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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
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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.
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DEPARTMENT OF ECE JCET
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.
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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
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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.
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DEPARTMENT OF ECE JCET
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
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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
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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.
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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
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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.
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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
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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.
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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
XTAL2
18
XTAL1
19
ALE
30
EA
31
PSEN
29
RST
9
P0.0/AD0
39
P0.1/AD1
38
P0.2/AD2
37
P0.3/AD3
36
P0.4/AD4
35
P0.5/AD5
34
P0.6/AD6
33
P0.7/AD7
32
P1.0/T2
1
P1.1/T2EX
2
P1.2
3
P1.3
4
P1.4
5
P1.5
6
P1.6
7
P1.7
8
P3.0/RXD
10
P3.1/TXD
11
P3.2/INT0
12
P3.3/INT1
13
P3.4/T0
14
P3.7/RD
17
P3.6/WR
16
P3.5/T1
15
P2.7/A15
28
P2.0/A8
21
P2.1/A9
22
P2.2/A10
23
P2.3/A11
24
P2.4/A12
25
P2.5/A13
26
P2.6/A14
27
U1
AT89S52
C1
27p
11.0592 MHZ
27p
X1
CRYSTAL
R10
8.2k
C3
10uf
RESET
TR1
TRAN-2P2S
D1
DIODE
D2
DIODE
D3
DIODE
D4
DIODE
C4
1000u
VI
1
VO
3
GND
2
U2
7809
230 v AC
12 v AC
9vDC
D7
14
D6
13
D5
12
D4
11
D3
10
D2
9
D1
8
D0
7
E
6
RW
5
RS
4
VSS
1
VDD
2
VEE
3
LCD1
LM016L
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
1
VO
3
GND
2
U2
7805
BATTERY
5 V
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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.
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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
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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).
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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.,
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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
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DEPARTMENT OF ECE JCET
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
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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.
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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
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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
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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
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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
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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.
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 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
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 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.
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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
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DEPARTMENT OF ECE JCET
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.
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Fig 5.1: Flow chart
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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.
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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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DEPARTMENT OF ECE JCET
.
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DEPARTMENT OF ECE JCET
35
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DEPARTMENT OF ECE JCET

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  • 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
  • 2. 2 SMART WALKING STICK DEPARTMENT OF ECE JCET 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.
  • 3. 3 SMART WALKING STICK DEPARTMENT OF ECE JCET 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.
  • 4. 4 SMART WALKING STICK DEPARTMENT OF ECE JCET 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
  • 5. 5 SMART WALKING STICK DEPARTMENT OF ECE JCET 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.
  • 6. 6 SMART WALKING STICK DEPARTMENT OF ECE JCET 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
  • 7. 7 SMART WALKING STICK DEPARTMENT OF ECE JCET 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
  • 8. 8 SMART WALKING STICK DEPARTMENT OF ECE JCET 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.
  • 9. 9 SMART WALKING STICK DEPARTMENT OF ECE JCET 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
  • 10. 10 SMART WALKING STICK DEPARTMENT OF ECE JCET 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.
  • 11. 11 SMART WALKING STICK DEPARTMENT OF ECE JCET 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
  • 12. 12 SMART WALKING STICK DEPARTMENT OF ECE JCET 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.
  • 13. 13 SMART WALKING STICK DEPARTMENT OF ECE JCET 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 XTAL2 18 XTAL1 19 ALE 30 EA 31 PSEN 29 RST 9 P0.0/AD0 39 P0.1/AD1 38 P0.2/AD2 37 P0.3/AD3 36 P0.4/AD4 35 P0.5/AD5 34 P0.6/AD6 33 P0.7/AD7 32 P1.0/T2 1 P1.1/T2EX 2 P1.2 3 P1.3 4 P1.4 5 P1.5 6 P1.6 7 P1.7 8 P3.0/RXD 10 P3.1/TXD 11 P3.2/INT0 12 P3.3/INT1 13 P3.4/T0 14 P3.7/RD 17 P3.6/WR 16 P3.5/T1 15 P2.7/A15 28 P2.0/A8 21 P2.1/A9 22 P2.2/A10 23 P2.3/A11 24 P2.4/A12 25 P2.5/A13 26 P2.6/A14 27 U1 AT89S52 C1 27p 11.0592 MHZ 27p X1 CRYSTAL R10 8.2k C3 10uf RESET TR1 TRAN-2P2S D1 DIODE D2 DIODE D3 DIODE D4 DIODE C4 1000u VI 1 VO 3 GND 2 U2 7809 230 v AC 12 v AC 9vDC D7 14 D6 13 D5 12 D4 11 D3 10 D2 9 D1 8 D0 7 E 6 RW 5 RS 4 VSS 1 VDD 2 VEE 3 LCD1 LM016L 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 1 VO 3 GND 2 U2 7805 BATTERY 5 V
  • 14. 14 SMART WALKING STICK DEPARTMENT OF ECE JCET 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.
  • 15. 15 SMART WALKING STICK DEPARTMENT OF ECE JCET 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
  • 16. 16 SMART WALKING STICK DEPARTMENT OF ECE JCET 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).
  • 17. 17 SMART WALKING STICK DEPARTMENT OF ECE JCET 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.,
  • 18. 18 SMART WALKING STICK DEPARTMENT OF ECE JCET 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
  • 19. 19 SMART WALKING STICK DEPARTMENT OF ECE JCET 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
  • 20. 20 SMART WALKING STICK DEPARTMENT OF ECE JCET 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.
  • 21. 21 SMART WALKING STICK DEPARTMENT OF ECE JCET 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
  • 22. 22 SMART WALKING STICK DEPARTMENT OF ECE JCET 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
  • 23. 23 SMART WALKING STICK DEPARTMENT OF ECE JCET 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
  • 24. 24 SMART WALKING STICK DEPARTMENT OF ECE JCET 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
  • 25. 25 SMART WALKING STICK DEPARTMENT OF ECE JCET 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.
  • 26. 26 SMART WALKING STICK DEPARTMENT OF ECE JCET  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
  • 27. 27 SMART WALKING STICK DEPARTMENT OF ECE JCET  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.
  • 28. 28 SMART WALKING STICK DEPARTMENT OF ECE JCET 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
  • 29. 29 SMART WALKING STICK DEPARTMENT OF ECE JCET 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.
  • 30. 30 SMART WALKING STICK DEPARTMENT OF ECE JCET Fig 5.1: Flow chart
  • 31. 31 SMART WALKING STICK DEPARTMENT OF ECE JCET 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.
  • 32. 32 SMART WALKING STICK DEPARTMENT OF ECE JCET 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.