* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download View/Open - Library@Atmiya
Survey
Document related concepts
Current source wikipedia , lookup
Electronic paper wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Voltage optimisation wikipedia , lookup
Alternating current wikipedia , lookup
Power electronics wikipedia , lookup
Mains electricity wikipedia , lookup
Two-port network wikipedia , lookup
Surge protector wikipedia , lookup
Semiconductor device wikipedia , lookup
Buck converter wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Liquid-crystal display wikipedia , lookup
Immunity-aware programming wikipedia , lookup
Transcript
“Transforming Live, inventing Future” A Project Report On RFID BASE SECURITY SYTEM By 1. BANSIKALARIA (106030311024) 2. BHAVI PARMAR (106030311018) DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING ATMIYA INSTITUTE OF TECHNOLOGY AND SCIENCE FOR DIPLOMA STUDIES, RAJKOT- 360005. [2012– 2013] A Project Report On RFID BASE SECURITY SYSTEM In partial fulfilment of requirements for the degree of Diploma of Engineering In EC Engineering Submitted By: Under the Guidance of 1. Bansi kalaria-106030311024Mr.Nirajbhardwani 2. Bhavi parmar-106030311018 DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING ATMIYA INSTITUTE OF TECHNOLOGY AND SCIENCE FOR DIPLOMA STUDIES, RAJKOT- 360005. [2012 – 2013] CERTIFICATE This is to certify that the project entitled “RFID base door lock security system” has been carried out by the team under my guidance in partial fulfilment of the Diploma of Engineering in Electronics & Communication in GTU during the academic year 2012-2013 (Semester-5). Team: 1. 2. BansiKalaria BhaviParmar Date: Place: Guide (Prof.Niraj Bhardwani) Head, EC Department Principal External guide ACKNOWLEGEMENT I greatly thank my faculty guide of the college Mr.NirajBhardwani. I’m also thankful to my external guide and chairperson of the industry I visited Mr. Viral Panchasara. Mr. Viral Panchasara is a very genuine person and gave me training giving time from his busy schedule. Lastly I heartily thank all my friends, parents and who have guided and Motivated us directly or indirectly to complete my project successfully. BansiKalaria Bhavi Parmar ABSTRACT Radio-frequencyidentification (RFID) based access-control system allows only authorised persons to enter a particular area of an establishment. The authorised persons are provided with uniquetags, using which they can access that area. The system is based on microcontroller AT89C52 and comprises an RFID module for displaying the status and a relay for opening the door. User trying to open the door by placing an RFID tag near the RFID reader. Mightbe familiar with RFID systems as seen in access control, contactless payment systems, product tracking and inventory control, etc. basically, an RFID system consists of three components antenna or coil, a transreceive (with decoder) and a transponder (RFID tag) electronically programmed with unique information. It is a very typical RFID system. In every RFID system, the transponder tags contain unique identifying information. This information can be as little as a single binary bit or a large array of bits representing such things as an identity code, personal medical information or literally any type of information that can be stored in digital binary format. LIST OF FIGURE Figure 1 Basic block diagram of RFID ................................................................................................. 13 Figure 2 PCB layout.............................................................................................................................. 14 Figure 3 Component of pcb layout ....................................................................................................... 15 Figure 4 Circuit diagram of RFID......................................................................................................... 16 Figure 5 RFID reader Modual ............................................................................................................... 18 Figure 6 Internals diagram of RFID antenna ......................................................................................... 19 Figure 7 AT89c8051 .............................................................................................................................. 20 Figure 8 PIN diagram of AT89c8051...................................................................................................... 21 Figure 9 MAX232 ................................................................................................................................... 24 Figure 10 Pin diagram of MAX232 ........................................................................................................ 25 Figure 11 Lcd display ............................................................................................................................. 26 Figure 12 Sin pin connector .................................................................................................................. 27 Figure 13 Pull-up resistor ...................................................................................................................... 28 Figure 14 LED ........................................................................................................................................ 29 Figure 15 RFID tag ................................................................................................................................. 