TRR ENGINEERING COLLEGE A PROJECT REPORT ON “ROUTE GUIDANCE FOR BLIND PEOPLE USING GSM AND GPS MODEMS” Submitted in partial fulfillment of requirement for the award of degree of BACHELOR OF TECHNOLOGY IN ELECTRONICS AND COMMUNICATION ENGINEERING By CH. RAVI SANKAR (08D15A0408) A. KEERTHI PRIYA (07D11A0407) P. SUSHMA (07D11A0454) P. HIMAJA SREE (07D11A0497) DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING TRR ENGINEERING COLLEGE Page | 1 ROUTE GUIDENCE FOR THE BLIND
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TRR ENGINEERING COLLEGE
A PROJECT REPORT ON
“ROUTE GUIDANCE FOR BLIND PEOPLE USING GSM AND GPS MODEMS”
Submitted in partial fulfillment of requirement for the award of degree of
BACHELOR OF TECHNOLOGY
IN
ELECTRONICS AND COMMUNICATION ENGINEERING
By
CH. RAVI SANKAR (08D15A0408)
A. KEERTHI PRIYA (07D11A0407)
P. SUSHMA (07D11A0454)
P. HIMAJA SREE (07D11A0497)
DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING
TRR ENGINEERING COLLEGE
(AFFILIATED TO J.N.T.U HYDERABAD)
Inole (V) Patancheru (M) Medak (Dist)
HYDERABAD
2007 - 2011
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TRR ENGINEERING COLLEGE
TRR ENGINEERING COLLEGE
(AFFILIATED TO J.N.T.U HYDERABAD)
Inole (V) Patancheru (M) Medak (Dist)
HYDERABAD
DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING
CERTIFICATE
This is to certify that the project work entitled “ROUTE
GUIDANCE FOR BLIND PEOPLE USING GSM AND GPS
MODEMS” was being submitted by CH RAVI SANKAR
(08D15A0408), A KEERTHI PRIYA (07D11A0407), P SUSHMA
(07D11A0454) P HIMAJA SREE (07D11A0497). In partial fulfillment
of the requirement for the award of degree of bachelor of Technology in
Electronics and Communication Engineering from Jawaharlal Nehru
Technology University – Hyderabad. The results embodied in this project
have not been submitted to any other University or Institution of the
award of any Degree or Diploma.
Prof. C ASHOK KUMAR
Internal Supervisor & Head of the Department.
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YOUR PROJECT SURE – CERTIFICATE COMES IN
THIS PAGE
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ACKNOWLEDGEMENT
Our heartfelt thanks to our principal Prof. Dr. ANIL KUMAR for having
provided us the necessary infrastructure required for the successful completion of our
project.
We acknowledge our gratitude to Prof. C. ASHOK KUMAR, Head of the
Department, Electronics and Communication Engineering, for the constant guidance
and encouragement.
We thank our internal guide Prof. C. ASHOK KUMAR, for his help and
invigorating suggestions extended with immense care throughout our work.
Our sincere thanks to all of the teaching and non – teaching staff for extending
their support and cooperation for the completion of our project.
CH. RAVI SANKAR (08D15A0408)
A. KEERTHI (07D11A0407)
P. HIMAJA SREE (07D11A0497)
P. SUSHMA (07D11A0454)
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CONTENTS
ABSTRACT
List of figures
List of tables
CHAPTER – I
1.1 INTRODUCTION 1
1.2 HISTORY 1
1.3 MOTIVATION 2
1.4 OBJECTIVE 3
1.5 DESIGN POSSIBILITIES 3
1.6 ORGANISATION OF DOCUMENT 4
1.7 BLOCK DIAGRAM 5
CHAPTER – II: MAJOR COMPONENTS 6
2.1 HARDWARE PARTS
2.1.1 MICROCONTROLLER 7
2.1.2 GPS 13
2.1.3 GSM 26
2.1.4 LCD 36
2.1.5 MAX232 41
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2.1.6 BUFFER IC (74LS244) 44
2.1.7 POWER SUPPLY 47
2.1.8 INPUT KEYPADS 55
2.1.9BUZZER 56
2.1.10 SERIAL COMMUNICATION (RS 232) 56
2.1.11UART 58
CHAPTER – III:
3.1 CIRCUIT DIAGRAM 68
3.2 INITIAL CIRCUITARY 70
3.3 FINAL CIRCUITARY 71
CHAPTER 4: ADDITIONAL FEATURES:
4.1 INTRODUCTION 72
4.2 COMPONENTS UTILIZED 72
4.2.1 TWO 7555 TIMERIC’S 72
4.2.2 PHOTODIODE 74
4.2.3 INFRARED LED 75
4.2.4 TRANSISTOR BC54 77
CHAPTER – V
CODING
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CHAPTER – VI
6.1 ADVANTAGES 79
6.2 LIMITATIONS OF EXISTING DEVICES 79
6.3 APPLICATIONS 80
6.4 FUTURE SCOPE 80
6.5 ACTUAL WAY OF ACCESING THE MODEL 81
CHAPTER – VII
RESULT 82
CONCLUSION 83
REFERENCES 84
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ABSTRACT
Based on the investigation about daily activity characteristics and modes
of the blind, the study found that the main difficulties encountered in a trip
of the blind included walking on the road, finding way, taking a bus and
looking for usual life - arena. After analyzing the research and application of
actual blind navigation technologies, to solve the demands and difficulties in
the blind trip, the study presents a blind navigation system based on Radio
Frequency Identification through wireless and mobile communications
technologies. The system consists of GPS, GSM which can be integrated into
the blind cane, mobile phone, Call Center and center information servers. Using
this system, the blind are able to know their location, condition of roads,
vicinity buildings, and inquire about the optimal routes to their destination and
available vehicles. The technologies used in this navigation system are mature,
which ensures the system is practical, universal and with perfect function.
