Preface: – Presently there are many types of cards available such as punch cards, magnetic cards, optical cards but all are having the disadvantage of performance degradation as we use them.
Other disadvantages are: –
- They can not store much information.
- They can not be read from a distance.
- They lose their data if placed under magnetic field or even on scratching.
- There is no security to protect card data whereas in our card this is achieved with the provision of passwords.
- There is no Re-Writable memory for temporary data storage such as railway reservation ticket.
The above-mentioned shortcomings are technical but there are user related problems also when one needs to handle a large number of cards at a time to obtain diverse information (Atm, Credit card, License, Voter Id. etc.). The user is highly inconvenienced as he is required to change over the cards frequently, so we have designed a card which combines information contained in a variety of cards. Since data is transferred using IR sensors so in many applications we can identify the user from a distance. We can also lock the data stored in card by using various passwords. Card can also store specific data in RAM for temporary use such as railway reservation, air bookings etc. we can also use the cards in automatic doors fitted with sensors which read the card from some distance and open the door only for authorized card holders.
1. Card Unit: –
IR Sensors: – We are using here the infrared light as communication medium because of its low cost and better reception in short range communication. To make the receiver perform better it is designed to recognize the switching IR light of particular wavelength.
The wave length and switching frequency can be taken from the manufacturers data sheets
Buffer Amplifier: – The O\P of sensor does not have the current capacity to drive the microcontroller hence we use the buffer amplifier between sensor and micro controller.
Buffer Amp 2: – This section provides the current gain to signals coming from microcontroller.
Astable M.V.: – It generates the switching waveform to switch the IR LED on & off the frequency of the M.V. depends upon the sensor used.
Micro controller: – This is the part of card which stores the data in its EEPROM & also performs all the operations required for testing the incoming data & to decide the response of received data. It also controls the mode of serial communication and speed of communication.
2. PC Unit: –
For the pc unit all the blocks are same but instead of using microcontroller we use serial port of pc which follows the RS232 standard hence we use a Level Converter between port and Buffer Amp.
The first level converter converts the TTL signals in to RS232 signals & second level converter converts the RS232 signals to TTL signals. The conversion is necessary because the sensors & M.V. works on TTL logic.
3. Door unit: –
Here we implemented one utility of the card by opening the cabin door (in office) automatically as the authorized person come up to a certain distance from door, by reading his or her card from distance.
Now if the cards data does not match with door unit it sends the persons card number to PC & ask to open the door if operator press Y the door unit will open the gate.
To complete the door unit we require combining the following section as shown in block diagram.
Now we see that all the sections as same as we have discussed in previous blocks except that Relay & Beeper section. So we will discuss only this section. The door unit performs the two work one send data to call the specific data from card & read data from card through sensor. Now if persons card no does not match with unit it sends the pulses the beeper unit which produce the intermittent beep sound to indicate that door is not opened.