chapters,reference (1)

1 SMART WALKING STICK

DEPARTMENT OF ECE JCET

CHAPTER 1

INTRODUCTION

Blindness or visual impairment is a condition that affects many people around the world. This

condition leads to the loss of the valuable sense of vision. Worldwide more than 160 million

people are visually impaired with 37 million to be blind. The need for assistive devices was and

will be continuous. There is a wide range of navigation systems and tools existing for visually

impaired individuals.

The blind navigation system caters needs of the blind people who are not able to move from one

place to another without the help of others. Recent survey source uncovered that India has now

become the country with world‟s largest number of blind people. There are 37 million blind

people across the globe, over them 15 million people are from India. The usage of the blind

navigation system is very less and inefficient in India. The blind travellers depend on other

guides like blind canes, people information, trained dogs, etc. Visual function can be classified

by four tiers: normal vision, moderate visual impairment, severe impairment, and complete

blindness. Legally blind refers to a person who has less than 20/200 vision in either eye, or a

limited field of vision. Many virtually impaired people use walking sticks and guide dogs to

move from place to place.

For this visually impaired population, the goal is often to complete tasks in the least obstructive

method, rather than the most efficient method, including the use of guide dogs and walking

sticks. A guide dog is trained to steer its users away from objects and barriers. When a visually

impaired person is using a walking stick, they gain a sense of their surroundings by waving their

walking stick and striking obstacles ahead of them. Public locations, such as a crowded shopping

malls, airports, train stations, and bus stations, can be difficult to navigate and can be become

disorienting for those with visual impairments. Imagine having to navigate to a terminal at an

airport without the ability to see. After checking in bags and getting through security, one would



still need to walk to the terminal listed on their ticket. Without asking others for help, these tasks

can be difficult. These public spaces contain various sensory distractions such as traffic noise

and other people. For a visually impaired person, it can become difficult to determine what

direction to travel without some form of guidance.

The main objective is to provide a talkative assistance to blind people. This project develops an

intelligent system that works efficiently well indoor .This focuses on designing a device for

visually impaired people that help them to travel independently and is comfortable to use. The

proposed device is used for guiding individuals who are blind or partially sighted. The device is

used to help blind people to move with the same ease and confidence as a sighted people. RFID

can be installed into public building and it is also integrated into blind person‟s walking stick.

The whole device is designed to be small and is used in conjunction with the white cane.

The scope of this project is to develop a low-cost system that assist the blind and visually

impaired without the help of sighted person. RFID is used in indoor to assist the blind people

since GPS cannot be used efficiently indoor.



CHAPTER 2

LITERATURE SURVEY

2.1 TALKING ASSISTANCE ABOUT LOCATION FINDING BOTH

INDOOR AND OUTDOOR FOR BLIND PEOPLE

[Nandhini.N , Vinoth chakkaravarthy.G , G.Deepa Priya IJIRSET 2014]

The RFID is used for indoor location detection and it is attached to the walking unit and an RFID

tag is installed on all the areas that need to be identified. These tags will serve as a landmark to

the person using the cane. Every tag will be equipped with as much information as needed to

clearly define the location of that precise tag (i.e. restaurant, shops). The tag will also incorporate

additional information concerning direction and locations of other sensitive location (i.e. Bus

station, subway station and phone boots). The tag will be covered by a protective shield to keep

it safe from any harm.

2.2 ENHANCED INDEPENDENCE FREE PATH DETECTOR TO BLIND

PEOPLE

[Mr.B.Anbazhagan1, Mr.V.Nandagopal IJAREEIE 2013]

In the proposed system a device based on optics is designed. The device includes a near-IR LED

and a photodiode. The LED emits a train of pulses. These pulses strike the obstacle, and the light

is detected by the photodiode. The light detected is processed to determine whether there is a

path or not. The LED emits pulses managed by a control unit. The control unit consists of a

microcontroller and optic coupler Circuit. The control unit increases the amplitude of the pulse

step by step. The received amplitude is checked and if it is greater than the threshold, vibration is

produced using a DC motor and indicated using voice IC. The absence of vibration indicates that

a free path is available. The absence of path is also sent as a message to the care taker using

GSM modem. This system only served as an obstacle detector and not for path identification.



2.3 AUTOMATED MOBILITY AND ORIENTATION SYSTEM FOR

BLIND OR PARTIALLY SIGHTED PEOPLE

[Abdel Ilah Nour Alshbata 2013]

Historically, there are various types of assistive technologies that are currently available to blind

or visually impaired people. One example is the smart phone, which addresses some of the

concerns that the blind and partially sighted people needed in their daily life. The smart phones

allow those people to listen to voice mails and even write and send emails. Another example

refers to the electronic oriented aids, is the laser or ultrasonic. In this technology, energy waves

are emitted ahead, and then it is reflected from obstacles in the path of the user and detected by a

matching sensor. Thus, the distance to the obstacle is calculated according to the time variance

between the two signals. Wearable and portable assistive technologies are also used for assisting

people with disabilities such as the blind. Wearable devices are allowing hands-free interaction,

or at least minimizing the use of hands when using the device, while portable assistive devices

required a constant hand interaction. Wearable technology is achieved by devices that are

actually worn on the body such as: assistive devices worn on fingers and hands, assistive devices

worn on the wrist and forearm, assistive devices worn on the tongue, head-mounted assistive

devices, vests and belts, and assistive devices worn on the feet. Despite efforts and the great

variety of wearable assistive devices available, user acceptance is quite low and the white cane

will continue to be the most assistive devices for the blind.

