RFID Based Toll Collection System

ABSTRACT

RFID Based Toll Collection System has really helped a lot in reducing the heavy congestion caused in the metropolitan cities of today. It is one of the easiest methods used to organize the heavy flow of traffic. When the car moves through the toll gate on any road, it is indicated on the RFID reader that it has crossed the clearing. The need for manual toll based systems is completely reduced in this methods and the tolling system works through RFID. The system thus installed is quite expedient reducing the time and cost of travellers since the tag can be deciphered from a distance.

The people travelling through this transport medium do not need anything else to get on a highway; instead the RFID tag carried by their vehicle does everything. A commuter travelling through this medium gets to know how much amount has been paid and how much money is left in the tag. It does not require the person to carry cash with him to pay the toll tax all the time. The long queue waiting for their turn is reduced, which in-turn reduces the consumption of fuel. The RFID toll payment systems are really used in preventing trespassing on borders. The software solution developed can ensure a smooth running of vehicles without any need for further development. The software controlling these RFID tags and readers is easy to implement.

            Here Basic idea is to develop the automatic challan system that can check for signal break by any vehicle. The RFID Reader reads the information like vehicles no. and automatically sends a report to the owner of vehicles and simultaneously information is given on the site itself through LCD.

INTRODUCTION

This project focuses on an electronic toll collection (ETC) system using Radio frequency Identification (RFID) technology. The RFID system uses tags, through which information embedded on the tags are read by RFID readers,  the proposed system eliminates the need for motorists and toll authorities to manually perform ticket payments and toll fee collections, respectively.

Thus it is a more efficient toll collection by reducing traffic and eliminating possible human errors. This system allows the vehicle drivers to pass the toll tax booths without stopping at the toll booths. The toll amount is deducted from the RFID card. This RFID card is rechargeable and account is stored on the records. This system will have two benefits. First benefit is that movement of traffic will be much faster as user will not wait to give the money because, driver has to just show the RFID card in-front of the card reader.

Second benefit is that driver doesn't have to carry the money each time. He will just recharge the RFID card by certain amount and will use this card each time he travels. This is little bit similar to using credit cards.

 HARDWARE IMPLIMENTATION

 BLOCK DIAGRAM

The below figure shows block diagram of RFID based toll collection:-

WORKING

IR Receiver detects the vehicle and sends the information to Microcontroller. RFID reader reads the RFID card and given to microcontroller. Microcontroller checks weather the ID card is valid or not. If it is valid it checks the balance, if there is sufficient balance then displays in LCD and opens gate. If there is no sufficient balance it gives recharge option. Then buzzer gets on.

If it is valid card then microcontroller gives information to motor. Then motor opens the gate. PC interface is used for recharge option when there is insufficient balance.

 HARDWARE DESCRIPTION

This project consists of following hardware components: 

    1.  P89V51RD2 MICROCONTROLLER.

    2. RFID CARD

    3. RFID READER

    4. LIQUID CRYSTAL DISPLAY

    5. IR RECEIVER

    6. IR TRANSMITTER

    7. MOTOR DRIVER

    8. DC MOTOR

    9. BUZZER

   10. SWITCH

   11. KEYPAD

  MICROCONTROLLER

       DESCRIPTION                                                          

       P89V51RD2 is an 80C51 microcontroller with 64 kB Flash and 1024 bytes of data RAM. The P89V51RD2 device contains a non-volatile 16kb/32kb/64kb flash program memory that is  both parallel programmable and serial in-system and in-application programmable.                                                                                    

 In-system programming (ISP) allows the user to download new code while the microcontroller sits in the application. In-Application Programming (IAP) means that the microcontroller fetches new program code and reprograms itself while in the system.

This allows for remote programming over a modem link. A default serial loader (boot loader) program in ROM allows serial in-system programming of the flash memory via the UART without the need for a loader in the flash code. For in-application programming, the user program erases and reprograms the flash memory by use of standard routines contained in ROM. This device executes one machine cycle in 6 clock cycles, hence providing twice the speed of a conventional 80c51.