One of the major goals for blind and visually impaired people is independent
mobility. In this paper an electronic travel aid for blind pedestrians is then described.
It involves a sensor in the integrated cane to detect the movement of the user when he
walks and a microcontroller with synthetic speech output. This aid is a portable, self
contained system that will allow blind and visually impaired individuals to travel
through familiar and unfamiliar environments without the assistance of guides. In
addition, it provides information to the user about urban walking routes using spoken
words to indicate what decisions to make.
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LIST OF FIGURES:
1. GLOBALLY BLIND PEOPLE HISTORY
2. TELECOMMUNICATION NETWORK
3. SPACE SEGMENT
4. SYSTEM SEGMENTATION
5. A GPS SATELLITE
6. USER SEGMENT
7. NAVIGATIONAL SIGNALS
8. THREE DIMENSIONAL COORDINATE SYSTEM
9. GPS APPLICATIONS IN CIVILIAN
10. GSM NETWORK
11. GSM NETWORK AREAS
12.PIN DIAGRAM OF 16*1 LCD LINES
13. MAX 232 IC
14. CIRCUIT CONNECTIONS OF MAX232
15.CONNECTION DIAGRAM OF BUFFER IC
16. CIRCUIT DIAGRAM FOR POWER SUPPLY
17. IDEAL STEP DOWN TRANSFORMER SHOWING MAGNETIC FLUX IN
THE CORE
18. IDEAL TRANSFORMER
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19. BRIDGE RECTIFIER CIRCUIT
20. AC HALF WAVE, FULLWAVE RECTIFIED SIGNALS
21. DIODE BRIDGE SMOOTHING
22. DB9 PIN DIAGRAM
23. UART PIN DIAGRAMS
24. PHOTODIODE MODEL
25. IR LED OPERATION DIAGRAM
26. IR LED MODEL
27. TRANSISTOR BC547 & ITS SYMBOL REPRESENTATION
LIST OF TABLES:
1 TCON REGISTES
2. TMOD REGISTERS
3. ADDRESS LOCATIONS OF16*1 LCD LINES
4. FUNCTION TABLE
5. RECOMMENDED OPERATING CONDITIONS
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CHAPTER – I
1.1 INTRODUCTION
People who are blind or visually impaired have choices when it comes to
travelling. At any given time, they can travel using a human guide, holding onto
someone's arm; use a long, white cane to identify and avoid obstacles; use a dog
guide, use special optical or electronic aids, or use no additional aid. The choice of
tools depends on the extent and nature of visual impairment, personal preference,
lighting, and familiarity with the area. In order to travel independently, people with
visual impairments use whatever vision they have, auditory and tactual clues, and
other information they know about an area to keep track of their locations and make
travel decisions.
In this paper, the proposed electronic travel aid involves a
microcontroller with speech output. It is a self contained portable
electronic unit. It can supply the blind person with assistance about
walking routes by using a speech synthesizer to point out what
decisions to make. In addition, the software permits a blind person
to explore the electronic map as well as planning the optimum route
to the desired destination.
1.2 HISTORY:
Simple Electronic Travel Aids have been in development since 1897[BRA,
85]. Real and more complex developments occurred after the Second World War and
through the 1950s and 60s [HEY, 83]. With the advent of the possibilities of remote
sensing in the form of ultrasound and radar more research effort was directed at the
problems of remote sensing of the environment for visually impaired people.
Advances in electronics and circuit miniaturization also aided the development of
these devices into portable mobility machines and a number of devices using these
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technologies were developed such as the ‘Mowat Sensor’ [KAY, 84], and the ‘Sona’
[KEL, 84].