2.4 RADIO -FREQUENCY IDENTIFICATION

Radio-frequency identification (RFID) is a wireless technology that uses low frequency radio

fields to transfer small bits of data between RFID devices, usually consisting of chips attached to

tags and a receiver with an antenna. RFID is a popular technology that is being used in a variety

of fields, such as retail. RFID devices can be compared to bar codes or magnetic strips on credit

cards, where each bar code or strip is a unique identifier represented by a number. And, similar

to bar codes and magnetic strips, the device must be scanned by the receiver to obtain

information from the RFID chip. One benefit to RFID technology over previously mentioned

forms of identification is that RFID devices operate by proximity rather than swiping or



scanning. Usually RFID devices can be read or scanned from as far as 100 meters to as little as a

few centimeters depending on the type and range of the readers and chips. Since RFID

technology is susceptible to reader and tag collision, the exact frequencies of RFID tags are

variable and can be configured to minimize interference from other electronics, including other

RFID systems.

Early use of RFID technology can be traced to the 1940s. A predecessor to RFID devices and

receivers was originally used as an espionage tool for the Soviet Union to identify friendly or foe

fighter planes as they landed on runways. This technology was crude, but it functioned similarly

to passive RFID: once activated the tag would retransmit the radio waves containing the plane‟s

information to another device. The modern form of RFID technology was developed by Mario

Cardullo in 19737. He designed a passive RFID system with memory. Early potential uses were

in automotive identification, banking, highway tolls, and medical sciences. As RFID matured,

different types of tags and receivers emerged. There are multiple types of RFID devices: active,

semi-passive, and passive RFID. Active RFID chips have an internal battery and actively

broadcasts their signals and are often used for applications such as management, money

transactions, product tracking, access control, promotion tracking, etc. Semi-passive RFID chips

also use internal batteries to power their circuits however unlike active chips which actively

broadcast their signal, these chips rely on the receiver to supply power to broadcast the signal.

Due to the costs of both the battery and advanced internal hardware, both these types of RFID

technology are typically expensive and are reserved for more advanced forms of asset

management. Passive RFID is a more budget friendly alternative to active and semi passive

RFID. Passive chips or tags do not have internal batteries; therefore the cost of maintenance is

drastically lowered since there is no need for replacement batteries. Instead, the circuits obtain

power when they are scanned by the receiver. The passive chips do not broadcast their

frequencies and must be within a few centimetres to be scanned by the receiver. This has its

benefits and draw backs as well. While the ranges of the tags are fairly small, there is a smaller

chance of frequency collision.



CHAPTER 3

SYSTEM ANALYSIS

3.1 EXISTING SYSTEM

Blind stick is an innovative stick designed for visually disabled people for improved navigation.

It allows visually challenged people to navigate with ease using ultrasonic technology. The blind

stick is integrated with ultrasonic sensor along with light and water sensing. The project first uses

ultrasonic sensors to detect obstacles ahead using ultrasonic waves. On sensing obstacles the

sensor passes this data to the microcontroller. The microcontroller then processes this data and

calculates if the obstacle is close enough. If the obstacle is not that close the circuit does nothing.

If the obstacle is close the microcontroller sends a signal to sound a buzzer. It also detects and

sounds a different buzzer if it detects water and alerts the blind. One more feature is that it allows

the blind to detect if there is light or darkness in the room. The system has one more advanced

feature integrated to help the blind find their stick if they forget where they kept it. A wireless

RF based remote is used for this purpose. Pressing the remote button sounds a buzzer on the stick

which helps the blind person to find their stick. Thus this system allows for obstacle detection as

well as finding stick if misplaced by visually disabled people.

An ultrasonic sensor is a device that works in much same way as RADAR and SONAR. In fact,

ultrasonic sensors mimic bats and other animals‟ natural ability to use ultrasonic frequencies for

navigation. Ultrasonic sensors broadcast a powerful, ultrasonic frequency, then detect the

ultrasonic sound waves as they bounce off of objects and return to the sensor. They are almost

always used to measure speed or direction and are efficiently at determining position. Ultrasonic

sensors are commonly used for a wide variety of noncontact presence, proximity, or distance

measuring applications. These devices typically transmit a short burst of ultrasonic sound toward

a target, which reflects the sound back to the sensor. The system then measures the time for the

echo to return to the sensor and computes the distance to the target using the speed of sound in

the medium



3.2 PROPOSED SYSTEM

There are 285 million people worldwide that have some level of visual impairment. Legally

blind refers to a person who has less than 20/200 vision in either eye, or a limited field of

vision3. While not all visually impaired individuals are completely blind, many use walking

sticks and guide dogs to navigate from place to place and to gain a sense of their surroundings.

For this visually impaired population, the goal is often to complete tasks in the least obstructive

method, rather than the most efficient method, including the use of guide dogs and walking

sticks. A guide dog is trained to steer its users away from objects and barriers. When a visually

impaired person is using a walking stick, they gain a sense of their surroundings by waving their

walking stick and striking obstacles ahead of them.