 An OTP configuration bit lets the user select conventional 12 clock timing if desired. This device is a single-chip 8-bit microcontroller manufactured in advanced CMOS process and is a derivative of the 80c51 microcontroller family. The instruction set is 100% compatible with the 80c51 instruction set. The device also has four 8-bit I/O ports, three 16-bit timer/event counters, a multi-source, Four-priority-level, nested interrupt structure, an enhanced UART and on-chip oscillator and timing circuits. The added features of the p89v51rd2 makes it a powerful microcontroller for applications that require pulse width modulation, high-speed I/O and up/down counting capabilities such as motor control.     

A key feature of the P89V51RD2 is its X2 mode option. The design engineer can choose to run the application with the conventional 80C51 clock rate (12 clocks per machine cycle) or select the X2 mode (6 clocks per machine cycle) to achieve twice the throughput at the same clock frequency. Another way to benefit from this feature is to keep the same performance by reducing the clock frequency by half, thus dramatically reducing the EMI. The capability to field/update the application firmware makes a wide range of applications possible.

 

         FEATURES

•     80C51 Central Processing Unit.
•   5 V Operating voltages from 0 to 40 MHz. 
•       64 kb of on-chip Flash program memory with ISP (In-System Programming) and IAP (In-        Application Programming).
•     Supports 12-clock (default) or 6-clock mode selection via software or ISP. 
•      SPI (Serial Peripheral Interface) and enhanced UART. 
•         PCA (Programmable Counter Array) with PWM and Capture/Compare functions. 
•      Four 8-bit I/O ports with three high-current Port 1 pins (16 mA each). 
•     Three 16-bit timers/counters. 
•          Programmable Watchdog timer (WDT) 
•     Eight interrupt sources with four priority levels 
•       Second DPTR register 
•        Low EMI mode (ALE inhibit) 
•      TTL- and CMOS-compatible logic levels 
•    Brown-out detection. 
•     Low power

Ø  Power down modes with external wake-up

Ø  Idle mode    

•        PDIP40,PLCC44 and TQFP44 packages. 

PIN CONFIGURATION  

PIN DESCRIPTION

VCC: supply voltage

GND : Ground

PORT 0:  Port 0 is an 8-bit open drain bi-directional I/O port. Port 0 pins that have ‘1’s written to them float, and in this state can be used as high-impedance inputs.

Port 0 is also the multiplexed low-order address and data bus during accesses to external code and data memory. In this application, it uses strong internal

pull-ups when transitioning to ‘1’s. Port 0 also receives the code bytes during the external host mode programming, and outputs the code bytes during the external host mode verification. External pull-ups are required during program verification or as a general purpose I/O port.

PORT 1:  is an 8-bit bi-directional I/O port with Port 1: Port 1 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 1 pins are pulled high by the internal pull-ups when ‘1’s are written to them and can be used as inputs in this state. As inputs, Port 1 pins that are externally pulled LOW will source current (IIL)because of the internal pull-ups. P1.5, P1.6, P1.7 have high current drive of 16 mA. Port 1 also receives the low-order address bytes during the external host mode programming and verification.

PORT 2: Port 2 is an 8-bit bi-directional I/O port with internal pull-ups. Port 2 pins are pulled HIGH by the internal pull-ups when ‘1’s are written to them and can be used as inputs in this state. As inputs, Port 2 pins that are externally pulled LOW will source current (IIL)

PORT 3: Port 3 is an 8-bit bidirectional I/O port with internal pull-ups. Port 3 pins are pulled HIGH by the internal pull-ups when ‘1’s are written to them and can be used as inputs in this state. As inputs, Port 3 pins that are externally pulled LOW will source current (IIL) because of the internal pull-ups. Port 3 also receives some control signals and a partial of high-order address bits during the external host mode programming and verification

RST (RESET INPUT):  While the oscillator is running, a HIGH logic stateon this pin for two machine cycles will reset the device. If the PSEN pin is driven by a HIGH-to-LOW input transition while the RST input pin is held HIGH, the device will enter the external host mode, otherwise the device will enter the normal operation mode.