30 Figure 16 Diode ..................................................................................................................................... 31 Figure 17 Capacitor ............................................................................................................................... 33 ABRIVATION USED IN REPORT 1. RFID-Radio frequency identification system 2. LCD-Liquid crystal display 3. LED-Light emitting diode 4. ALE-Address latch enable 5. RST-Reset enable 6. PSEN-Program store enable 7. EA-External access enables 8. ATM-Automatic tailor machine 9. DVD-Digital Versatile Disc Contents ACKNOWLEGEMENT ..................................................................................................................... 4 ABSTRACT........................................................................................................................................ 5 LIST OF FIGURE............................................................................................................................... 6 ABRIVATION USED IN REPORT ................................................................................................... 7 CHAPTER-1 ....................................................................................................................................... 9 1.1 Introduction ................................................................................................................................... 9 1.2 What is RFID? .............................................................................................................................. 9 1.3 What can RFID are used for?...................................................................................................... 11 1.4 RFID limitation ........................................................................................................................... 11 CHAPTER-2 ..................................................................................................................................... 13 2.1 Basic block diagram .................................................................................................................... 13 2.2 PCB layout .................................................................................................................................. 14 CHAPTER-3 ..................................................................................................................................... 16 3.1 Circuit diagram ........................................................................................................................... 16 3.2Circuit description ........................................................................................................................ 17 CHAPTER-4 ..................................................................................................................................... 20 4.1 Components description.............................................................................................................. 20 CHAPTER-5 ..................................................................................................................................... 35 5.1 Coding ......................................................................................................................................... 35 Advantages........................................................................................................................................ 40 Future scope ...................................................................................................................................... 40 Other application............................................................................................................................... 41 Conclusion ........................................................................................................................................ 42 Reference .......................................................................................................................................... 43 CHAPTER-1 1.1 Introduction This project aimed to develop a wireless system to detect and allow only the authorized persons. The system was based on RFID technology and consists of a passive RFID tag. The passive micro transponder tag collects power from the 125 KHz magnetic field generated by the base station, gathers information about the tag ID and sends this information to the base station. The base station receives, decodes and checks the information available in its database and Manchester code was used to send those, information. The system performed as desired with a 10cm. diameter antenna attached to the transponder. The base station is built by using the popular 8051 family micro controller. It gets the tag ID and if the tag is stored in its memory then the microcontroller will allow the person inside. RFID reader module, are also called as interrogators. They convert radio waves returned from the RFID tag into a form that can be passed on to controllers, which can make use of it. RFID tags and readers have to be tuned to the same frequency in order to communicate. RFID systems use many different frequencies, but the most common and widely used reader frequency is 125 KHz. The L-sp2 and L-sp3 security gates are part of an advanced security system to protect the assets of public or private institutions. Using the most advanced technology, these barriers detect and accurately identify items marked with RFID tags, providing libraries, museums and archives with a modern and flexible security system. 