Public locations, such as a crowded shopping malls, airports, train stations, and bus stations, can

be difficult to navigate and can be become disorienting for those with visual impairments.

Imagine having to navigate to a terminal at an airport without the ability to see. After checking in

bags and getting through security, one would still need to walk to the terminal listed on their

ticket. Without asking others for help, these tasks can be difficult. These public spaces contain

various sensory distractions such as traffic noise and other people. For a visually impaired

person, it can become difficult to determine what direction to travel without some form of

guidance. Navigating through unfamiliar public locations has long been a source of difficulty for

the blind. The goal of this project is to provide a technological solution for the visually impaired

to travel through public locations easily. The use of technology in assisting the visually impaired

has increased over the years. Various groups have researched ways to improve the accessibility

of public locations for individuals with disabilities. Only recently has there been increased

interest in assistive technology for those with visual impairments. Utilizing the project team‟s

programming experience; the team designed a technical solution to visually impaired navigation

in public places.

The navigational aid created is a radio frequency identification (RFID) antenna embedded into a

walking stick. Combining RFID technology and the walking stick used by many visually

impaired individuals, a navigational system was developed that can be integrated into the life of

a visually impaired individual without the need for learning a new device. The user holds a

walking stick with an embedded RFID receiver. Scanning tags with the receiver provides



location data to the program for which the user can input a command. Once a RFID reader picks

up a tag, the user will be able to receive their current location and also directions to a new

location within the layout of RFID tags. This paper describes how this solution was

implemented, from conception to design, testing, and results.

The paper outlines the project undertaken in developing prototype of Radio Frequency

Identification walking stick. The device intended to assist the blind during walking on a

sidewalk. Many of the blind people used the traditional method like dog and old design of

walking stick as their guide to walk on the sidewalk. The limitation of this method is the blind

people must walk closely to the border of the sidewalk and use the walking stick to find out their

current location. This will be exposing the blind to the risk like fallout from the sidewalk. The

application of RFID will enhance the conventional method in term of detecting and estimating

the distance between the blind and the sidewalk border. The project objective is to develop a

walking stick prototype by utilizing Radio Frequency Identification (RFID). This paper also

describes a RFID function and its components explicitly a tag, reader and middleware include a

relevant frequency for RFID. The experimental works intended in this project will cover antenna

polarization, tag performance, tag orientation sensitivity and tag communication distance for

radio frequency. The project also includes development of hardware, software and integration of

hardware and software.



3.3 BLOCK DIAGRAM AND DESCRIPTION

PATH TO DESTINATION

Figure 3.2: Block Diagram

3.3.1 RFID READER

Radio-frequency identification (RFID) is the wireless use of electromagnetic fields to transfer

data, for the purposes of automatically identifying and tracking tags attached to objects. The tags

contain electronically stored information. Some tags are powered by electromagnetic induction

magnetic fields produced near the reader. Some types collect energy from the interrogating radio

waves and act as a passive transponder. Other types have a local power source such as a battery

and may operate at hundreds of meters from the reader. Unlike a barcode, the tag does not



necessarily need to be within line of sight of the reader and may be embedded in the tracked

object.

RFID tags are used in many industries. For example, an RFID tag attached to an automobile

during production can be used to track its progress through the assembly line; RFID-tagged

pharmaceuticals can be tracked through warehouses; and implanting RFID microchips in

livestock and pets allows positive identification of animals. Since RFID tags can be attached to

cash, clothing, and possessions, or implanted in animals and people, the possibility of reading

personally-linked information without consent has raised serious privacy concerns.

3.3.2 MICROCONTROLLER (AT89S52)

AT89S52 has 4 different ports, each one having 8 Input/output lines providing a total of 32 I/O

lines. Those ports can be used to output DATA and orders do other devices, or to read the state

of a sensor, or a switch. Most of the ports of the 89S52 have 'dual function' meaning that they

can be used for two different functions. The first one is to perform input/output operations and

the second one is used to implement special features of the microcontroller like counting external

pulses, interrupting the execution of the program according to external events, performing serial

data transfer or connecting the chip to a computer to update the software. Each port has 8 pins,

and will be treated from the software point of view as an 8-bit variable called 'register', each bit

being connected to a different input/output pin.

There are two different memory types: RAM and EEPROM. Shortly, RAM is used to store

variable during program execution, while the EEPROM memory is used to store the program

itself, that's why it is often referred to as the 'program memory'. It is clear that the CPU (Central

Processing Unit) is the heart of the micro controllers. It is the CPU that will Read the program

from the FLASH memory and execute it by interacting with the different peripherals.



Figure 3.3 Pin configuration of AT89S52

Diagram above shows the pin configuration of the AT89S52, where the function of each pin is

written next to it, and, if it exists, the dual function is written between brackets. Note that the

pins that have dual functions can still be used normally as an input/output pin. Unless the

program uses their dual functions, all the 32 I/O pins of the microcontroller are configured as

input/output pins.