Through the 1960s and 70s obstacle detection devices continued to be
developed using a variety of sensing methods, notably lasers. However advances in
the pre-planning of routes were also taking place and with the advent of ‘capsule
paper’ (which expands when heated) tactile maps could be produced more easily than
previously existing methods. Later in the 1980s and 1990s further research allowed a
form of tactile map [JAC, 94] that talked to be developed. Recently through the early
1990s the focus has switched from mobility and obstacle detection to orientation and
location [KAW, 00]-[LOO, 98]. These systems, called ‘Audible Signs’[BEN, 95],
‘Sound Buoys’[BLE, 97] etc, transmit some form of remote signal once a user gets
into range of the device, which then delivers an audible message, either as a tone or
speech. While these systems do solve some problems and despite being relatively
inexpensive, it can be expensive to place these signs extensively in an environment.
FIG 1.1: GLOBALLY BLIND PEOPE IN EARTH
1.3 MOTIVATION:
Imagine walking into an unfamiliar airport. The places we have to search for,
airline ticket counter, security check-in, boarding gate, are difficult to and even with
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signs. Imagine how much of a challenge this would be if you cannot even see the
signs!
Many medical and academic buildings lack even this kind of navigation
assistance. Challenging for a sighted person, the task of ending a way in such a
building for an unassisted person with visual impairment becomes nearly impossible.
Outdoor mobility can present more potential dangers to blind travelers
because obstacles and Hazards such as motor vehicles and dangerous terrain can be
life-threatening.
Navigation tends to be more difficult indoors because the environment is so
homogeneous. Rather than searching for unique features, a traveler needs to count
doorways and intersections or find some other way to distinguish between largely
identical features such as offices or doorways.
Thus the implementation of this design helps motivates the visually impaired
feel independent and confident in their lives and also brings up their spirit in
succeeding in every field possible without making their visually impairedness as their
major contempt in life and this design helps people find out the route anywhere in the
world in the most easiest way.
1.4 OBJECTIVE:
The main goal of the project is to provide cost - effective way to
allow buildings to support blind people.
Audio route announcement for the blind hopes to allow visually
impaired users to simply press a button, speak the desired
destination, and be guided there with the use of the audio
instructions.
The system hopes to provide a portable unit that can be easily
carried and operated by visually impaired user. It could be easily
incorporated into walking cane.
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1.5 DESIGN POSSIBILITIES:
Many different design possibilities were explored during research.
Wireless Sensor Networks – Due to the high amount of sensors required for
large buildings, this may be impractical, especially when user direction must
be tracked. Programming would be much more complex.
RSSI Techniques – This can be effective at finding distances base on signal
strength but is also affected by the direction problem.
RFID – Seems to provide the most cost effective and simplest way to
determine direction using the technique that the team has developed. The
programming using this technique would also be less complex
1.6 ORGANISATION OF DOCUMENTATION:
In this project documentation we have initially put the
definition and objective of the project as well as the design of the
project which is followed by the implementation and coding phase.
Finally the project has been concluded successfully and also the
future enhancements of the project were given in this
documentation
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1.7 BLOCK DIAGRAM:
TEXT
FORMAT
IN THE FORM OF TEXT
AUTOMATIC CALL
FORWARDING
AUDIO FORMAT
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GPS
MODULE
GSM
MODULE
KEYPAD CONSISTING OF SWITCHES
89S52
MICRO-
CONTROLLER
MOBILE PHONE
OF BLIND PERSON
LCD
(LIQUID CRYSTAL DISPAY)
SERVICE CENTRE
TRR ENGINEERING COLLEGE
OUTPUT
FIGURE 1.2: BLOCK DIAGRAM
CHAPTER – II
MAJOR COMPONENTS
2.1 MICROCONTROLLER:
A) DESCRIPTION OF MICROCONTROLLER 89S52:
The AT89S52 is a low-power, high-performance CMOS 8-bit micro
controller with 8Kbytes of in-system programmable Flash memory. The device is
manufactured Using Atmel’s high-density nonvolatile memory technology and is
compatible with the industry-standard 80C51 micro controller. The on-chip Flash
allows the program memory to be reprogrammed in-system or by a conventional
nonvolatile memory programmer.
By combining a versatile 8-bit CPU with in-system programmable flash
one monolithic chip; the Atmel AT89S52 is a powerful micro controller, which
provides a highly flexible and cost-effective solution to many embedded control
applications.
