In the present scenario, security access control systems are of different types. It includes security system using keypad, barcode systems and magnetic card systems. In both of these accessing systems, swiping of card is necessary for verification of the card. There is a chance of occurring error. Error may occur due to speed of the swiping and angle of the swiping.
In keypad system, a password or a personal identification number (PIN) is set in the microcontroller. The password may have numbers or characters. By typing that particular password one can get access to the system. But there are many disadvantages in using only keypad access.
Anyone who knows the password can access the system.
Possibility of hacking is high.
Ones you forget the password the all system needs to be reset.
There is a possibility of tampering with the keypad.
Using RFID, we can overcome these limitations. In our system there is no need for swiping. So the error probability is very low compared to other systems. Thus the system is more reliable. It consists of an RFID reader and RFID tags.
A person who needs to access a door must have an RFID tag with him. The tag is shown to the reader when a ‘READY’ message is displayed on the LCD. The microcontroller compares each digit of number received from the reader and set a flag. For the demonstration we divided the cards in to three categories. The first one is “OWNER”, second one “MODERATOR” and third one is “GUEST”. All other cards are invalid .This is done only for demonstration purpose and in actual practice we can divide the cards to any number of categories or in any of these categories depending on the system requirement. In our system the card belonging to the ”OWNER” requires no passwords. He gets direct access by showing the card. When this type of card is shown the message “OWNER U R WELCOME’ is displayed on the LCD and this door is opened for him. The one, who possess the card in the category “GUEST”, requires a uniques password for accessing the secured area. On showing his card, the message “ENTER UR PASWD” is displayed on the LCD. On giving correct password, the message, the message “GUEST U R WELCOME” is displayed and he gets access. When the card of the group “MODERATOR” is shown, the message “ENTER UR PASSW” is displayed. Apart from the GUEST, moderators have different passwords by which they can access the door. When the right password is given the message “MODERATOR U R WELCOME” is displayed on the LCD. In all the conditions, when the access is granted, the relay circuit is activated.
Here an 89c52 microcontroller is used. As this microcontroller has an internal ROM there is no need for an external ROM. Display used is a 16 X 2 line display capable of displaying alphanumeric characters. The keypad used is a 3 X 4 matrix type. The relay used is a 5V. A stepper motor is also used for opening the door.
BLOCK DIAGRAM
BLOCK DIAGRAM DESCRIPTION
MICROCONTROLLERS
Here an 89c52 microcontroller is used. As this microcontroller has an internal ROM there is no need for an external ROM. It has an internal Rom of 8k which is sufficient for the inclusion of the program requiring for this project. If the program is greater, the there is an additional facility to keep an external ROM.
RFID Reader and Tags
RFID reader module continuously produces radio frequency signals. These tags are passive ones and it contains a embedded circuit and a coil. When the tag comes near the field produced by the reader, it gets activated. The data present in the card is send to the reader. The reader gives the details of the card that is a 26 bit data as output in both Weigand format and RS485 format.
SRAM
The static RAM used in HM62256 made by Hitachi. It has a memory of 32k word X 8 bit. SRAM can be replaced with an NVRAM of same pin configuration for the further development of the project.
KEYBOARD
We use matrix type of keyboard here. For entering the password, we require only digits; so we use a 3X4 matrix keyboard for this purpose.
RELAY
The relay is powered up when the tags and passwords satisfy the required condition. This relay can be connected to a magnetic latch or some other devices to control and access. The relay used here is a 5V relay.
DISPLAY
The display used here is a 16 characterX2 line LCD display. It can display alphanumeric characters. It display various commands such as “OWNER U R WELCOME”,”WRONG PASWD”,”NO ACCESS” etc.
RADIO FREQUENCY IDENTIFICATION (RFID)
RFID – radio frequency identification- is a technology that is rapidly crossing from being expensive and experimental to universal usefulness. The basic concept is quite simple.: attach small coiled radio antenna to a microchip and implant it in any thing that needs to be read,scanned,monitored, warehoused or altered. Radio frequency identification (RFID) is a wireless communication technology with advanced features ideal for making contact less payments, item tracking, and automatic data collector.