ALE/PROG:  ALE is the output signal for latching the low byte of the address during an access to external memory. This pin is also the programming pulse input (PROG) for flash programming. Normally the ALE [1] is emitted at a constant rate of 1 6 the crystal frequency[2] and can be used for external timing and clocking. One ALE pulse is skipped during each access to external data memory. However, if AO is set to ‘1ALE is disabled.

PSEN: Program Store Enable: PSEN is the read strobe for external program memory. When the device is executing from internal program memory, PSEN is inactive (HIGH). When the device is executing code from external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped during each access to external data memory. A forced HIGH-to-LOW input transition on the PSEN pin while the RST input is continually held HIGH for more than 10 machine cycles will cause the device to enter external host mode programming.

EA(external access enable):  External Access Enable: EA must be connected to VSS in order to enable the device to fetch code from the external program memory. EA must be strapped to VDD for internal program execution.

 However, Security lock level 4 will disable EA, and program execution is only possible from internal program memory. The EA pin can tolerate a high voltage of 12 V.

XTAL1: Crystal 1: Input to the inverting oscillator amplifier and input to the internal clock generator circuits.

XTAL2: Crystal 2: Output from the inverting oscillator amplifier.

MEMORY ORGANIZATION

The device has separate address spaces for program and data memory.

Flash program memory

There are two internal flash memory blocks in the device. Block 0 has 64 Kbytes and contains the user’s code. Block 1 contains the Philips-provided ISP/IAP routines and may be enabled such that it overlays the first 8 Kbytes of the user code memory.

The 64 kb Block 0 is organized as 512 sectors, each sector consists of 128 bytes. Access to the IAP routines may be enabled by clearing the BSEL bit in the FCF

register. However, caution must be taken when dynamically changing the BSEL bit.

Since this will cause different physical memory to be mapped to the logical program address space, the user must avoid clearing the BSEL bit when executing user code within the address range 0000H to 1FFFH.

Data RAM memory

The data RAM has 1024 bytes of internal memory. The device can also address up to64 kB for external data memory.

 Flash memory In-Application Programming

 Flash organization

The P89V51RD2 program memory consists of a 64 kb block. An In-System Programming (ISP) capability, in a second 8 kb block, is provided to allow the user code to be programmed in-circuit through the serial port. There are three methods of erasing or programming of the Flash memory that may be used. First, the Flash may be programmed or erased in the end-user application by calling low-level routines through a common entry point (IAP). Second, the on-chip ISP boot loader may be invoked.

This ISP boot loader will, in turn, call low-level routines through the same common entry point that can be used by the end-user application. Third, the Flash may be programmed or erased using the parallel method by using a commercially available EPROM programmer which supports this device .

In-System Programming (ISP)                                                        

                                     In-System Programming is performed without removing the microcontroller from the system. The In-System Programming facility consists of a series of internal hardware resources coupled with internal firmware to facilitate remote programming of the P89V51RD2 through the serial port. This firmware is provided by Philips and embedded within each P89V51RD2 device. The Philips In-System Programming facility has made in-circuit programming in an embedded application possible with a minimum of additional expense in components and circuit board area. The ISP function uses five pins (VDD, VSS, TxD, RxD, and RST). Only a small connector needs to be available to interface your application to an external circuit in order to use this feature.

       RFID  BASIC

DESCRIPTION

RFID stands for Radio-Frequency Identification. The acronym refers to small electronic devices that consist of a small chip and an antenna. The chip typically is capable of carrying 2,000 bytes of data or less.  

The RFID device serves the same purpose as a bar code or a magnetic strip on the back of a credit card or ATM card; it provides a unique identifier for that object. And, just as a bar code or magnetic strip must be scanned to get the information, the RFID device must be scanned to retrieve the identifying information. 

            A significant advantage of RFID devices over the others mentioned above is that the RFID device does not need to be positioned precisely relative to the scanner. We're all familiar with the difficulty that store checkout clerks sometimes have in making sure that a

Bar code can be read. And obviously, credit cards and ATM cards must be swiped through a special reader.  In contrast, RFID devices will work within a few feet (up to 20 feet for high frequency devices) of the scanner.