B) FEATURES OF AT89S52:
Compatible with MCS-51 Products
8K Bytes of In-System Programmable (ISP) Flash Memory
Endurance: 1000 Write/Erase Cycles
4.0V to 5.5V Operating Range
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Fully Static Operation: 0 Hz to 33 MHz
Three-level Program Memory Lock
256K Internal RAM
32 Programmable I/O Lines
3 16-bit Timer/Counters
Eight Interrupt Sources
Full Duplex UART Serial Channel
Low-power Idle and Power-down Modes
Interrupt Recovery from Power-down Mode
Watchdog Timer
Dual Data Pointer
Power of flag
C) PIN CONFIGURATION
FIGURE 2.1: PIN CONFIGURATION OF AT89S52
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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, full duplex serial port, on-chip oscillator, and clock
circuitry. In addition, the AT89S52 is designed with static logic for penetration
down to zero frequency and supports two software selectable power saving
modes. The Idle Mode stops the CPU while allowing the RAM timer/counters,
serial port, and interrupt system to continue functioning. The Power-down mode
saves the RAM contents but freezes the oscillator, disabling all other chip
functions until the next interrupt or hardware reset.
D) SPECIAL FUNCTION REGISTER (SFR) MEMORY:
Special Function Registers (SFR s) are areas of memory that control specific
functionality of the 8051 processor. For example, four SFRs permit access to the
8051’s 32 input/output lines. Another SFR allows the user to set the serial baud
rate, control and access timers, and configure the 8051’s interrupt system.
E) THE ACCUMULATOR:
The Accumulator, as its name suggests is used as a general register to accumulate
the results of a large number of instructions. It can hold 8-bit (1-byte) value and
is the most versatile register.
F) THE “R” REGISTERS:
The “R” registers are a set of eight registers that are named R0, R1etc up to R7.
These registers are used as auxiliary registers in many operations.
The “B” registers: The “B” register is very similar to the accumulator in the
sense that it may hold an 8-bit (1-byte) value. Two only uses the “B” register
8051 instructions: MUL AB and DIV AB.
The Data Pointer: The Data pointer (DPTR) is the 8051’s only user
accessible 16-bit (2Bytes) register. The accumulator, “R” registers are all 1-Byte
values. DPTR, as the name suggests, is used to point to data. It is used by a
number of commands, which allow the 8051 to access external memory.
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G) THE PROGRAM COUNTER AND STACK POINTER:
The program counter (PC) is a 2-byte address, which tells the 8051 where the next
instruction to execute is found in memory. The stack pointer like all registers except
DPTR and PC may hold an 8-bit (1Byte)value.
H) TYPES OF MEMORY:
The 8051/8052 has three very general types of memory. To effectively program the
8051/8052 it is necessary to have a basic understanding of these memory types.
The memory types are illustrated in the following graphic. They are: On-Chip
Memory, External Code Memory, and External RAM.
On-Chip Memory refers to any memory (Code, RAM, or other) that physically exists
on the microcontroller itself. On-chip memory can be of several types, but we'll get
into that shortly.
External Code Memory is code (or program) memory that resides off-chip. This is
often in the form of an external EPROM.
External RAM is RAM memory that resides off-chip. This is often in the form of
standard static RAM or flash RAM.
I) TCON REGISTER:
TABLE 2.1: TIMER/COUNTER CONTROL REGISTER
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J) TMOD REGISTER:
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TABLE 2.2: TIMER/COUNTER 0 AND 1 MODES
2.1.2 GLOBAL POSITIONING SYSTEMPage | 21
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a) INTRODUCTION:
The Global Positioning System (GPS) is the only fully functional Global
Navigation Satellite System (GNSS). The GPS uses a constellation of between 24 and
32 Medium Earth Orbit satellites that transmit precise microwave signals, which
enable GPS receivers to determine their location, speed,. GPS was developed by the
United States Department of Defense. Its official name is NAVSTAR-GPS.
Although NAVSTAR-GPS is not an acronym, a few acronyms have been created for
it. The GPS satellite constellation is managed by the United States Air Force 50th
Space Wing.
Global Positioning System is an earth-orbiting-satellite based system that
provides signals available anywhere on or above the earth, twenty-four hours a day,
which can be used to determine precise time and the position of a GPS receiver in
three dimensions. GPS is increasingly used as an input for Geographic Information
Systems particularly for precise positioning of geospatial data and the collection of
data in the field. Precise positioning is possible using GPS receivers at reference
locations providing corrections and relative positioning data for remote receivers.
Time and frequency dissemination, based on the precise clocks on board the
SVs and controlled by the monitor stations, is another, use for GPS. Astronomical
observatories telecommunications facilities and laboratory standards can be set to
precise time signals or controlled to accurate frequencies by special purpose GPS
receivers.
