps: four higher bits are sent

first (that normally would be sent through lines D4-D7), four lower bits are sent

afterwards. With the help of initialization, LCD will correctly connect and interpret

each data received. Besides, with regards to the fact that data are rarely read from LCD

(data mainly are transferred from microcontroller to LCD) one more I/O pin may be

saved by simple connecting R/W pin to the Ground. Even though message displaying

will be normally performed, it will not be possible to read from busy flag since it is not

possible to read from display.

4.9.5 LCD Initialization :

Once the power supply is turned on, LCD is automatically cleared. This process

lasts for approximately 15mS. After that, display is ready to operate. The mode of

operating is set by default. This means that:

1. Display is cleared

2. Mode

DL = 1 Communication through 8-bit interface

N = 0 Messages are displayed in one line

F = 0 Character font 5 x 8 dots

3. Display/Cursor on/off

D = 0 Display off

U = 0 Cursor off

B = 0 Cursor blink off

4. Character entry

ID = 1 Addresses on display are automatically incremented by 1

S = 0 Display shift off

Automatic reset is mainly performed without any problems. If for any reason

power supply voltage does not reach full value in the course of 10mS, display will start

perform completely unpredictably. If voltage supply unit cannot meet this condition or

if it is needed to provide completely safe operating, the process of initialization by

which a new reset enabling display to operate normally must be applied.

Algorithm according to the initialization is being performed depends on whether

connection to the microcontroller is through 4- or 8-bit interface. All left over to be

done after that is to give basic commands and of course- to display messages.


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Fig4.9.4: Procedure on 8-bit initialization

Chapter 5

Firmware Implementation of the project design


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This chapter briefly explains about the firmware implementation of the project.

The required software tools are discussed in section 5.1. Section 5.2 shows the flow

diagram of the project design. It presents the firmware implementation of the project

design.

5.1 Software 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.

5.1.1 Programming Microcontroller:

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

program the P89V51RD2 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. This is shown in Fig 4.1. If there

are no errors and warnings then run the program, the system performs all the required

tasks and behaves as expected the software developed. If not, the whole procedure will

have to be repeated again. Fig 5.2 shows expected outputs for given inputs when run

compiled program.

One of the difficulties of programming microcontrollers is the limited amount

of resources the programmer has to deal with. In personal computers resources such as

RAM and processing speed are basically limitless when compared to microcontrollers.

In contrast, the code on microcontrollers should be as low on resources as possible.

5.1.2 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 5.1: Compilation of source Code

Fig 5.2: Running of the compiled program


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Fig 5.3: Flow chart of Electronic toll collection


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Chapter 6

Results and Discussions

6.1 Results:

Fig 6.1 Electronic toll collection system

The implementation of RFID Toll Plaza 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 U vision Simulator, Flash Magic to dump the


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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. Reading the tag and verifying

the tag information with the already stored data and perform the specified task 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 and is following the application

software. 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.

6.2 Working procedure:

Toll Plaza using RFID is basically an embedded system that makes the things

easy in the toll gate fare collection during the time of toll collection. The project uses

the wireless technology RFID and embedded systems to implement the application.

In this project, the necessary and, up to an extent, the sufficient material, the

vehicle has to carry the tag (RFID tag with the voters details).

RFID tag of the vehicle is the tag that stores the details of the vehicle like the

vehicle name and price of the vehicle etc. At the toll plaza, when asks to open toll gate

to show his tag, he has to bring this card near the RFID reader. The RFID reader reads

the data present in the tag.

Since the aim of the project is to provide security and make the task easy, the

system initially stores the details of the vehicle. Thus, the system after reading the card

(RFID tag), it compares this data with the already stored data in the systems memory.

The details present in the card will be displayed on the LCD.

If this data is present in the systems database and matches with any of the

details, the system allows the vehicle to pass the vehicle from the toll gate. If the data

does not match with any of the details of the systems database, the system immediately

rejects and displays the information.


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6.3 Advantages:

Cost effective

Low power consumption

No line-of-sight contact necessary Speed of an RFID system (almost less than 100ms)

Bidirectional communication

Reliability in tough environments

6.4 Applications:

There are many applications related to RFID. Some of them are

People tracking

Asset tracking

Document tracking

Government library

Health care

6.5 Future Scope of the project:

In the short term, the greater the fraction of automated lanes, the lower will be the

cost of operation (once the capital costs of automating are amortized). In the long term,

the greater the relative advantage that registering and turning one's vehicle into an

electronic-toll one provides, the faster cars will be converted from manual-toll use to

electronic-toll use, and therefore the fewer manual-toll cars will drag down average

speed and thus capacity. Some of the benefits for drivers include

fewer and shorter queues at toll plazas by increasing toll booth service rates

faster and more efficient servicethe customer does not need to stop or have

toll fees on hand

The ability to pay by keeping a balance on the customers account or charging a

registered credit card


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6.6 References:

1.

http://www.rfidjournal.com/faq

2. http://www.technovelgy.com/ct/Technology-Article.asp

3. http://csrc.nist.gov/publications/nistpubs/800-98/SP800-98_RFID-2007.pdf

4. www.ieee.org

5. http://www.taltech.com/TALtech_web/resources/intro-sc.html

6. http://focus.ti.com/lit/ds/symlink/max232.pdf

7. http://www.microdigitaled.com/8051/Software/keil_tusstorial.pdf

8.

Microprocessor and Microcontroller book by S.V. Altaf9. www.keil.com/dd/docs/datashts/philips/p89v51rd2.pdf
http://www.rfidjournal.com/faqhttp://www.technovelgy.com/ct/Technology-Article.asphttp://csrc.nist.gov/publications/nistpubs/800-98/SP800-98_RFID-2007.pdfhttp://www.ieee.org/http://www.taltech.com/TALtech_web/resources/intro-sc.htmlhttp://www.taltech.com/TALtech_web/resources/intro-sc.htmlhttp://www.ieee.org/http://csrc.nist.gov/publications/nistpubs/800-98/SP800-98_RFID-2007.pdfhttp://www.technovelgy.com/ct/Technology-Article.asphttp://www.rfidjournal.com/faq

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