1.2 What is RFID? The RFID device serves the same purpose as barcode 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 Barcode or magnetic strip must be scanned to get the information, the RFID device must be scanned to retrieve the identifying information. RFID stands of RFID. The acronym refers to small electronic device that consists of a small chip and an antenna. The chip typically is capable of carrying 2,000 bytes of data or less. How RFID works? 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 RFID works better than barcodes. 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 are all familiar with the difficulty that store checkout clerks sometimes have in making sure that a barcode can be read. And obviously, credit cards and ATM cards must be swiped through a special reader. Sr. no Barcode RFID 1 Rely on the user to make contact to the Do not require contact with reader, reader, hence cannot be read from a hence can be read from a distance. distance 2 In Barcode, only one card read at a time Multiple read at a time is permitted is allowed. 3 Embedded information cannot be Embedded information can be updated; updated, hence the restriction of the this allows the repeated over-writing if repeated overwriting if the embedded embedded electronic information for election information for each card each card. It does not allow for the increase RFID has increased technologies like 4 technologies like surveillance cameras to surveillance cameras to be activated in be activated within employee being in the Conjunction with an employee being in vicinity. their vicinity. It is slower and requires time of sight to RFID is faster and does not require line Function. of sight. 6 It has lower data storage transponder. It has higher data storage. 7 This transponder is bogus, and cannot be The transponder is miniaturized, and can be Incorporated in small items. Incorporate in other items. 5 1.3 What can RFID are used for? RFID tags come in a wide variety of shapes and sizes; they may be encased in a variety of materials. ● Animal tracking tags, inserted beneath the skin, can be rice sized. ● Tags can be screw shaped to identify trees or wooden items. ● Credit-card shaped for use in access applications. ● The anti-theft hard plastic tags attached to merchandise in stores are also RFID tags. ● Heavy duty 120by 100by so millimetre rectangular transponders are used to track Shipping containers, or heavy machinery, trucks, and railroad cars RFID devices have been used for years to identify dogs, for a means of permanent identification. Dog owners had long used tattoos, permanent ink markings, typically on the ears. However, these can fade with age and it may be difficult to get the animal to sit still while you examine him for markings. What have the initial benefits of RFID technology been? RFID technology can deliver benefits in many areas, from tracking work in process to speeding up throughput in a warehouse. Visit RFID journals case studies section to see how companies are using the technology’s potential in manufacturing and other areas. As the technology becomes standardized, it will be used more and more to track goods in the supply chain. The aim is to reduce administrative errors;labour costs associated with scanning bar codes, internal that, errors in shipping goods and overall inventory levels 1.4 RFID limitation Some common problems with RFID are reader collision and tag collision. Reader collision occurs when the signals from two or more readers overlap. The tag is unable to respond to simultaneous queries. Systems must be carefully set up to avoid this problem. Tag collision occurs when many tags are present in a small area; but since the read time is very fast, it is easier for vendors to develop systems that ensure that tags respond one at a time. Unfortunately, not very often in the systems to which consumers are likely to be exposed. Anyone with an appropriately equipped scanner and close access to the RFID device can activate it and read its contents. Obviously, some concerns are greater than others. It someone walks by your bag of books from the bookstore with a 13.56 MHz “sniffer” with an RF filed that will activate the RFID devices in the books you bought, that person can get a complete list of what you just bought that’s certainly an invasion of your privacy, but it could be worse. Another scenario involver a military situation in which the other side scans vehicles going by, looking for tags that only high-ranking officers can have, and for getting accordingly. Companies are more concerned with the increasing use of RFID devices in company badges. An appropriate RF filed will cause the RFID chip in the badge to “spill the beans” to whomever activates it. This information can then be stored and replayed to company scanners, allowing the thief access and your badge is the one that is “credited” with the access. The smallest tags that will likely be used for consumer items don’t have enough computing power to do data encryption to protect your privacy. The most they can do is PINstyle or password based protection. CHAPTER-2 2.1 Basic block diagram LCD Power supply Microcontroller MAX232 RFID Reader Figure 1 Basic block diagram of RFID Expiation Microcontroller It is the Heart of the circuit. We will be using ATMEL’s