3.3.3 APR9600 IC

The APR9600 device offers true single-chip voice recording, non-volatile storage, and playback

capability for 40 to 60 seconds. The device supports both random and sequential access of

multiple messages .Sample rates are user-selectable, allowing designers to customize their design

for unique quality and storage time needs. Integrated output amplifier, microphone amplifier, and

AGC circuits greatly simplify system design. the device is ideal for use in portable voice

recorders, toys, and many other consumer and industrial applications. APLUS integrated

achieves these high levels of storage capability by using its proprietary analog/multilevel storage

technology implemented in an advanced Flash non-volatile memory process, where each

memory cell can store 256 voltage levels. This technology enables the APR9600 device to



reproduce voice signals in their natural form. It eliminates the need for encoding and

compression, which often introduce distortion.

3.3.4 TAGS

RFID tagging is an ID system that uses small radio frequency identification devices for

identification and tracking purposes. An RFID tagging system includes the tag itself, a read/write

device, and a host system application for data collection, processing, and transmission. An RFID

tag (sometimes called an RFID transponder) consists of a chip, some memory and

an antenna .RFID tags that contain their own power source are known as active tags. Those

without a power source are known as passive tags. A passive tag is briefly activated by the radio

frequency (RF) scan of the reader. The electrical current is small -- generally just enough for

transmission of an ID number. Active tags have more memory and can be read at greater ranges.

Increasingly, RFID tagging is used in supply chain management as an alternative to bar code

technology. Although more expensive to use than the bar code stickers, RFID tags don't get dirty

or fall off or require an unobstructed line-of-sight between the tag and the reader. There are

almost endless possible uses for RFID tagging. Injectable ID chips have been used to track

wildlife and livestock for over a decade. An injectable RFID tag called the VeriChip can be used

to help medical personnel identify a patient who is unable to speak -- and even provide access to

the person's medical records.



CHAPTER 4

SYSTEM DESCRIPTION

4.1 CIRCUIT DIAGRAM AND WORKING

Figure 4.1: Circuit diagram of smart walking stick

The entire system works on a 9v battery. The operating voltage of all components present in

the circuit is 5v which is obtained by connecting a 7805 voltage regulator to the battery. An

additional battery charging circuit is set up for charging the battery. The battery charging

circuit consists of a step down transformer (TRAN-2P2S), which converts 230v AC voltage

into 12v AC voltage. The bridge full wave rectifier converts 12v AC voltage into 12v DC

XTAL218

XTAL119

ALE30

EA31

PSEN29

RST9

P0.0/AD039

P0.1/AD138

P0.2/AD237

P0.3/AD336

P0.4/AD435

P0.5/AD534

P0.6/AD633

P0.7/AD732

P1.0/T21

P1.1/T2EX2

P1.23

P1.34

P1.45

P1.56

P1.67

P1.78

P3.0/RXD10

P3.1/TXD11

P3.2/INT012

P3.3/INT113

P3.4/T014

P3.7/RD17

P3.6/WR16

P3.5/T115

P2.7/A1528

P2.0/A821

P2.1/A922

P2.2/A1023

P2.3/A1124

P2.4/A1225

P2.5/A1326

P2.6/A1427

U1

AT89S52

C127p

11.0592 MHZ

27p

X1

CRYSTAL

R108.2k

C310uf

RESET

TR1

TRAN-2P2S

D1DIODE

D2DIODE

D3DIODE

D4DIODE

C41000u

VI

1V

O3

GND2

U27809

230 v AC12 v AC

9v D

C

D7

14D

613

D5

12D

411

D3

10D

29

D1

8D

07

E6

RW

5R

S4

VS

S1

VD

D2

VE

E3

LCD1LM016L

R1 10k

R2 10k

R3 10k

R4 10k

R5 10k

R6 10k

R7 10k

R8 10k

CHANNEL 1

CHANNEL 2

CHANNEL 3

CHANNEL 4

CHANNEL 5

CHANNEL 6

CHANNEL 7

CHANNEL 8

APR 9600 BOARD

REC/ PLAY

+

-

LS1

SPEAKER

Microphone

RXD

RTS

TXD

CTS

RFID READER

BATTERY CHARGING CIRCUIT

VI

1V

O3

GND2

U27805

BATTERY

5 V



voltage. The 1000uf capacitor removes all the ripples present in the output of the bridge

rectifier. 12v DC voltage is regulated 9v DC voltage by using LM7809 voltage regulator. The

charging circuit is connecting to the battery in the walking stick.

The smart walking stick uses AT89S52 microcontroller. The crystal oscillator is connected to

the 18th

(XTAL2) and 19th

(XTAL1) pin of the microcontroller. The oscillator controls the

speed of the system and it also generates the clock signals for the microcontroller. Every

microcontroller starts its operation when the clock signal is generated. The crystal oscillator

consists of two 27pF capacitors and a 11.0592MHz crystal. The resetting circuit is used to

reset the previous operations of the microcontroller. The reset circuit is connected to the

ground through 8.2k resistor. The reset push button and the 10uF capacitor are connected to

the VCC. The resetting circuit is connected to the 9th pin of the microcontroller. The VCC is

connected to the external access enable pin of the microcontroller used for the internal

program execution. The 8 I/O lines of the port1 of AT89S52 are connecting to the APR9600

IC. APR9600 has 8 channels. The APR9600 IC with an inbuilt microphone is connected to a

speaker. 10th pin, serial input port-3.0 of microcontroller is connected to the TXD of the

RFID reader.Port-0 and Port-2 of AT89S52 is connected to the LCD display.