Chip tags are usually made to work at specific frequencies which are license free. The tolerated power levels and regulations for these vary from country to country. For ex, the maximum permitted legal power level( the power level at which interrogator is set at) for 2.45 GHZ in the US is 100 time the higher than the Europe. This creates a huge difference in the read range- a 1 meter range in the US may only be a centimeter range in Europe, all else being equal! There fore, much work still needs to be done to balance these regulatory issues worldwide, though there is some progress. Similar to barcode technology RFID has several advantages including more data capacity (up to 1`6k bits), scanning multiple tags simultaneously tag data is read and write, and no line of sight is required between tags and reader.
RFID Tags
RFID store their memory without a battery. They can be made very small and attached to anything that needs a memory or an ID number. FID tags come in many shapes and sizes such as thin disks, credit cards or paper labels called smart labels. There are three types of RFID tags- Active, Passive, Semi-passive. An active RFID tags have a battery which is used to run the microchip circuitry and to broadcast a signal to a reader. A passive RFID tag draws power from field created by the reader and uses it to power the microchip’s circuits. Semi-passive tags use a battery to run the chip circuitry but communicate by drawing power from the reader
RFID Readers
RFID Readers can read from and write to RFID tags without contact, even through walls. The read range is the maximum communication distance between tag and reader. Read rage can vary from centimeters to several meters, depending on the tags and readers used. Whether portable or fixed- position, readers can read and write multiple tags at one time.
HOW RFID WORKS
It is a generic term or technologies that use radio wave to automatically identify people or objects. There are several methods of identification. But the most common is to store a serial number that identifies a person or object, and perhaps other informations on a microchip that is attached to an antenna (the chip and antenna together are called an RFID transponder or an RFID tag). An RFID system that consists of that tag, which is made up of a microchip made of antenna, and an interrogator or a reader with an antenna. The antenna enables the chip to transmit the identification information to the reader, the reader sends out electromagnetic waves. The e tag antenna is tuned to receive this waves.. The chip then modulates the wave that the tag sends back to the reader. The reader converts these radio waves reflected back from the RFID tag in top digital information that can be passed on to computers that make use of it.
When the RFID tag is activated by a reader device, it transmits information from the chip to a centre computer system which can be about 2kbyte of information that can held on a single chip.
Inside an RFID tag is a microchip connected to an antenna. The e chip can store modest amount of information up to about 2 Kbits. The tags come in a variety of form factors and can be attached to anything. RFID tags are often used to store a simple identification number in more sophisticated methods tag can function as a portable traveling data base for the item to which it is attached.
The RFID readers control the wireless reading and writing of information stored on an RFID tag. The RFID reader generates an RF field around its antenna. The RF field gives the tag power, a clock, and a way to transfer the data to the reader. The tag modulates the readers RF field and the reader can detect this. Similarly the reader turns the RF field on and off in the right sequence in order to write the tag.
A LOOK AT RFID TECHNOLOGY
“RFID at present appears to be an evolutionary rather than revolutionary technology?” as Prof Charley Fine said.
Radio Frequency identification (RFID) is a method of remotely storing and retrieving data using devices called RFID tags. The basic technology has been around for several years and it is only recently that- driven by the standardization activities and other industry initiatives- The RFID has started to gain visibility.
RFID can be broadly categorized as an ‘e-tagging’ technology. At the fundamental level, RFID can be seen as evolution from barcodes. Barcodes are the simplest forms of tagging. Using barcodes, information about the item can be captured using optical barcode scanners. RFID enables passive object tagging using RF (Radio Frequency) sensing as opposed to optical sensing used in the case of barcodes.
ADVANTAGES
• RFID technology permits no line of sight reading.
• Robustness and reliability under difficult environmental conditions.
These tags can be read through water, snow, concrete, bricks, plastics, wood, and most non-metallic materials
• Available in a wide variety of physical forms, shapes, sizes and protective housings.
• RFID tags can be read at very high speeds.
In most cases the response time is less than 100ms.
• Difficulty in duplicating, offers a high degree of security.
• RFID reder can read multiple tags simultaneously and instantly.
• RFID tags can store a lot more information than bar codes.
DISADVANTAGES
• Cost
RFID solutions cost much higher than the conventional barcodes. A large fraction of its cost lies in the software infrastructure and the enterprise application and integration.
• Lack of standardization
Standardization has not been provided across many fronts, ranging from the different data formats used to interpretability between RFID readers and tags from different vendors to interference between RFID products from different manufacturers.
• Used mainly for short distance applications
Around 90% of all applications use less than 10cm distance between reader and tag – “each additional cm costs money”.
• Higher frequencies – even more problems:
- Multipath propagation
- Reflections
- Absorption (water, metal)
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