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FIGURE 2.1 GPS SETELLITE VIEW
FIGURE 2.2 GPS LONGITUDE & LATTITUDE INDICATOR
b) BASIC CONCEPT OF GPS OPERATION:
A GPS receiver calculates its position by carefully timing the signals sent by
the constellation of GPS satellites high above the Earth. Each satellite continually Page | 23
The function of this capacitor, known as a reservoir capacitor (aka smoothing
capacitor) is to lessen the variation in (or 'smooth') the rectified AC output voltage
waveform from the bridge. One explanation of 'smoothing' is that the capacitor
provides a low impedance path to the AC component of the output, reducing the AC
voltage across, and AC current through, the resistive load. In less technical terms, any
drop in the output voltage and current of the bridge tends to be cancelled by loss of
charge in the capacitor.
This charge flows out as additional current through the load. Thus the change of load
current and voltage is reduced relative to what would occur without the capacitor.
Increases of voltage correspondingly store excess charge in the capacitor, thus
moderating the change in output voltage / current. Also see rectifier output
smoothing.
The capacitor and the load resistance have a typical time constant τ = RC where C and
R are the capacitance and load resistance respectively. As long as the load resistor is
large enough so that this time constant is much longer than the time of one ripple
cycle, the above configuration will produce a smoothed DC voltage across the load.
In some designs, a series resistor at the load side of the capacitor is added. The
smoothing can then be improved by adding additional stages of capacitor–resistor
pairs, often done only for sub-supplies to critical high-gain circuits that tend to be
sensitive to supply voltage noise.
f) VOLTAGE REGULATOR:
A voltage regulator is an electrical regulator designed to automatically maintain a
constant voltage level.
The 78xx (also sometimes known as LM78xx) series of devices is a family of self-
contained fixed linear voltage regulator integrated circuits. The 78xx family is a very
popular choice for many electronic circuits which require a regulated power supply,
due to their ease of use and relative cheapness. When specifying individual ICs within
this family, the xx is replaced with a two-digit number, which indicates the output
voltage the particular device is designed to provide (for example, the 7805 has a 5
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volt output, while the 7812 produces 12 volts). The 78xx line is positive voltage
regulators, meaning that they are designed to produce a voltage that is positive
relative to a common ground. There is a related line of 79xx devices which are
complementary negative voltage regulators. 78xx and 79xx ICs can be used in
combination to provide both positive and negative supply voltages in the same circuit,
if necessary.
2.1.8 INPUT KEYPADS:
The inputs ie.4 inputs are utilized here with their specific destinations where the blind
person frequently visits, and these keypads are connected to the port 2 of
microcontroller that is to pin 2122,23,24 to transmit this particular data of the
location of the blind person’s i.e. latitude and longitude and his destination number.
This information reaches the buffer of the microcontroller and thus the remaining
process continues.
So initial inputs are very important for this project and it plays a major and crucial
role in this project by passing on the basic information for tracking of the route
through GPS and sending that tracked information to the service centre through GSM
and thus helps the blind person’s accessibility to go around in a much comfortable
and allow him to live independently.
2.1.9 BUZZER:
Buzzer is one of the component which is connected to the microcontroller of port 2
and pin 25.It has an audible range of 50 DB and thus it helps the blind person to know
that the tracked information is sent through the microcontroller to the GSM to the
customer service and thus it also has an important role . This is the buzzer that gives
the information about the message that reached LCD.
There is another buzzer near the GSM for the ring of the phone that is connected to
the DTMF socket, but here this buzzer in our project has an audible range of 10-15 db
and this can be extended by soldering the pin behind it in the GSM module and thus
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can be used in real time implementation which produces double the sound it produced
initially.
Thus buzzer is one of the important component for the blind person to act
accordingly and lead an independent life in a better way.
2.1.10 SERIAL COMMUNICATION (RS232):
The serial communication is the most important component in this project as it
helps in communication between microcontroller, gps and gsm .An RS232 serial
communication is used for most of the projects as it is the only serial, asynchronous
form of communication. The following RS232 connectors can be used to test a
serial port on your computer. The data and handshake lines have been linked. In this
way all data will be sent back immediately. The PC controls its own handshaking.
The first test plug can be used to check the function of the RS232 serial port with
standard terminal software. The second version can be used to test the full
functionality of the RS232 serial port with Norton Diagnostics or Check it.
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FIGURE 2.22 SERIAL COMMUNICATION PORTS
A) ADVANTAGES OF SERIAL OVER PARLLEL COMMUNICATION:
Serial Cables can be longer than Parallel cables. The serial port transmits a '1' as -3 to -25 volts and a '0' as +3 to +25 volts where as a parallel port transmits a '0' as 0v and a '1' as 5v. Therefore the serial port can have a maximum swing of 50V compared to the parallel port which has a maximum swing of 5 Volts. Therefore cable loss is not going to be as much of a problem for serial cables than they are for parallel.
You don't need as many wires than parallel transmission. If your device needs to be mounted a far distance away from the computer then 3 core cable (Null
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Modem Configuration) is going to be a lot cheaper that running 19 or 25 core cable. However you must take into account the cost of the interfacing at each end.