AT89S52microcontroller. The controller that we will be using is ATMEL’s AT 89s52, which is a 40 pin microcontroller with 32 I/O lines. The controller communicates with the RFID reader & the PC using RS232 protocol for which MAX 232 IC is required. MAX232 Microcontroller communicates with the PC using its inbuilt Serial Port. The voltage levels are 0 & 5 Volts, but for the controller to communicate with the PC we is using RS232 protocolso for converting the CMOS (0-5) voltage levels into RS232 (±12) voltage levels we will be using MAX 232. LCD We will be using 2-Line, 16 characters LCD. This will be used to display the real time, scan successful or not and other such details. Power supply The complete circuit works on 5v this voltage is generated in the power supply section which basically consists of a step down transformer, a rectifier & a voltage regulator. 2.2 PCB layout Figure 2 PCB layout An actual-size, single-side PCB for RFID-based security system is shown in above Fig. And its component layout I bellow Figs. Assemble the circuit on a PCB sit minimises time and assembly errors. Carefully assemble the components and double-check for any overlooked error Figure 3 Component of PCB layout CHAPTER-3 3.1 Circuit diagram Figure 4 Circuit diagram of RFID 3.2Circuit description Fig. 4 shows the circuit of the RFID based security system. The compact circuitry is built around AtmelAT89C52 microcontroller. TheAT89C52 is a low-power, high- performanceCMOS 8-bit microcomputer with 8 dB of Flash programmable and erasable read only memory (PEROM). It has 256bytes of RAM, 32 input/output (I/O) lines, three 16-bit timers/counters, six-vector two-level interrupt architecture, a full-duplex serial port, an onchip oscillator and clock circuitry. The system clock also plays a significant role in operation of the microcontroller. An 11.0592MHz quartz crystal connected to pins 18 and19 provides basic clock to the microcontroller. Power-on reset is provided by the combination of electrolytic capacitor C4 and resistor R1. Switch S1 is used for manual reset. Port pins P2.0through P2.7 of the microcontroller are connected to data port pins D0 through D7 of the LCD, respectively. Port pins P3.7 andP3.6 of the microcontroller are connected to registerselect (RS)and enable (E) pins of the LCD,respectively. Read/write (R/W)pin of the LCD is grounded to enable for write operation. All the data is sent to the LCDin ASCII format for display. Only the commands are sent in hex form. Register-select (RS) signal is used to Distinguish between data (RS=1) and command (RS=0). Present VR1 is used to control the contrast of the LCD.Resistor R6 limits the current through the backlight of the LCD. Port pins P3.0RXD) and P3.1 (TXD) of the microcontrollerare used to interface with theRFID reader. When an authorised person having the tag enters the RF field generated by the RFID reader, RF signal is generated by the RFID reader to transmit energy to the tag and retrieve data from theta. Then the RFID reader communicates through RXD and TXD pins of the microcontroller for further processing. Thus on identifying the authorised person port pin P3.2 goes high, transistorT2 drives into saturation, and relayRL1 energises to open the door for the person. Simultaneously, the LCD shows “access granted” message and port pin P1.7 drives pies buzzer PZ1via transistor T1 for aural indication. If the person is unauthorised, the LCD shows “access denied” and thedoor doesn’t open. LED2 and LED3 show presence of the tag in the RFID reader’s electromagnetic field. To derive the power supply, the230V, 50Hz AC mains is stepped down by transformer X1 to deliver aSecondary output of 15V, 500 mA. The transformer output is rectified by a full-wave rectifier comprising diodesD1 through D4, filtered by capacitorC1 and regulated by ICs 7812 (IC2) and7805 (IC3). Capacitor C2 bypasses the ripples present in the regulated supply.LED1 acts as the power indicator andR2 limits the current through LED1. RFID Reader modual Figure 5RFID ReaderModule Fig.5shows a typical RFID system. In every RFID system, the transponder tags contain unique identifying information. This information can be as little as a single binary bit or a large array of bits representing such things as an identity code, personal medical Information or literally any type of information that can be stored in digital binary format. The RFID transceiver communicates with a passive tag. Passive tags have no power source of their own and instead derive power from the incident electromagnetic field. Commonly, at the heart of each tag is a microchip. Whenthe tag enters the generated RF field, it is able to draw enough power from the field to access its internal memory and transmit its stored information. When the transponder tag draws power in this way, the resultant interaction of the RF fields causes the voltage at the transceiver antenna to drop in value. This effect is utilised by the tag to communicate its information to the reader. The tag is able to control the amount of power drawn from the field and by doing so it can modulate the voltage sensed at the transceiver according to the bit pattern it wishes to transmit. Figure 6 Internals diagram of RFID antenna Antenna. Fig.6shows the internal diagram of a typical RFID antenna. AnRFID antenna consists of a coil withone or more windings and a matching network. It radiates the electromagnetic waves generated by the reader to activate the tag and read/write datafrom itAntennae are