1 CHAPTER 1 INTRODUCTION 1.1 OVERVIEW There are lots of efforts being made by public transport corporations to improve public vehicle occupancy by requesting the public to use public transport over other modes of transportation. It can be noted that if the passenger knows with high confidence that the bus is going to come, he/she will definitely wait rather than opting for other modes of transportation. Efficient information can therefore help the users to choose faster and easier connections, which saves their time. Trends in wireless technology like Global System for Mobile communication (GSM) and RF Technology have resulted in easier and faster communication. Thus, this Project provides a very cost-effective solution as compared to existing technologies for tracking public vehicles. 1.2 BACKGROUND One of the possible reasons for people preferring private vehicles to public vehicles are that a passenger normally does not have exact information about the public vehicle arrival timing at their stops. By providing reliable public vehicle arrival information to the passengers at predefined stops, public vehicle occupancy can be improved. This is beneficial to both the passengers and public transport corporations. Tracking of a vehicle can be expressed as continuously monitoring of a vehicle. Tracking of buses can be useful for the automation of existing transportation systems. By the use of tracking the information about bus-arrival timing can be easily provided to passengers.
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1
CHAPTER 1
INTRODUCTION
1.1 OVERVIEW
There are lots of efforts being made by public transport corporations to
improve public vehicle occupancy by requesting the public to use public
transport over other modes of transportation. It can be noted that if the
passenger knows with high confidence that the bus is going to come, he/she
will definitely wait rather than opting for other modes of transportation.
Efficient information can therefore help the users to choose faster and easier
connections, which saves their time. Trends in wireless technology like
Global System for Mobile communication (GSM) and RF Technology have
resulted in easier and faster communication. Thus, this Project provides a
very cost-effective solution as compared to existing technologies for
tracking public vehicles.
1.2 BACKGROUND
One of the possible reasons for people preferring private vehicles to public
vehicles are that a passenger normally does not have exact information about
the public vehicle arrival timing at their stops. By providing reliable public
vehicle arrival information to the passengers at predefined stops, public
vehicle occupancy can be improved. This is beneficial to both the passengers
and public transport corporations. Tracking of a vehicle can be expressed as
continuously monitoring of a vehicle. Tracking of buses can be useful for the
automation of existing transportation systems. By the use of tracking the
information about bus-arrival timing can be easily provided to passengers.
2
The different wireless technologies available today have resulted in the
reliable and faster communication. GSM is an open, digital cellular
technology used for transmitting mobile voice and data services. GSM has
become the world’s fastest growing mobile communication standard. GSM
networks operate in a number of different carrier frequency ranges
(separated into GSM frequency ranges for 2G and UMTS frequency bands
for 3G), with most 2G GSM networks operating in the 900 MHz or 1800
MHz bands. The GSM network is structured into a number of discrete
sections:
(i) The Base Station Subsystem (the base stations and their controllers).
(ii) The Network and Switching Subsystem (the part of the network most
similar to a fixed network). This is sometimes also just called the core
network.
(iii) The GPRS Core Network (the optional part that allows packet based
Internet connections).
(iv) Operation Support System (OSS) for maintenance of the network.
Radio-Frequency Transceiver is a wireless sensor technology, which is
based on the detection of electromagnetic signals. There is emission of radio
waves from the transmitter, which can reach up to 100 feet or more,
depending on its power output and the radio frequency used.
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CHAPTER 2
DESIGN AND DESCRIPTION
2.1 BLOCK DIAGRAM
Fig 2.1 Block Diagram
BUS
RF RECEIVER
+ CONTROLLER
+ GSM MODEM
+ LCD DISPLAY
GSMNETWORK
RF TRANSMITTER
BUSSTOP2BUSSTOP3
BUSSTOP
BUSSTOP1
4
2.2 BASIC DESCRIPTION
The basic block diagram of the bidirectional visitor counter with automatic
light controller is shown in the above figure. Mainly this block diagram
consists of the following essential blocks.
2.2.1 RF Transmitter and Receiver
2.2.2 PIC Microcontroller
2.2.3 GSM Modem
2.2.4 LCD Display
2.2.1 RF Transmitter and Receiver
The RF module, as the name suggests, operates at Radio Frequency. The
corresponding frequency range varies between 30 kHz & 300 GHz. In this
RF system, the digital data is represented as variations in the amplitude of
carrier wave. This kind of modulation is known as Amplitude Shift Keying
(ASK).
2.2.2 PIC Microcontroller
PIC is a family of modified Harvard Architecture made by Microchip
Technology and PIC referred to as Peripheral Interface Controller. PIC
devices are popular with both industrial developers and hobbyists due to
their low cost, wide availability, large user base, extensive collection of
application notes, availability of low cost or free development tools, serial
programming, and re-programmable Flash-memory capability.