For example, you could just put all of your groceries or purchases in a bag, and set the bag on the scanner. It would be able to query all of the RFID devices and total your purchase immediately. RFID technology has been available for more than fifty years. It has only been recently that the ability to manufacture the RFID devices has fallen to the point where they can be used as a "throwaway" inventory or control device. 

           One reason that it has taken so long for RFID to come into common use is the lack of standards in the industry. Most companies invested in RFID technology only use the tags to track items within their control; many of the benefits of RFID come when items are tracked from company to company or from country to country.  

RFID WORKING

A Radio-Frequency Identification system has three parts:

•  A scanning antenna  
• A transceiver with a decoder to interpret the data   
•    A transponder - the RFID tag - that has been programmed with information. 

The scanning antenna puts out radio-frequency signals in a relatively short range. The RF radiation does two things: 

• It provides a means of communicating with the transponder (the RFID tag)

• It provides the RFID tag with the energy to communicate (in the case of passive RFID tags). 

  This is an absolutely key part of the technology; RFID tags do not need to contain batteries, and can therefore remain usable for very long periods of time (maybe decades).   The scanning antennas can be permanently affixed to a surface; handheld antennas are also available. They can take whatever shape you need; for example, you could build them into a door frame to accept data from persons or objects passing through. 

             When an RFID tag passes through the field of the scanning antenna, it detects the activation signal from the antenna. That "wakes up" the RFID chip, and it transmits the information on its microchip to be picked up by the scanning antenna. 

         In addition, the RFID tag may be of one of two types. Active RFID tags have their own power source; the advantage of these tags is that the reader can be much farther away and still get the signal.

 Even though some of these devices are built to have up to a 10 year life span, they have limited life spans. Passive RFID tags, however, do not require batteries, and can be much smaller and have a virtually unlimited life span. RFID tags can be read in a wide variety of circumstances, where barcodes or other optically read technologies are useless. 

 The tag need not be on the surface of the object (and is therefore not subject to wear)   The read time is typically less than 100 milliseconds   Large numbers of tags can be read at once rather than item by item. 

 RFID TAG                                                                                  

An RFID tag is comprised of a microchip containing identifying information and an antenna that transmits this data wirelessly to a reader. At its most basic, the chip will contain a serialized identifier, or license plate number, that uniquely identifies that item, Similar to the way many bar codes are used today.

A key difference, however is that RFID tags have a higher data capacity than their bar code counterparts. This increases the options for the type of information that can be encoded on the tag, including the manufacturer, batch or lot number, weight, ownership, destination and history (such as the temperature range to which an item has been exposed).

             In fact, an unlimited list of other types of information can be stored on RFID tags, depending on application needs. An RFID tag can be placed on individual items, cases or pallets for identification purposes, as well as on fixed assets such as trailers, containers, totes, etc

 TYPES OF TAGS            

           Active tag: An RFID tag is an active tag when it is equipped with a battery that can be used as a partial or complete source of power for the tag's circuitry and antenna. Some active tags contain replaceable batteries for years of use; others are sealed units. (Note that it is also possible to connect the tag to an external power source.)

Passive tag : A passive tag is an RFID tag that does not contain a battery; the power is supplied by the reader. When radio waves from the reader are encountered by a passive RFID tag, the coiled antenna within the tag forms a magnetic field. The tag draws power from it, energizing the circuits in the tag. The tag then sends the information encoded in the tag's memory.

 RFID READER

  An RFID reader is a device that is used to interrogate an RFID tag. The reader has an antenna that emits radio waves; the tag responds by sending back its data. 

    A number of factors can affect the distance at which a tag can be read (the read range). The frequency used for identification, the antenna gain, the orientation and polarization of the reader antenna and the transponder antenna, as well as the placement of the tag on the object to be identified will all have an impact on the RFID system’s read range.  When a reader broadcasts radio waves, all tags designated to respond to that frequency and within range will respond.