RFID stands for radio frequency identification device. AT89S52 sends a restart command to

the RFID reader. RFID reader has specific RFID tags. When RFID reader receives the signal

from the microcontroller, the reader starts the search for the RFID tags. Each tag has a unique

code. When SCK command is enabled the RFID reader stores the data. The RFID reader

responds and send FOUND signal to the AT89S52 indicating that the tag is successfully read.

Each code has a particular voltage. The pin goes high for that particular voltage. Then

command for that voltage is stored. APR9600 IC is recorded with certain commands like turn

right, turn left etc. When signal from the microcontroller is received by the APR9600, the

recorded voice outputs through the speaker. According to the output commands the blind or

partially sighted persons can navigate through the tag positions.



4.2 HARDWARE EXPLANATION

4.2.1 BRIDGE RECTIFIER

Figure4.2: Bridge rectifier

In full wave bridge rectifier a transformer and four diodes are used. During the positive half

cycle of secondary voltage, the diodes D2 and D4 are forward biased, but diodes D1 and D3 do

not conduct. The current is through D2, R, D4 and secondary winding. During the negative half

cycle the diodes D1 and D3 are forward biased, but diodes D2 and D4 do not conduct. The

current is through D1, secondary winding, D3 and R. The load current is in the same direction in

both half cycles. Therefore a unidirectional (d. c.) voltage is obtained across load resistor. Since

each diode conducts for only one hale cycle, the current rating (Io) of the diodes must be at least

– half of the dc load current. i.e. 0.5 Idc. Each diode must withstand a peak inverse voltage equal

to the peak secondary voltage. PIV =Vp. Therefore the PIV rating of the diodes must be greater

than Vp. As the output is a full wave signal, the output frequency is double the input frequency.

The maximum efficiency of bridge rectifier is 81.2%.

ADVANTAGES OF BRIDGE RECTIFIER:

Centre tap on the secondary of the transformer is not necessary.

Small transformer can be used.

For a bridge rectifier circuit PIV per diode is one half of the value for each diode in a full



wave rectifier.

DISADVANTAGES OF BRIDGE WAVE RECTIFIER:

In this type two extra diodes are used.

The voltage regulation is poor.

4.2.2 RESISTOR

Figure 4.3: Resistors

A resistor is a passive two-terminal electrical component that implements electrical resistance as

a circuit element. Resistors reduces current flow, and, at the same time, act to lower voltage

levels within circuits. Resistors may have fixed resistances or variable resistances, such as those

found in thermistors, varistors, trimmers, photo resistors and potentiometers. The current through

a resistor is in direct proportion to the voltage across the resistor's terminals. This relationship is

represented by Ohm's law:

where I is the current through the conductor in units of amperes, V is the potential difference

measured across the conductor in units of volts, and R is the resistance of the conductor in units

of ohms (symbol: Ω).



The ratio of the voltage applied across a resistor's terminals to the intensity of current in the

circuit is called its resistance, and this can be assumed to be a constant (independent of the

voltage) for ordinary resistors working within their ratings. Resistors are common elements of

electrical networks and electronic circuits and are ubiquitous in electronic equipment. Practical

resistors can be composed of various compounds and films, as well as resistance wires (wire

made of a high-resistivity alloy, such as nickel-chrome). Resistors are also implemented within

integrated circuits, particularly analog devices, and can also be integrated into hybrid and printed

circuits. The electrical functionality of a resistor is specified by its resistance: common

commercial resistors are manufactured over a range of more than nine orders of magnitude.

When specifying that resistance in an electronic design, the required precision of the resistance

may require attention to the manufacturing tolerance of the chosen resistor, according to its

specific application. The temperature coefficient of the resistance may also be of concern in

some precision applications. Practical resistors are also specified as having a maximum power

rating which must exceed the anticipated power dissipation of that resistor in a particular circuit:

this is mainly of concern in power electronics applications. Resistors with higher power ratings

are physically larger and may require heat sinks. In a high-voltage circuit, attention must

sometimes be paid to the rated maximum working voltage of the resistor. While there is no

minimum working voltage for a given resistor, failure to account for a resistor's maximum rating

may cause the resistor to incinerate when current is run through it.

4.2.3 CAPACITOR

Figure 4.4: Capacitor

A capacitor (originally known as a condenser) is a passive two-terminal electrical component

used to store energy electro statically in an electric field. The forms of practical capacitors vary

widely, but all contain at least two electrical conductors (plates) separated by a dielectric (i.e.,



insulator). The conductors can be thin films of metal, aluminum foil or disks, etc. The 'non

conducting' dielectric acts to increase the capacitor's charge capacity. A dielectric can be glass,

ceramic, plastic film, air, paper, mica, etc. Capacitors are widely used as parts of electrical

circuits in many common electrical devices. Unlike a resistor, a capacitor does not dissipate

energy. Instead, a capacitor stores energy in the form of an electrostatic field between its plates.

When there is a potential difference across the conductors (e.g., when a capacitor is attached

across a battery), an electric field develops across the dielectric, causing positive charge (+Q) to

collect on one plate and negative charge (-Q) to collect on the other plate. If a battery has been

attached to a capacitor for a sufficient amount of time, no current can flow through the capacitor.