the conduits betweenthe tag and the transceiver which control the system’s data acquisition andcommunication. These are available in a variety of shapes and sizes. Often, the antenna is packaged with the transceiver and decoder to become a reader, which can be configured either as a handheld or a fixed-mount device. The reader emits radio waves in range anywhere from 2.54 cm (one inch)to 30 metres or more, depending upon its power output and the radio frequency used. When an RFID tag passes through the electromagnetic zone, itdetects the reader’s activation signal. The reader decodes the data encoded in the tag’s integrated circuit (silicon chip) and the data is passed to the host computer for processing. CHAPTER-4 4.1 Components description AT89c51 Figure 7 AT89c51 The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4Kbytes of Flash programmable and erasable read only memory (PEROM). The devices manufactured using Atmel’s high-density non-volatile memory technology and arecompatible with the industry-standard MCS-51 instruction set and pinout. The on-chipFlash allows the program memory to be reprogrammed in-system or by a conventionalonvolatile memory programmer. By combining a versatile 8-bit CPU with Flashon a monolithic chip, the Atmel AT89C51 is a powerful microcomputer which provides highly-flexible and cost-effective solution to many embedded control applications. The AT89C51provides the following standard features: 4Kbytes of Flash, 128 bytes of RAM, 32 I/O lines, two 16-bittimer/counters, a five vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator and clock circuitryIn addition, the AT89C51 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle Modesto’s 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 Pin diagram Figure 8 PIN diagram of AT89c8051 Pin Description VCC Supply voltage. GND Ground. Port 0 Port 0 is an 8-bit open-drain bi-directional I/O port. As an output port, each pin can sink eight TTL inputs. When 1sare written to port 0 pins, the pins can be used as highimpedanceinputs. Port 0 may also be configured to be the multiplexed low order address/data bus during accesses to external program and data memory. In this mode P0 has internalpull-ups.Port 0 also receives the code bytes during Flash programming, and outputs the code bytes during programverification. Externalpull-up’s are required during program verification Port 1 Port 1 is an 8-bit bi-directional I/O port with internal pull-ups.The Port 1 output buffers can sink/source four TTL inputs. When 1s are written to Port 1 pins they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 1 pins that are externally being pulled low will source current (IIL) because of the internal pull-ups.Port 1 also receives the low-order address bytes during Flash programming and verification. Port 2 Port 2 is an 8-bit bi-directional I/O port with internal pull-ups.The Port 2 output buffers can sink/source four TTL inputs. When 1s are written to Port 2 pins they are pulled high bythe internal pull-ups and can be used as inputs. As inputs, Port 2 pins that are externally being pulled low will source current (IIL) because of the internal pull-ups.Port 2 emits the highorder address byte during fetches from external program memory and during accesses to external data memory that uses 16-bit addresses (MOVX @DPTR). In this application, it uses strong internal pull upwhen emitting 1s. During accesses to external data memory that uses 8bit addresses (MOVX @ RI), Port 2 emits the contents of the P2 Special Function Register. Port 2 also receives the high-order address bits and somecontrol signals during Flash programming and verification Port 3 Port 3 is an 8-bit bi-directional I/O port with internal pullups.The Port 3 output buffers can sink/source four TTL inputs. When 1s are written to Port 3 pins they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will sourcecurrent (IIL) because of the pull-ups.Port 3 also serves the functions of various special features of the AT89C51 as listed below: Port 3 also receives some control signals for Flash programming and verification. RST Reset input. A high on this pin for two machine cycles while the oscillator is running resets the device. ALE Address Latch Enable output pulse for latching the low byte of the address during accesses to external memory. This pin is also the program pulse input (PROG) during Flashprogramming. In normal operation ALE is emitted at a constant rate of 1/6the oscillator frequency, and may be used for external timing or clocking purposes. Note, however, that one ALEpulse is skipped during each access to external DataMemory. If desired, ALE operation can be disabled by setting bit 0 ofSFR location 8EH. With the bit set, ALE is active only during MOVX or MOVC instruction. Otherwise, the pin isweakly pulled high. Setting the ALE-disable bit has noeffect if the microcontroller is in external execution mode. PSEN Program Store Enable is the read strobe to external programmemory.When the AT89C51 is executing code from external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped duringeach access to external data memory. EA ExternalAccess Enable. EA must be strapped to GND in order to enable the device to fetch code from external programmemory locations starting at 0000H up to FFFFH.Note, however, that if lock bit 1 is programmed, EA will be internally latched on reset. A should be strapped to VCC for internal programexecutions. This pin also receives the 12-volt programming enable