A reader also has the capability to communicate with the tag without a direct line of sight, depending on the radio frequency and the type of tag (active, passive, or semi passive) used. The RF transceiver is the source of the RF energy used to activate and power the passive RFID tags. The RF transceiver may be enclosed in the same cabinet as the reader or it may be a separate piece of equipment.

When provided as a separate piece of equipment, the transceiver is commonly referred to as an RF module. The RF transceiver controls and modulates the radio frequencies that the antenna transmits and receives. The transceiver filters and amplifies the backscatter signal from a passive RFID tag.

LCD INTERFACING:

  PIC16F877A is used here to display message on the Hitachi HD44780-based character LCD module. PIC16F877A is 8-bit microcontroller based on reduced instruction set computer (RISC) architecture. It has 8kx14-bits flash program memory, 368 bytes of RAM. Here PIC16F877A microcontroller is connected to HD44780 LCD in 4-bit interface data, only four bus lines (DB4 to DB7) are used for data transfer. Bus lines DB0 to DB3 are having no connection with microcontroller. The data transfer between the HD44780U and the PIC16F877A is completed after the 4-bit data has been transferred twice. 

The ENABLE pin is used to latch the data present on the data pins. A HIGH - LOW signal is required to latch the data. The LCD interprets and executes our command at the instant the EN line is brought low. If you never bring EN low, your instruction will never be executed.

       MAX232:

 DESCRIPTION

The MAX232 is an integrated circuit that converts signals from an RS-232 serial port to signals suitable for use in TTL compatible digital logic circuits. The MAX232 is a dual driver/receiver and typically converts the RX, TX, CTS and RTS signals. The drivers provide RS-232 voltage level outputs (approx. ± 7.5 V) from a single + 5 V supply via on-chip charge pumps and external capacitors. This makes it useful for implementing RS-232 in devices that otherwise do not need any voltages outside the 0 V to + 5 V range, as power supply design does not need to be made more complicated just for driving the RS-232 in this case. The receivers reduce RS-232 inputs (which may be as high as ± 25 V), to standard 5 V TTL levels. These receivers have a typical threshold of 1.3 V, and a typical hysteresis of 0.5 V. The later MAX232A is backwards compatible with the original MAX232 but may operate at higher baud rates and can use smaller external capacitors – 0.1 μF in place of the 1.0 μF capacitors used with the original device.

The newer MAX3232 is also backwards compatible, but operates at a broader voltage range, from 3 to 5.5V.

 VOLTAGE LEVELS

It is helpful to understand what occurs to the voltage levels. When a MAX232 IC receives a TTL level to convert, it changes a TTL Logic 0 to between +3 and +15V, and changes TTL Logic 1 to between -3 to -15V, and vice versa for converting from RS232 to TTL. This can be confusing when you realize that the RS232 Data Transmission voltages at a certain logic state are opposite from the RS232 Control Line voltages at the same logic state. 

 

APPLICATIONS

•  Portable Computers 
•   Low-Power Modems 
•   Interface Translation 
•   Battery-Powered RS-232 Systems 
•    Multi drop RS-232 Networks

 IR TRANSMITTER & RECEIVER:-

    

 DESCRIPTION

Infrared (IR) light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres ( µm), and extending conventionally to 300 µm. These wavelengths correspond to a frequency range of approximately 1 to 400 THz, and include most of the thermal radiation emitted by objects near room temperature.

Microscopically, IR light is typically emitted or absorbed by molecules when they change their rotational-vibrational movements.

 IR TRANSMITTING LED 

Common infrared LED that emits infrared rays has the same appearance with visible light LED. It’s appropriate operating voltage is around 1.4V and the current is generally smaller than 20mA. Current limiting resistances are usually connected in series in the infrared LED circuits to adjust the voltages, helping the LEDs to be adapted to different operating voltages.

 IR RECEIVER LED

These IR Receiver LEDs receive the IR modulated light  generated by adding pulse voltage with specific frequency on the IR Transmitting diode. They should be placed at a distance which is in direct facing  with the IR emitting LEDs.