Infra Red devices have proven quite popular recently. You may of seen many electronic diaries and palmtop computers which have infra red capabilities build in. However could you imagine transmitting 8 bits of data at the one time across the room and being able to (from the devices point of view) decipher which bits are which? Therefore serial transmission is used where one bit is sent at a time. IrDA-1 (The first infra red specifications) was capable of 115.2k baud and was interfaced into a UART. The pulse length however was cut down to 3/16th of a RS232 bit length to conserve power considering these devices are mainly used on diaries, laptops and palmtops.
Microcontroller's have also proven to be quite popular recently. Many of these have in built SCI (Serial Communications Interfaces) which can be used to talk to the outside world. Serial Communication reduces the pin count of these MPU's. Only two pins are commonly used, Transmit Data (TXD) and Receive Data (RXD) compared with at least 8 pins if you use a 8 bit Parallel method (You may also require a Strobe).
2.1.11 UART:
UART stands for Universal Asynchronous Receiver / Transmitter. Its the little box of tricks found on your serial card which plays the little games with your modem or other connected devices. Most cards will have the UART's integrated into other chips which may also control your parallel port, games port, floppy or hard disk drives and are typically surface mount devices. The 8250 series, which includes the 16450, 16550, 16650, & 16750 UARTS are the most commonly found type in your PC. Later we will look at other types which can be used in your homemade devices and projects.
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FIGURE 2.24 UART PIN CONFIGURATION
The 16550 is chip compatible with the 8250 & 16450. The only two differences are pins 24 & 29. On the 8250 Pin 24 was chip select out which functioned only as a indicator to if the chip was active or not. Pin 29 was not connected on the 8250/16450 UARTs. The 16550 introduced two new pins in their place. These are Transmit Ready and Receive Ready which can be implemented with DMA (Direct Memory Access). These Pins have two different modes of operation. Mode 0 supports single transfer DMA where as Mode 1 supports Multi-transfer DMA.
All the UARTs pins are TTL compatible. That includes TD, RD, RI, DCD, DSR, CTS, DTR and RTS which all interface into your serial plug, typically a D-type connector. Therefore RS232 Level Converters (which we talk about in detail later) are used.
These are commonly the DS1489 Receiver and the DS1488 as the PC has +12 and -12 volt rails which can be used by these devices. The RS232 Converters will convert the TTL signal into RS232 Logic Levels.
The UART requires a Clock to run. If you look at your serial card a common
crystal found is either a 1.8432 MHZ or a 18.432 MHZ Crystal. The crystal in
connected to the XIN-XOUT pins of the UART using a few extra components which
help the crystal to start oscillating. This clock will be used for the Programmable
Baud Rate Generator which directly interfaces into the transmit timing circuits but not
directly into the receiver timing circuits. For this an external connection mast be made
from pin 15 (Baud Out) to pin 9 (Receiver clock in.) Note that the clock signal will be
at Baud rate * 16
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CHAPTER - III
3.1 CIRCUIT DIAGRAM:
FIGURE 3.1 CIRCUIT DIAGRAM OF ROUTE GUIDANCE ANNOUNCER
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3.2 INITIAL CIRCUITARY
FIGURE 3.2 INITIAL CIRCUIT OE ROUTE GUIDANCE
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3.3 FINAL CIRCUITARY
FIGURE 3.3 FINIAL CIRCUIT OE ROUTE GUIDANCE
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CHAPTER – IV
ADDITIONAL FEATURES:
4.1 INTRODUCTION:
One of the major goals for blind and visually impaired people is independent
mobility. In this paper we have an additional feature that if used creates most comfort
for the visually blind person. It involves a sensor in the integrated cane to detect the
movement of the user when he walks. This aid is a portable, self contained system
that will allow blind or visually impaired individuals to travel through familiar and
unfamiliar environments without the assistance of guide i.e. through the customer
service. In addition, it provides information to the user about urban walking routes
using spoken words to indicate what decisions to make and helps him from easily
knowing the hurdles.
4.2 COMPONENTS UTILIZED:
4.2.1 TWO 7555 TIMERIC’S
4.2.2 PHOTODIODE
4.2.3 INFRARED LED
4.2.4 TRANSISTOR BC547
4.2.1 7555 TIMER IC’S:
The ICM7555 is a CMOS timer providing significantly improved performance over
the standard NE/SE555 timer, while at the same time being a direct replacement for
those devices in most applications. Improved parameters include low supply current,
wide operating supply voltage range, low THRESHOLD, TRIGGER, and RESET
currents, no crow barring of the supply current during output transitions, higher
frequency performance and no requirement to decouple CONTROL_VOLTAGE for
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The ICM7555 is a stable controller capable of producing accurate time delays or
Frequencies.