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2.2.3 GSM Modem
A GSM modem is a specialized type of modem, which accepts a SIM card,
and operates over a subscription to a mobile operator, just like a mobile
phone. When a GSM modem is connected to a computer, this allows the
computer to use the GSM modem to communicate over the mobile
network. While these GSM modems are most frequently used to provide
mobile internet connectivity, many of them can also be used for sending and
receiving SMS and MMS messages.
2.2.4 LCD Display
A 16x2 LCD display is very basic module and is very commonly used in
various devices and circuits. These modules are preferred over seven
segments and other multi segment LEDs. The reasons being: LCDs are
economical; easily programmable; have no limitation of displaying special
& even custom characters (unlike in seven segments), animations and so on.
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2.3 CIRCUIT DIAGRAM
Fig 2.2 Circuit Diagram
RA0/AN02
RA1/AN13
RA2/AN2/VREF-/CVREF4
RA4/T0CKI/C1OUT6
RA5/AN4/SS/C2OUT7
RE0/AN5/RD8
RE1/AN6/WR9
RE2/AN7/CS10
OSC1/CLKIN13
OSC2/CLKOUT14
RC1/T1OSI/CCP216
RC2/CCP117
RC3/SCK/SCL18
RD0/PSP019
RD1/PSP120
RB7/PGD40
RB6/PGC39
RB538
RB437
RB3/PGM36
RB235
RB134
RB0/INT33
RD7/PSP730
RD6/PSP629
RD5/PSP528
RD4/PSP427
RD3/PSP322
RD2/PSP221
RC7/RX/DT26
RC6/TX/CK25
RC5/SDO24
RC4/SDI/SDA23
RA3/AN3/VREF+5
RC0/T1OSO/T1CKI15
MCLR/Vpp/THV1
U1
PIC16F877A
D7
14
D6
13
D5
12
D4
11
D3
10
D2
9D
18
D0
7
E6
RW
5R
S4
VS
S1
VD
D2
VE
E3
LCD1LM016L
RF Receiver
RF Transmitter
5V
GSM Modem
Rx
Tx
D1
D2
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2.3.1 Circuit Diagram Explanation
• Transmitter in the bus is programmed to send RF signal carrying the
bus details.
• When the bus approaches the bus stop, the (always-on) RF transmitter
(which is pre-programmed) sends RF signal carrying the details of the
bus number, route and its time of arrival.
• The always-on RF receiver at the bus stop receives the transmitted
signal and it is decoded using 16F877A microcontroller.
• Then, using GSM modem, the decoded bus details are sent to some
selected bus stops on the route.
• At Bus stops, GSM SIM card receives the information and the bus
details are displayed at the bus stop using a LCD monitor that is
interfaced to the microcontroller.
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CHAPTER 3
HARDWARE DESCRIPTIONS
3.1 PIC16F877A MICROCONTROLLER PIC 16F877 is one of the most advanced microcontroller from Microchip.
This controller is widely used for experimental and modern applications
because of its low price, wide application range, high quality and ease of
availability. It is ideal for applications such as machine control applications,
measurement devices, study purpose and so on. The PIC 16F877 features all
the components which modern microcontrollers normally have. The picture
of a PIC16F877 chip is shown below.
Fig 3.1 PIC IC
3.1.1 Features of PIC16F877
The features of PIC16F877A are given below
3.1.1.1 Special Features
• 100,000 erase/write cycle Enhanced Flash Program Memory
• Self-reprogrammable under software control
• Single-supply 5V In-Circuit Serial Programming
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• Watchdog Timer (WDT) with its own on-chip RC oscillator
• Programmable Code Protection
3.1.1.2 Peripheral Features
• Two 8-bit (TMR0, TMR2) timer/counter with pre-scalar
• One 16-bit timer/counter
• Parallel Slave Port (PSP): 40/44 pin-device only
• High performance RISC CPU:
• Only 35 single-word instructions to learn
• DC-20MHz clock input
Fig 3.2 PIC Pin Configuration
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3.2 RF TRANSMITTER
The TWS-434 is small, and is excellent for applications requiring short-
range RF remote controls. The transmitter module is only 1/3 the size of a
standard postage stamp, and can easily be placed inside a small plastic
enclosure.
TWS-434: The transmitter output is up to 8mW at 433.92MHz with a range
of approximately 400-foot (open area) outdoors. Indoors, the range is
approximately 200 foot, and will go through most walls.
The TWS-434 transmitter accepts both linear and digital inputs can operate
from 1.5 to 12 Volts-DC, and makes building a miniature hand-held RF
transmitter very easy. The TWS-434 is approximately the size of a standard
postage stamp.