In order to lengthen its controlling distance, infrared LED should be operated under pulse state as the effective transmitting distance of the pulsed light (modulated light) is in proportion with the wind-induced current of the pulses. Thus, by increasing the peak value (Ip) of the pulses, the emitting distance of the infrared LED can also be lengthened. One way to increase Ip is to diminish the duty ratio of the pulse; that is to reduce the width of the pulse (T). Through reducing the duty ratio of the pulses, the emitting distance for small power infrared LED can also be increased in a large extent.  

   

     POWER SUPPLY UNIT

 

DESCRIPTION      

                                           

A power supply is an electronic device that supplies electric energy to an electrical load. The primary function of a power supply is to convert one form of electrical energy to another and, as a result, power supplies are sometimes referred to as electric power converter. Some power supplies are discrete, stand-alone devices, whereas others are built into larger devices along with their loads. Examples of the latter include power supplies found in desktop computers and consumer electronics devices.

TYPES OF POWER SUPPLY:

There are many types of power supply. Most are designed to convert high voltage AC mains electricity to a suitable low voltage supply for electronics circuits and other devices. A power supply can by broken down into a series of blocks, each of which performs a particular function. For example a 5V regulated supply:

Each of the blocks is described in more detail below:

• Transformer - steps down high voltage AC mains to low voltage AC.
• Rectifier - converts AC to DC, but the DC output is varying.
• Smoothing - smooth’s the DC from varying greatly to a small ripple.
• Regulator - eliminates ripple by setting DC output to a fixed voltage.

Power supplies made from these blocks are described below with a circuit diagram and a graph of their output:

• Transformer only
• Transformer + Rectifier
• Transformer + Rectifier + Smoothing

Transformer + Rectifier + Smoothing + Regulator

Transformer: Transformers convert AC electricity from one voltage to another with little loss of power. Transformers work only with AC and this is one of the reasons why mains electricity is AC. Step-up transformers increase voltage, step-down transformers reduce voltage. Most power supplies use a step-down transformer to reduce the dangerously high mains voltage (230V in UK) to a safer low voltage.

Rectifier: There are several ways of connecting diodes to make a rectifier to convert AC to DC. The bridge rectifier is the most important and it produces full-wave varying DC. A full-wave rectifier can also be made from just two diodes if a centre-tap transformer is used, but this method is rarely used now that diodes are cheaper.

Regulator: Voltage regulator ICs are available with fixed (typically 5, 12 and 15V) or variable output voltages. They are also rated by the maximum current they can pass. Negative voltage regulators are available, mainly for use in dual supplies. Most regulators include some automatic protection from excessive current ('overload protection') and overheating ('thermal protection').

Power supply circuit  :

From a 12V Adaptor, input is taken into the power supply unit via a DC Socket. A 5V regulator circuit is designed using LM7805 as shown below which is needed for microcontroller as supply voltage.  A 12V Bridge rectifier in between the DC Socket and LM7805 is used. This Bridge continues to provide supply even in case of Power- pin polarity inversion at the DC Socket.

 

The capacitor C3 is used to filter the Bridge Rectifier o/p. C4 is to filter the ripples at the input of LM7805. C2 at the LM7805 o/p is again to get a smooth DC o/p. A general circuit and output waveform of a Bridge rectifier is as shown below:

 DC MOTOR

DC stands for "direct current". A DC motor is an electric electric motor that uses electricity and a magnetic field to produce torque, which turns the DC motor. A DC motor consists of two magnets of opposite polarity and an electric coil. When a power supply is added to the coil electric current flows through in a circuit and generates a small magnetic field. The repellent and attractive electromagnetic forces of the magnets provide the torque that causes the armature to turn.  

Magnets are polarized, with a positive and a negative side. A DC motor uses the attraction between opposite poles and the repulsion of like poles to convert electric energy into kinetic energy. As the magnets within the DC motor attract and repel one another, the motor turns.