voltage (VPP) during Flash programming, for parts that require12-volt VPP. XTAL1 Input to the inverting oscillator amplifier and input to the internal clock operating circuit. XTAL2 Output from the inverting oscillator amplifier. MAX232 Figure 9 MAX232 The MAX232 IC is used to convert the TTL/CMOS logic levels to RS232 logic levels during serial communication of microcontrollers with PC. The controller operates at TTL logic level (0-5V) whereas the serial communication in PC works on RS232 standards (-25 V to + 25V). This makes it difficult to establish a direct link between them to communicate with each other. The intermediate link is provided through MAX232. It is a dual driver/receiver that includes a capacitive voltage generator to supply RS232 voltage levels from a single 5V supply. Each receiver converts RS232 inputs to 5V TTL/CMOS levels. These receivers (R1& R2) can accept ±30V inputs. The drivers (T1& T2), also called transmitters, convert the TTL/CMOS input level into RS232 level. Figure 10 Pin diagram of MAX232 The transmitters take input from controller’s serial transmission pin and send the output to RS232’s receiver. The receivers, on the other hand, take input from transmission pin of RS232 serial port and give serial output to microcontroller’s receiver pin. MAX232 needs four external capacitors whose value ranges from 1µF to 22µF. LCD display Figure 11 LCD display LCD (Liquid Crystal Display) screen is an electronic display module and find a wide range of applications. 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. A 16x2 LCD means it can display 16 characters per line and there are 2 such lines. In this LCD each character is displayed in 5x7 pixel matrix. This LCD has two registers, namely, Command and Data. The command register stores the command instructions given to the LCD. A command is an instruction given to LCD to do a predefined task like initializing it, clearing its screen, setting the cursor position, controlling display etc. The data register stores the data to be displayed on the LCD. The data is the ASCII value of the character to be displayed on the LCD. Single pin connector Figure 12 Single pin connector They allow me to connect any port pin of the microcontroller to any input or output pin of any interface section on our boards. These connectors comes handy when you have task to connect microcontroller's 3 different pins located at a distance a 3 pin connector of some interface (e.g. RS RW EN lines between microcontroller and LCD section on EEDT5.0 board or any similar design).I was using these connectors for many months now, and thought of sharing them with you. Thus simply added these connectors (female to female single pin connecting cables!!) to our product catalo. They are low cost and will make your life simple. Use these single pin connectors for logic level connections as they are designed to handle few mA current (less than 100mA).Standard length of these connectors is 30cm Pull-up resistor Pull-up resistors are used in electronic logic circuits to ensure that inputs to logic systems settle at expected logic levels if external devices are disconnected or impedance. They may also be used at the interface between two different types of logic devices, possibly operating at different power supply voltages. Figure 13 Pull-up resistor When the switch is open the voltage of the gate input is pulled up to the level of Vin. When the switch is closed, the input voltage at the gate goes to ground. A pull-up resistor weakly "pulls" the voltage of the wire it is connected to towards its voltage source level when the other components on the line are inactive. When all other connections on the line are inactive, they are high-impedance and act like they are disconnected. Since the other components act as though they are disconnected, the circuit acts as though it is disconnected, and the pull-up resistor brings the wire up to the high logic level. When another component on the line goes active, it will override the high logic level set by the pull-up resistor. The pull-up resistor assures that the wire is at a defined logic level even if no active devices are connected to it. A pull-down resistor works in the same way but is connected to ground. It holds the logic signal near zero volts when no other active device is connected. LED A light-emitting diode (LED) is a semiconductor light source. LEDs are used as indicator lamps in many devices and are increasingly used for other lighting. Introduced as a practical electronic component in 1962, early LEDs emitted low-intensity red light, but modern versions are available across the visible, ultraviolet, and infrared wavelengths, with very high brightness. Figure 14 LED When a light-emitting diode is forward-biased (switched on), electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect is called electroluminescence and the colour of the light (corresponding to the energy of the photon) is determined by the energy gap of the semiconductor. LEDs are often small in area (less than 1 mm2), and integrated optical components may be used to shape its radiation pattern. LEDs present many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved robustness, smaller size, and faster switching. LEDs powerful enough for room lighting are relatively expensive and require more precise current and heat management than compact fluorescent lamp sources of comparable output. Light-emitting diodes are used in applications as diverse as replacements