However, if an accelerating or alternating voltage is applied across the leads of the capacitor, a

displacement current can flow. An ideal capacitor is characterized by a single constant value for

its capacitance. Capacitance is expressed as the ratio of the electric charge (Q) on each conductor

to the potential difference (V) between them. The SI unit of capacitance is the farad (F), which is

equal to one coulomb per volt (1 C/V). Typical capacitance values range from about 1 pF (10−12

F) to about 1 mF (10−3

F).The capacitance is greater when there is a narrower separation between

conductors and when the conductors have a larger surface area. In practice, the dielectric

between the plates passes a small amount of leakage current and also has an electric field

strength limit, known as the breakdown voltage. The conductors and leads introduce an

undesired inductance and resistance.

4.2.4 IC AT89S52

Figure 4.5 AT89S52

The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K bytes of

in-system programmable Flash memory. The on-chip Flash allows the program memory to be

reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a



versatile 8-bit CPU with in-system programmable Flash on a monolithic chip, the Atmel

AT89S52 is a powerful microcontroller which provides a highly-flexible and cost effective

solution to many embedded control applications. The device is manufactured using Atmel‟s

high-density nonvolatile memory technology and is compatible with the Indus-try-standard

80C51 instruction set and pin out. The on-chip Flash allows the program memory to be

reprogrammed in-system or by a conventional nonvolatile memory pro-grammar. By combining

a versatile 8-bit CPU with in-system programmable Flash on a monolithic chip, the Atmel

AT89S52 is a powerful microcontroller which provides a highly-flexible and cost-effective

solution to many embedded control applications. The AT89S52 provides the following standard

features: 8K bytes of Flash, 256 bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers,

three 16-bit timer/counters, a six-vector two-level interrupt architecture, a full duplex serial port,

on-chip oscillator, and clock circuitry. In addition, the AT89S52 is designed with static logic for

operation down to zero frequency and supports two software selectable power saving modes. The

Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port, and interrupt

system to continue functioning. The Power-down mode saves the RAM con-tents but freezes the

oscillator, disabling all other chip functions until the next interrupt hardware reset

4.2.5 IC APR9600

Figure 4.6: APR9600 IC

The APR9600 device offers true single-chip voice recording, non-volatile storage and playback

capability for 40 to 60 seconds. The device supports both random and sequential access of

multiple messages. Sample rates are user selectable, allowing designers to customize their design

for unique quality and storage time needs. Integrated output amplifier, microphone amplifier, and

AGC circuits greatly simplify system design. The device is ideal for use importable voice



recorders, toys, and many other consumer and industrial applications. APLUS integrated

achieves these high levels of storage capability by using its proprietary analog/multilevel storage

technology implemented in an advanced Flash non-volatile memory process, where each

memory cell can store 256 voltage levels. This technology enables the APR9600 device to

reproduce voice signals in their natural form. It eliminates the need for encoding and

compression, which often introduce distortion.

.

• Single-chip, high-quality voice recording & playback solution

- No external ICs required

- Minimum external components

• Non-volatile Flash memory technology

- No battery backup required

• User-Selectable messaging options

- Random access of multiple fixed-duration messages

- Sequential access of multiple variable-duration messages

• User-friendly, easy-to-use operation

- Programming & development systems not required

- Level-activated recording & edge-activated playback switches

• Low power consumption

- Operating current: 25 mA typical

- Standby current: 1 uA typical

- Automatic power-down

• Chip Enable pin for simple message expansion

4.2.6 EM-18 RFID READER AND TAGS

The EM-18 RFID Reader module operating at 125kHz is an inexpensive solution for the RFID

based applications. The Reader module comes with an on-chip antenna and can be powered up

with a 5V power supply.



Figure 4.7: RFID Reader

This RFID Reader has a Serial RS-232 output which makes it easy to interface it to any

microcontroller or computer. It also has TTL output pins which can be connected to the

microcontroller. The reader senses any RFID tag within the reading distance and outputs the tag

data through both serial RS-232 connection and through TTL pins. Power-up the module initially

and connect the transmit pin of the module to receive pin of the microcontroller. Then show the

card within the reading distance so that the card number is thrown at the output. Optionally the

module can be configured for also a weigand output. This RFID Reader Module 125 KHz is easy

to use. It is low cost. Its built-in onboard noise reduction circuitry and its small sized factor make

it ideal for a variety of applications, limited only by the imagination of the user. Use it for time

and attendance management, access control, inventory tracking, car immobilization, robotics, etc

Voltage:5V DC

Electrical current: <50mA

operating frequency: 125KHZ

Read distance：10CM

Size: 32 mm (length), 32 mm (width), 8 mm(height)

4.2.7 VOLTAGE REGULATOR

Regulator is a device which provides constant output voltage with varying input voltage. There

are two types of regulators-

(a) Fixed voltage regulator (b) adjustable voltage regulator



We have used fixed voltage regulator LM78XX last two digits signify output voltage. The

voltage for our system is 5V that is why we have used 7805 regulator which provides 5V from

12V dc. This is a 3 terminal voltage regulator and is shown below,

Fig 4.8: Voltage Regulator

Output indication:

We use LED to observe the functioning of our system. If the LED glows it confirms proper

functioning of our supply.