The magnetic force on the armature works perpendicular to both wire and magnetic field. An electric switch called a commutator reverses the direction of the electric current in the armature twice every cycle.

 The poles of the electromagnet push and pull against the permanent magnets on the outside of the motor. As the poles of the armature electromagnet pass the poles of the permanent magnets, the commutator reverses the polarity of the armature electromagnet. During that instant of switching polarity, inertia keeps the motor going in the proper direction.

If an electric current goes through the coil, the motor will act like a generator and produce an electric motive force (EMF). When the motor spins it produces a voltage called the back EMF because it opposes the applied voltage on the motor. Therefore, the voltage drop across the motor consists of the voltage drop from the back EMF and the voltage drop from the internal resistance of the rotation of the armature.

DC MOTOR INTERFACING WITH CONTROLLER:         

                              Usually H-bridge is preferred way of interfacing a DC motor. These days many IC manufacturers have H-bridge motor drivers available in the market like L293D is most used H-Bridge driver IC. H-bridge can also be made with the help of transistors and MOSFETs etc. rather of being cheap, they only increase the size of the design board, which is sometimes not required so using a small 16 pin IC is preffered for this purpose.

H-Bridge:

The name "H-Bridge" is derived from the actual shape of the switching circuit which control the motion of the motor. It is also known as "Full Bridge". Basically there are four switching elements in the H-Bridge as shown in the figure below. 

 

 

As you can see in the figure above there are four switching elements named as "High side left", "High side right", "Low side right", "Low side left". When these switches are turned on in pairs motor changes its direction accordingly. Like, if we switch on High side left and Low side right then motor rotate in forward direction, as current flows from Power supply through the motor coil goes to ground via switch low side right. This is shown in the figure below. Similarly, when you switch on low side left and high side right, the current flows in opposite direction and motor rotates in backward direction. This is the basic working of H-Bridge.

Dual H-Bridge Motor Driver (L293D)
      L293D is a dual H-Bridge motor driver, So with one IC we can interface two DC motors which can be controlled in both clockwise and counter clockwise direction and if you have motor with fix direction of motion the you can make use of all the four I/Os to connect up to four DC motors. L293D has output current of 600mA and peak output current of 1.2A per channel. Moreover for protection of circuit from back EMF ouput diodes are included within the IC. The output supply (VCC2) has a wide range from 4.5V to 36V, which has made L293D a best choice for DC motor driver

Buzzer

     Instantly, current shoots downward to the brass contactor screw. Since the screw is touching the vibrator arm, the cur- rent continues on its way into the coil. Out of the coil it streaks past the closed code key and back to the battery.                                                            

 As in the electric pencil, this flow of current creates a magnetic field around the iron bolt. Having become an electro- magnet, the bolt attracts the vibrator arm. But as the arm starts to swing toward the bolt, it opens the circuit. Hence, the current stops.

As a result, the magnetic field collapses, allowing the vibrator arm to spring back against the contactor. With the circuit now restored, current starts flowing again and the cycle starts anew.

No matter how quickly we press and release the code key, the current will still make hundreds of round trips through the circuit. And because of the resulting rapid motions of the vibrator arm, a buzzing sound is heard. Not only is the code set fun to build, but it is even more fun to use, especially with a fellow operator. So that both of you can send as well as receive messages, you will want to build two identical sets of buzzers and code keys. They’re really not hard to make. For each set you will need the following materials.

FLASH MAGIC SOFTWARE

INTRODUCTION

This is a Tool from Philips for Programming the controllers that are flash programmable and that supports serial programming of devices. Flash microcontroller can be erased and re-written as many times as possible. The Boot loader Inside the Chip understands the protocol received from computer through serial port. Flash Magic identifies the hardware when the controller chip is inserted. Program for the target microcontroller can be now either read back or sent as Intel format HEX file. Support locking of devices can be done to prevent reading back of programmed chip. After locking the chip can still be erased and used again for loading new programs.