In the one-shot mode, the pulse width of each circuit is precisely controlled by one
external resistor and capacitor. For a stable operation as an oscillator, the free-running
frequency and the duty cycle are both accurately controlled by two external resistors
and one capacitor.
1. FEATURES:
Exact equivalent in most applications for NE/SE555
Low supply current: 80 mA (typical)
Extremely low trigger, threshold, and reset currents: 20 pA (typical)
High-speed operation: 500 kHz guaranteed
Wide operating supply voltage range guaranteed 3 V to 16 V over full
automotive
Temperatures
Normal reset function; no crow barring of supply during output transition
Can be used with higher-impedance timing elements than the NE/SE555 for
longer
Time constants.
APPLICATIONS:
Precision timing
Pulse generation
Sequential timing
Time delay generation
Pulse width modulation
Pulse position modulation
Missing pulse detector
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4.2.2 PHOTODIODE:
PHOTODIODE:
A photodiode is a type of photo detector capable of converting light into either current or voltage, depending upon the mode of operation.
QSD2030F — Plastic Silicon Photodiode
FIGURE 4.1: GENERAL PHOTO DIODE
1) PRINCIPLE OF OPERATION:
A photodiode is a PN junction or PIN structure. When a photon of sufficient energy strikes the diode, it excites an electron, thereby creating a free electron and a (positively charged electron hole). This mechanism is also known as the photoelectric effect. If the absorption occurs in the junction's depletion region, or one diffusion length away from it, these carriers are swept from the junction by the built-in field of the depletion region. Thus holes move toward the anode, and electrons toward the cathode, and a photocurrent is produced.
FEATURES:
Critical performance parameters of a photodiode include:
Responsivety:
The ratio of generated photocurrent to incident light power, typically expressed in A/W when used in photoconductive mode. The Responsivety may also be expressed as a Quantum efficiency, or the ratio of the number of photo generated carriers to incident photons and thus a unites quantity.
Dark current:
The current through the photodiode in the absence of light, when it is operated in photoconductive mode. The dark current includes photocurrent generated by background radiation and the saturation current of the semiconductor junction. Dark
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current must be accounted for by calibration if a photodiode is used to make an accurate optical power measurement, and it is also a source of noise when a photodiode is used in an optical communication system.
Noise-equivalent power:
(NEP) The minimum input optical power to generate photocurrent, equal to the rms noise current in a 1 hertz bandwidth. The related characteristic directivity (D) is the
inverse of NEP, 1/NEP; and the specific directivity ( ) is the detectives normalized
to the area (A) of the photo detector, . The NEP is roughly the minimum detectable input power of a photodiode.
When a photodiode is used in an optical communication system, these parameters contribute to the sensitivity of the optical receiver, which is the minimum input power required for the receiver to achieve a specified bit error ratio.
Applications
P-N photodiodes are used in similar applications to other photodetectors such as photoconductors, charge-coupled devices, and photomultiplier tubes.
Photodiodes are used in consumer electronics devices such as compact disc players, smoke detectors, and the receivers for remote controls in VCRs and televisions.
In other consumer items such as camera light meters, clock radios (the ones that dim the display when it's dark) and street lights, photoconductors are often used rather than photodiodes, although in principle either could be used.
Photodiodes are often used for accurate measurement of light intensity in science and industry. They generally have a better, more linear response than photoconductors.
They are also widely used in various medical applications, such as detectors for computed tomography (coupled with scintillations) or instruments to analyze samples (immunoassay). They are also used in pulse ox meters.
4.2.3 INFRARED LED
1) GENERAL DESCRIPTION:
It is the same principle in ALL Infra-Red proximity sensors. The basic idea is to send infra red light through IR-LEDs, which is then reflected by any object in front of the sensor.
Then all you have to do is to pick-up the reflected IR light. For detecting the reflected IR light, we are going to use a very original technique: we are going to use another IR-LED, to detect the IR light that was emitted from another led of the exact same type!
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FIGURE 4.2: OPRATION OF IR LED
2) PRINCIPLE OF OPERATION:
This is an electrical property of Light Emitting Diodes (LEDs) which is the fact that a led Produce a voltage difference across its leads when it is subjected to light. As if it was a photo-cell, but with much lower output current. In other words, the voltage generated by the leds can't be - in any way - used to generate electrical power from light, It can barely be detected. that's why as you will notice in the
schematic, we are going to use a Op-Amp (operational Amplifier) to accurately detect very small voltage changes.