for aviation lighting, automotive lighting (in particular brake lamps, turn signals, and indicators) as well as in traffic signals. LEDs have allowed new text, video displays, and sensors to be developed, while their high switching rates are also useful in advanced communications technology. Infrared LEDs are also used in the remote control units of many commercial products including televisions, DVD players, and other domestic appliances RFID Tag Figure 15 RFID tag An RFID Tag is an electronic circuit and one or more antennas that use RF waves to communicate an identifier which allows it be differentiated from other electronic circuits. RFID tags are attached to, affixed to, or embedded in, inanimate or animate objects for the purpose of unique identification. Since the tag is what is identified, an association must be created between the tag and the object. The word "tag" is commonly used because the electronic circuit is typically designed for the purpose of being associated with something else. RFID tags are often used to determine the approximate location of the object to which it is associated. RFID tags can be categorized by the method in which is it powered. The most common terms used for differentiation in this manner are: Passive RFID Tags Battery-Assisted Passive (BAP) RFID Tags or Semi-passive RFID tags Active RFID Tags The parallax RFID reader module can be integrated into any design using only four connections. Use the following circuit for connecting the parallax RFID reader module to the BASIC stamp microcontroller. Pin Pin name Type Function 1 VCC Power System power,+5v DC input 2 ENABLE Input Module enable pin active LOW DIGITAL input Bring this pin LOW to enable the RFID reader and activate the antenna 3 SOUT Output Serial out TTL-level interface 2400bps,8 data bits no pity,1 stop bit 4 GND Ground System ground connect to power supply is ground terminal Diode Figure 16 Diode In electronics, a diode is a type of two-terminal electronic component with nonlinear resistance and conductance (i.e., a nonlinear current–voltage characteristic), distinguishing it from components such as two-terminal linear resistors which obey Ohm's law. A semiconductor diode, the most common type today, is a crystalline piece of semiconductor material connected to two electrical terminals. A vacuum tube diode (now rarely used except in some high-power technologies) is a vacuum tube with two electrodes: a plate and a cathode. The most common function of a diode is to allow an electric current to pass in one direction (called the diode's forward direction), while blocking current in the opposite direction (the reverse direction). Thus, the diode can be thought of as an electronic version of a check valve. This unidirectional behaviour is called rectification, and is used to convert alternating current to direct current, and to extract modulation from radio signals in radio receivers—these diodes are forms of rectifiers. However, diodes can have more complicated behaviour than this simple on–off action. Semiconductor diodes do not begin conducting electricity until a certain threshold voltage is present in the forward direction (a state in which the diode is said to be forwardbiased). The voltage drop across a forward-biased diode varies only a little with the current, and is a function of temperature; this effect can be used as a temperature sensor or voltage reference. Semiconductor diodes' nonlinear current–voltage characteristic can be tailored by varying the semiconductor materials and introducing impurities into (doping) the materials. These are exploited in special purpose diodes that perform many different functions. For example, diodes are used to regulate voltage (Zenger diodes), to protect circuits from high voltage surges (avalanche diodes), to electronically tune radio and TV receivers (varactor diodes), to generate radio frequency oscillations (tunnel diodes, Gunn diodes, IMPATT diodes), and to produce light (light emitting diodes). Tunnel diodes exhibit negative resistance, which makes them useful in some types of circuits. Diodes were the first semiconductor electronic devices. The discovery of crystals' rectifying abilities was made by German physicist Ferdinand Braun in 1874. The first semiconductor diodes, called cat's whisker diodes, developed around 1906, were made of mineral crystals such as galena. Today most diodes are made of silicon, but other semiconductors such as germanium are sometimes used. capacitor Figure 17 Capacitor A capacitor (formerly known as condenser) is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric (insulator); for example, one common construction consists of metal foils separated by a thin layer of insulating film. Capacitors are widely used as parts of electrical circuits in many common electrical devices. When there is a potential difference (voltage) across the conductors, a static electric field develops across the dielectric, causing positive charge to collect on one plate and negative charge on the other plate. Energy is stored in the electrostatic field. An ideal capacitor is characterized by a single constant value, capacitance, measured in farads. This is the ratio of the electric charge on each conductor to the potential difference between them. The capacitance is greatest when there is a narrow separation between large areas of conductor; hence capacitor conductors are often called "plates," referring to an early means of construction. In practice, the