 FEAURES

• Support major Philips devices 
•  Lock of programs in chip supported to prevent program copying
• ZIF socket on-board Compatible 40 pin Microcontrollers 
•   Auto Erase before writing and Auto Verify after writing
• Informative status bar and access to latest programmed file 
• Simple and Easy to use

CIRCUIT DIAGRAM

Circuit diagram for RF ID BASED TOLL COLLECTION SYSTEM:

WORKING:

 IR Receiver detects the vehicle and sends the information to Microcontroller. RFID reader reads the RFID card and given to microcontroller. Microcontroller checks weather the ID card is valid or not. If it is valid it checks the balance, if there is sufficient balance then displays in LCD and opens gate. If there is no sufficient balance it gives recharge option. Then buzzer gets on.

If it is valid card then microcontroller gives information to motor. Then motor opens the gate. PC interface is used for recharge option when there is insufficient balance.

  FLOWCHART

ADVANTAGES AND DISADVANTAGES

 

ADVANTAGES

• Makes travelling more convenient, reduces travel times especially during festive  seasons when traffic tends to be heavier than normal. 
•  Saves fuel and thus increases fuel economy Reduces auto emissions 
•   Increase highway capacity. Processes 250 – 300% more vehicles per lane, 4 Reduces wait time at toll booths 
•  reducing delays and traffic congestion
• Easy mounting, easy to operate (user friendly) 
•   Enables very specific detection of vehicle
•     Simultaneous multiple detection of vehicles are possible using RFID

 DISADVANTAGES

•   Low frequency results in lower maximum data rate, although it is fast enough to allow multiple transmissions to increase reliability
•   Tag usually requires power from vehicle (active tag).
• Tag installation is not as convenient as that of a windshield-mounted tag
• Moderate difficulty in duplicating tags. 

APPLICATIONS

• Automatic Vehicle identification.
• Inventory Management.
• Work-in-Process .
• Container/ Yard Management . 
•  Document/ Jewelry tracking .
• Patient Monitoring

 

SCOPE FOR FUTURE DEVELOPMENT

       implementation of automatic money debit system :

                        In our project now we are implementing the smart card mechanism for the payment of the toll amount paid by the vehicle owner. When the vehicle comes on the load cell plate for weighing ,at that time the vehicle owner has to swap his smart card in the debit machine .So, desired amount of toll amount will be deducted from the account of owner.       

       Here we can also implement the automatic debit system. In this system we have to treat the RFID card also as the smart card. In the RFID card we have now vehicle number in the code format. So, we can combine the RFID card with smart card as both are the different forms of basic principle of Bar code.

     Implementation of image processing for centralize data recording                

                               In our present concept we are only using the RFID system for vehicle detection. So we can extend the scope of this concept in other way for centralize data recording. For that purpose we can use the IR courten at the entry gate which is followed by the Camera which will be continuously capturing the images of the vehicles entering into the toll plaza. And the third step the RFID is collecting the vehicle number.    

                   Now when the vehicle passes through the IR courten it tresses the outline of the vehicle, in the next step the camera will take the image of the vehicle & followed by the RFID to record the data related to the vehicle. The load cell weighs the vehicle & classifies it into two categories as light & heavy vehicle respectively. The whole data collected together & sent to the centralize server which will store it for stipulated time. This application will help in detecting the vehicles in the crime cases like terrorism & smuggling of goods & it will also reduce the load on check posts.

CONCLUSION

By doing automation of toll plaza we can have the best solution over money loss at toll plaza by reducing the man power required for collection of money and also can reduce the traffic indirectly resulting in reduction of time at toll plaza. 

  In our project we have introduced the techniques such as Radio Frequency Identification. This technique will include the RFID tag & reader which in coordination with each other can be used to detect the vehicle identity.

 The load cell plate which is introduced for weighing the vehicles so as to classify them in different categories as light & heavy vehicles.

 The IR Transreceiver is used for detecting the presence of vehicle at different locations which will act as the gate pass to the toll plaza.

 By  effectively utilizing these three techniques at different stages of our project we are able to represent the automation in toll plaza which will reduce the complete processing time by few seconds which is very important as well as helps to reduce money leakage in a very cost effective manner.