Fig 3.3 RF Transmitter IC
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3.2.1 PIN Descriptions
Table 3.1 RF Transmitter PIN Descriptions
3.3 HT640 ENCODER
The 3 encoders are a series of CMOS LSIs for remote control system
applications. They are capable of encoding 18 bits of information, which
consists of N address bits, and 18_N data bits. Each address/data input is
externally ternary programmable if bonded out. It is otherwise set floating
internally.
Fig 3.4 HT640 Encoder IC
3.3.1 General Description
Various packages of the 3 encoders offer flexible combinations of
programmable address/data to meet various application needs. The
Pin No
Function
Name
1 Ground (0V) Ground 2 Serial data input pin Data 3 Supply voltage; 5V Vcc 4 Antenna output pin ANT
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programmable address/ data is transmitted together with the header bits via
an RF or an infrared transmission medium upon receipt of a trigger signal.
The capability to select a TE trigger type or a DATA trigger type further
enhances the application flexibility of the 318series of encoders.
3.3.2 Block diagram
Fig 3.5 HT640 Encoder Block Diagram
3.3.3 Features
• Operating voltage: 2.4V~12V
• Low power and high noise immunity CMOS technology
• Low standby current
• Three words transmission Built-in oscillator needs only 5% resistor
• Easy interface with an RF or infrared transmission media
• Minimal external components
3.4 RF RECEIVER
• The receiver needs between 4.5V and 5.5V to power up.
• The receiver will send any data it receives through Pin 2, which is
labeled "Digital Data Output". It is connected to the microcontroller
for decoding.
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• Pin 3, labeled "Linear Output/Test" is for testing the receiver, and we
will not be using it at all. It takes the receiver around 30 milliseconds
to start up.
Fig 3.6 RF Receiver IC
3.4.1 PIN Description
Table 3.2 PIN Configurations
Pin No Function Name
1 Ground (0V) Ground 2 Serial data output pin Data 3 Linear output pin; not connected NC 4 Supply voltage; 5V Vcc 5 Supply voltage; 5V Vcc 6 Ground (0V) Ground 7 Ground (0V) Ground 8 Antenna input pin ANT
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3.5 HT648 DECODER
The 3 decoders are a series of CMOS LSIs for remote control system
applications. They are paired with the 3 series of encoders. For proper
operation a pair of encoder/decoder pair with the same number of address
and data format should be selected.
3.5.1 General Description
The 318 series of decoders receives serial address and data from that series
of encoders that are transmitted by a carrier using an RF or an IR
transmission medium. It then compares the serial input data twice
continuously with its local address. If no errors or unmatched codes are
encountered, the input data codes are decoded and then transferred to the
output pins. The VT pin also goes high to indicate a valid transmission. The
318 decoders are capable of decoding 18 bits of information that consists of
N bits of address and 18–N bits of data. To meet various applications they
are arranged to provide a number of data pins whose range is from 0 to 8 and
an address pin whose range is from 8 to 18. In addition, the 318 decoders
provide various combinations of address/data number in different packages.
Fig 3.7 HT648 Decoder Block Diagram
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3.5.2 Features
• Operating voltage: 2.4V~12V
• Low power and high noise immunity CMOS technology
• Low standby current
• Capable of decoding 18 bits of information
• Pairs with HOLTEK’s 318 series of encoders
• 8~18 address pins
• 0~8 data pins
• Ternary address setting
• Two times of receiving check
• Built-in oscillator needs only a 5% resistor
• Valid transmission indictor
• Easily interface with an RF or an infrared transmission medium
• Minimal external components
3.6 GSM MODEM
A GSM modem is a wireless modem that works with a GSM wireless
network. A wireless modem behaves like a dial-up modem. The main
difference between them is that a dial-up modem sends and receives data
through a fixed telephone line while a wireless modem sends and receives
data through radio waves.
A GSM modem can be an external device or a PC Card / PCMCIA Card.
Typically, an external GSM modem is connected to a computer through a
serial cable or a USB cable. A GSM modem in the form of a PC Card /
PCMCIA Card is designed for use with a laptop computer. It should be
inserted into one of the PC Card / PCMCIA Card slots of a laptop computer.
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Like a GSM mobile phone, a GSM modem requires a SIM card from a
wireless carrier in order to operate.
Both GSM modems and dial-up modems support a common set of standard
AT commands. You can use a GSM modem just like a dial-up modem.
In addition to the standard AT commands, GSM modems support an
extended set of AT commands. These extended AT commands are defined
in the GSM standards. With the extended AT commands, you can do things
like:
• Reading, writing and deleting SMS messages.
• Sending SMS messages.
• Monitoring the signal strength.
• Monitoring the charging status and charge level of the battery.
• Reading, writing and searching phone book entries.
The number of SMS messages that can be processed by a GSM modem per
minute is very low only about six to ten SMS messages per minute.