4.2.7 LCD DISPLAY

FIG 4.9: LCD pin diagram

Liquid crystal display (LCD) is an electronically-modulated optical device shaped into a thin, flat

panel made up of any number of color or monochrome pixels filled with liquid crystals and



arrayed in front of a light source (backlight) or reflector. It is often utilized in battery-powered

electronic devices because it uses very small amounts of electric power. Each pixel of an LCD

typically consists of a layer of molecules aligned between two transparent electrodes, and two

polarizing filters, the axes of transmission of which are (in most of the cases) perpendicular to

each other. With no actual liquid crystal between the polarizing filters, light passing through the

first filter would be blocked by the second (crossed) polarizer.

FIG: 4.10 LCD

The main principle behind liquid crystal molecules is that when an electric current is applied

to them, they tend to untwist. This causes a change in the light angle passing through them.

This causes a change in the angle of the top polarizing filter with respect to it. So, little light is

allowed to pass through that particular area of LCD. Thus that area becomes darker comparing

to others. For making an LCD screen, a reflective mirror has to be setup in the back. An

electrode plane made of indium-tin oxide is kept on top and a glass with a polarizing film is

also added on the bottom side. The entire area of the LCD has to be covered by a common

electrode and above it should be the liquid crystal substance.

Fig 4.11: Working Principle of LCD



Pin description

Function Name

1 Ground (0V) Ground

2 Supply voltage; 5V (4.7V – 5.3V) Vcc

3 Contrast adjustment; through a variable resistor VEE

4 Selects command register when low; and data register when high

Register Select

5 Low to write to the register; High to read from the register Read/write

6 Sends data to data pins when a high to low pulse is given Enable

7

8-bit data pins

DB0

8 DB1

9 DB2

10 DB3

11 DB4

12 DB5

13 DB6

14 DB7

15 Backlight VCC (5V) Led+

16 Backlight Ground (0V) Led-

Table 4.1 Pin description of LCD



CHAPTER 5

DESIGN AND SOFTWARE ANALYSIS

5.1 BATTERY CHARGING CIRCUIT DESIGN

Component List:

1. Step down transformer

2. Voltage regulator

3. Capacitors

4. Diodes

Voltage regulator:

Required voltage 5V is obtained using LM7805 IC

7805 IC Rating:

Input voltage range 7V- 35V

Current rating Ic = 1A

Output voltage range VMax=5.2V ,VMin=4.8V

Transformer:

Selecting a suitable transformer is of great importance. The current rating and the secondary

voltage of the transformer is a crucial factor.

The current rating of the transformer depends upon the current required for the load to be

driven.

The input voltage to the 7805 IC should be at least 2V greater than the required 2V

output; therefore it requires an input voltage at least close to 7V.



So I chose a 6-0-6 transformer with current rating 1 amp.

Rectifying circuit:

The best is using a full wave rectifier

Its advantage is DC saturation is less as in both cycle diodes conduct.

Higher Transformer Utilization Factor (TUF).

1N4007 diodes are used as its is capable of withstanding a higher reverse voltage of

1000v whereas 1N4001 is 50V

Capacitors:

Knowledge of Ripple factor is essential while designing the values of capacitors

It is given by

Y=1/(4√3fRC) (as the capacitor filter is used)

1. f= frequency of AC ( 50 Hz)

2. R=resistance calculated

R= V/Ic

V= secondary voltage of transformer

V=12√2=16.9v

R=16.9/1=16.9Ω standard 18Ω chosen

3. C= filtering capacitance

We have to determine this capacitance for filtering

Y=Vac-rms/Vdc

Vac-rms = Vr/2√3

Vdc= VMax-(Vr/2)

Vr= VMax- VMin



Vr = 0. 4V

Vac-rms = .3464V

Vdc = 5V

Y=0 .072

Hence the capacitor value is found out by substituting the ripple factor in Y=1/(4√3fRC)

Thus, C= 1856 µF and standard 1000µF is chosen

5.2 SOFTWARE ANALYSIS

5.2.1 INTRODUCTION TO EMBEDDED C

There are various types of embedded systems. Be it a digital camera or a mobile phone or a

washing machine, all of them has some kind of processor functioning inside it. Associated with

each processor is the embedded software. If hardware forms the body of an embedded system,

embedded processor acts as the brain, and embedded software forms its soul. It is the embedded

software which primarily governs the functioning of embedded systems.

During infancy years of microprocessor based systems, programs were developed using

assemblers and fused into the EPROMs. There used to be no mechanism to find what the

program was doing. LEDs, switches, etc. were used to check correct execution of the program.

Some „very fortunate‟ developers had In-circuit Simulators (ICEs), but they were too costly and

were not quite reliable as well.

As time progressed, use of microprocessor-specific assembly-only as the programming language

reduced and embedded systems moved onto C as the embedded programming language of

choice. C is the most widely used programming language for embedded processors/controllers.

Assembly is also used but mainly to implement those portions of the code where very high

timing accuracy, code size efficiency, etc. are prime requirements.

Initially C was developed by Kernighan and Ritchie to fit into the space of 8K and to write

(portable) operating systems. Originally it was implemented on UNIX operating systems. As it

was intended for operating systems development, it can manipulate memory addresses. Also, it

allowed programmers to write very compact codes. This has given it the reputation as the

language of choice for hackers too.