FIGURE 4.3 GENERAL IR LED
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FEATURES
• = 940 nm
• Chip material =GaAs with AlGaAs window
• Package type: T-1 3/4 (5mm lens diameter
• Matched Photo sensor: QSD122/123/124
• Medium Emission Angle, 40°
• High Output Power
•Package material and color: Clear, united, plastic
• Ideal for remote control application
4.2.4 TRANSISTOR BC547:
1) DESCRIPTION
The BC547 transistor is an NPN Epitaxial Silicon Transistor. The BC547 transistor is a general-purpose transistor in a small plastic package. It is used in general-purpose switching and amplification BC847/BC547 series 45 V, 100 mA NPN general-purpose transistors.
The BC547 transistor is an NPN bipolar transistor, in which the letters "N" and "P" refer to the majority charge carriers inside the different regions of the transistor. Most bipolar transistors used today are NPN, because electron mobility is higher than hole mobility in semiconductors, allowing greater currents and faster operation. NPN transistors consist of a layer of P-doped semiconductor (the "base") between two N-doped layers. A small current entering the base in common-emitter mode is amplified in the collector output. In other terms, an NPN transistor is "on" when its base is pulled high relative to the emitter. The arrow in the NPN transistor symbol is on the emitter leg and points in the direction of the conventional current flow when the device is in forward active mode. One mnemonic device for identifying the symbol for the NPN transistor is "not pointing in." An NPN transistor can be considered as two diodes with a shared anode region. In typical operation, the emitter base junction is forward biased and the base collector junction is reverse biased.
In an NPN transistor, for example, when a positive voltage is applied to the base emitter junction, the equilibrium between thermally generated carriers and the repelling electric field of the depletion region becomes unbalanced, allowing thermally excited electrons to inject into the base region. These electrons wander (or "diffuse") through the base from the region of high concentration near the emitter towards the region of low concentration near the collector. The electrons in the base are called minority carriers because the base is doped p-type which would make holes the majority carrier in the base
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FIGURE 4.4 BC547 TRANSISTOR
1) BC547 Transistor Circuit Schematic Symbol
2) FEATURES:
• Low current
• Low voltage
• Three different gain selections
3) APPLICATIONS:
General-purpose switching and amplification
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CHAPTER – V
CODING
SOFTWARE USED: “EMBEDDED C”
/*******************/
#include<reg51.h>
#include"lcddisplay.h"
#include"UART.h"
#include<string.h>
#include<intrins.h>
sbit buzzer = P1^7;
sbit gsm = P3^3;
sbit gps = P3^2;
sbit sw1 = P1^0;
sbit sw2 = P1^1;
sbit sw3 = P1^2;
sbit sw4 = P1^3;
unsigned char mobilenum[]="9908172936";
unsigned char msg[5];
unsigned char XX,newmsg=0,a,dest=0,temp[5],jj=0;
/** interrupt function to receive the data from GSM *****/
void serintr(void) interrupt 4
{
if(RI==1)
{
XX=SBUF;
if(XX=='+')
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newmsg=1;
else
{
temp[jj++]=XX;
}
if(jj==10)
jj=0;
RI=0;
}
}
void main()
{
unsigned char i,gpsdata[45];
lcd_init();
UART_init();
lcdcmd(0x85);
sw1=sw2=sw3=sw4=1;
gps=1;
gsm=0;
RI=0;
lcdcmd(0x01);
msgdisplay ("searching for");
lcdcmd(0xc0);
msgdisplay("GSM modem");
delay(300);
send_to_modem("ate0"); //to avoid echo signals,
enter();
again:
send_to_modem("at"); // TO CHECKING GSM MODEM...
enter();
if(!RI) // Here we are waiting for data
witch is sending by GSM modem
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goto again;
RI=0;
EA=1;
ES=1;
lcdcmd(0x01);
msgdisplay("SYSTEM");
cdcmd(0xc3);
msgdisplay("CONNECTED");
delay(100);
send_to_modem("at+creg=0"); //
enter();
delay(300);
newmsg=0;
xxx: lcdcmd(0x01);
msgdisplay("CHEKING SIM");
send_to_modem("AT+CPIN?"); //
enter();
delay(500);
if(newmsg==0)
goto xxx;
lcdcmd(0xC0);
msgdisplay ("SIM CONNECTED");
delay(500);
send_to_modem("at+cmgf=1"); // tr set message
format as text
mode
enter();
st:
lcdcmd(0x01);
msgdisplay("route guiding");
lcdcmd(0xC0);
msgdisplay("SYSTEM");
delay(500);
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newmsg=0;
TR1=0;
TH1=-6;
gsm=1; // deselect the gsm
gps=0; // select the gps
TR1=1;
RI=0;
jj=0 ;
delay(100);
while(1)
{
RI=0;
a=0;
while(a!='$') //wait till the data
started from gps
{
while(RI==0);
a=SBUF;
RI=0;
}
i=0;
while(RI==0);
i=i+1;
RI=0;
while(RI==0);
RI=0;
i=i+1;
while(RI==0);
if(SBUF=='R') // take the value from gprmc command