dielectric between the plates passes a small amount of leakage current and also has an electric field strength limit, resulting in a breakdown voltage, while the conductors and leads introduce an undesired inductance and resistance. Capacitors are widely used in electronic circuits for blocking direct current while allowing alternating current to pass, in filter networks, for smoothing the output of power supplies, in the resonant circuits that tune radios to particular frequencies and for many other purposes. The simplest capacitor consists of two parallel conductive plates separated by a dielectric with permittivity ε (such as air). The model may also be used to make qualitative predictions for other device geometries. The plates are considered to extend uniformly over an area A and a charge density ±ρ = ±Q/A exists on their surface. Assuming that the width of the plates is much greater than their separation d, the electric field near the centre of the device will be uniform with the magnitude E = ρ/ε. The voltage is defined as the line integral of the electric field between the plates. Solving this for C = Q/V reveals that capacitance increases with area and decreases with separation The capacitance is therefore greatest in devices made from materials with a high permittivity, large plate area, and small distance between plates. We see that the maximum energy is a function of dielectric volume, permittivity, and dielectric strength per distance. So increasing the plate area while decreasing the separation between the plates while maintaining the same volume has no change on the amount of energy the capacitor can store. Care must be taken when increasing the plate separation so that the above assumption of the distance between plates being much smaller than the area of the plates is still valid for these equations to be accurate. CHAPTER-5 5.1 Coding #include<reg51.h> #include<stdio.h> #include<string.h> Sfr lcd_data_pin=0xA0; //P2 port sbit rs=P1^0; //Register select sbit rw=P1^1; //Read/Write sbit en=P1^2; //Enable pin sbit led=P0^0; unsigned char card_id[13]; void delay(unsigned int count) //Function to provide delay { int i,j; for(i=0;i<count;i++) for(j=0;j<1275;j++); } void lcd_command(unsigned char comm) //Lcd command funtion { lcd_data_pin=comm; en=1; rs=0; rw=0; delay(1); en=0; } void lcd_data(unsigned char disp) //Lcd data function { lcd_data_pin=disp; en=1; rs=1; rw=0; delay(1); en=0; } lcd_string(unsigned char *disp) //Function to send string { int x; for(x=0;disp[x]!=0;x++) { lcd_data(disp[x]); } } void lcd_ini() { lcd_command(0x38); delay(5); lcd_command(0x0F); delay(5); lcd_command(0x80); delay(5); //Function to initialize the LCD } void recieve() //Function to recieve data serialy from RS232 { unsigned char k; for(k=0;k<12;k++) { while(RI==0); card_id[k]=SBUF; RI=0; } } void main() { // int l; TMOD=0x20; //Enable Timer 1 TH1=0XFD; SCON=0x50; TR1=1; // Triggering Timer 1 lcd_ini(); P3=0xff; while(1) { delay(200); lcd_command(0x81); lcd_string("WELCOME TO RFID"); delay(200); lcd_command(0xC1);lcd_string("BASED SYSTEM"); delay(200); lcd_command(0x01); delay(200); lcd_command(0x81); lcd_string("PLZ SCAN YOUR"); delay(200); lcd_command(0xC1); lcd_string("CARD "); recieve(); delay(100); if(strcmp(card_id,"4E0070297067")==0) { delay(100); lcd_command(0x01); delay(200); lcd_command(0x81); lcd_string("THANK YOU"); delay(200); led=~led; delay(1000); } else { lcd_command(0x01); delay(200); lcd_command(0x81); lcd_string("YOU ARE NOT"); delay(200); lcd_command(0xC1); lcd_string("AUTHO PERSON"); delay(200); lcd_command(0x01); delay(200); lcd_command(0x81); lcd_string("SCAN YOUR ID"); delay(200); lcd_command(0xC1); lcd_string("AGAIN"); delay(200); } } } Advantages RFID tags have read/write memory capability More data can be stored in an RFID tag RFID tags have a longer read range Low cost solution With little software modification extensible to any other microcontrollers Future scope A hex key pad can be interfaced to microcontroller board by which user can enter his password then only the lock can be opened. This ensures even if someone has card then also without the password he can’t get access. Connection to PC and development of PC side software to read from microcontroller Implementing the security systems with different levels by using different types of misfire cards. Cryptanalysis of the link between the card and reader. Study of other RFID techniques for better service and security. Interfacing the system with a GSM so that data can be transmitted through messages. Other application Automotive Education & Libraries Enterprise Food service distribution Government Health care Hospitality Law enforcement Life science Logistics Manufacturing Postal/parcel Public spaces Retail Security Transportation Conclusion RFID technology is growing rapidly and widely. Already RFID environment is implemented everywhere. In the contrary in convenient of RFID, there are threats compromising security and privacy. The moreRFID is used in daily life and provide important personal information, the bigger security and privacy issues are increased. Currently many researches related about RFID security and privacy are being progressed. In order to protect personal information and provide safe RFID environment, the more researches about RFID privacy and security should be done Reference RFID security and privacy: a research survey, air juels,RSA laboratories Electronics for you www.EFYMAG.com www.rfidsurvival.com www.rsasecurity.com