As assembly language programs are specific to a processor, assembly language didn‟t offer

portability across systems. To overcome this disadvantage, several high level languages,

including C, came up. Some other languages like PLM, Modula-2, Pascal, etc. also came but

couldn‟t find wide acceptance. Amongst those, C got wide acceptance for not only embedded

systems, but also for desktop applications. Even though C might have lost its sheen as

mainstream language for general purpose applications, it still is having a strong-hold in

embedded programming. Due to the wide acceptance of C in the embedded systems, various

kinds of support tools like compilers & cross-compilers, ICE, etc. came up and all this facilitated

development of embedded systems using C.

5.2.2 EMBEDDED SYSTEMS PROGRAMMING

Embedded systems programming is different from developing applications on a desktop

computers. Key characteristics of an embedded system, when compared to PCs, are as

follows: Embedded devices have resource constraints (limited ROM, limited RAM and stack

space, less processing power). Components used in embedded system and PCs are different;

embedded systems typically uses smaller, less power consuming components. · Embedded

systems are more tied to the hardware.

Two salient features of Embedded Programming are code speed and code size. Code speed is

governed by the processing power, timing constraints, whereas code size is governed by

available program memory and use of programming language. Goal of embedded system

programming is to get maximum features in minimum space and minimum time.

Embedded systems are programmed using different type of languages:

Machine Code

Low level language, i.e., assembly

High level language like C, C++, Java, Ada, etc.

Application level language like Visual Basic, scripts, Access, etc.

Assembly language maps mnemonic words with the binary machine codes that the processor

uses to code the instructions. Assembly language seems to be an obvious choice for



programming embedded devices. However, use of assembly language is restricted to developing

efficient codes in terms of size and speed. Also, assembly codes lead to higher software

development costs and code portability is not there. Developing small codes are not much of a

problem, but large programs/projects become increasingly difficult to manage in assembly

language. Finding good assembly programmers has also become difficult nowadays. Hence high

level languages are preferred for embedded systems programming.

Use of C in embedded systems is driven by following advantages:

It is small and reasonably simpler to learn, understand, program and debug.

C Compilers are available for almost all embedded devices in use today, and there is

a large pool of experienced C programmers. Unlike assembly, C has advantage of

processor-independence and is not specific to any particular microprocessor/

microcontroller or any system. This makes it convenient for a user to develop

programs that can run on most of the systems.

As C combines functionality of assembly language and features of high level

languages, C is treated as a „middle-level computer language‟ or „high level

assembly language‟

It is fairly efficient. It supports access to I/O and provides ease of management of

large embedded projects.

5.2.3 FLOW CHART

The flow chart for the programme executed is depicted below. In the programme used for

executing smart walking system, four tags were used. Tag 1, tag 2 tag 3, tag 4 were assigned the

variables w,x,y,z respectively. When the blind passes the tags for the first time tags are assigned

a zero value and the first instruction is outputted as audio and then when the blind passes the tag

for the second time the tags assigned the value 1 and instruction stored for that value is

outputted. This is repeated for all the four tags respectively according to the instructions stored

for each tag.



Fig 5.1: Flow chart



CHAPTER 6

RESULT AND DISCUSSION

The project on “smart walking stick” was successfully completed. It was a wonderful experience

as the basic knowledge on different steps in circuit manufacturing such as PCB fabrication,

soldering components, programming, circuit testing and debugging was attained which will be

surely helpful in an electronics engineer‟s career. It can be used in public places like airport,

shopping malls, railway stations etc. It is mainly used in indoor applications.

The smart walking stick finds its application in path detection. It has more advantages as

compared to the existing system. In existing system the walking stick was only used for obstacle

detection. This drawback is nullified in the proposed system. The advantages are less cost and

easy implementation. Nowadays blind mobility is one of the major problems facing in society,

this RFID based smart walking stick can overcome this problems.



CONCLUSION AND FUTURE SCOPE

A new intelligent system for guiding individuals who are blind or partially sighted was

developed. The system is used to enable blind people to move with the same ease and confidence

as a sighted people. The system can be linked with a RFID module to pin-point the location of

the blind person and to establish a two way communication path in a wireless fashion. Moreover,

it can be made to provide the direction information as well as information to avoid obstacles

based on ultrasonic sensors. A beeper, an accelerometer sensor and vibrator can be also added to

the system. The whole system is designed to be small, light and is used in conjunction with the

white cane. The results have shown that the blinds that used this system could move

independently and safely.

The proposed works for future includes wearable equipment which consists of head hat and mini

hand stick to help the blind person to navigate alone safely and to avoid any obstacles that may

be encountered, whether fixed or mobile, to prevent any possible accident. The main component

of this system is the infrared sensor which is used to scan a predetermined area around blind by

emitting-reflecting waves. The reflected signals received from the barrier objects are used as

inputs to PIC microcontroller. The microcontroller is then used to determine the direction and

distance of the objects around the blind. It also controls the peripheral components that alert the

user about obstacle's shape, material, and direction. The implemented system is cheap, fast, and

easy to use and an innovative affordable solution to blind and visually impaired people in third

world countries.



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