SMARTCARD BASED DOOR ACCESS SYSTEM USING LCD
SMARTCARD BASED DOOR.pptx
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Here is the microcontroller-based Smartcard based door access system that can be used where accessing of door or any other electrical device, can open using a smart card on inserting the card user’s data is read by the microcontroller which will process the data the card is an EPROM IC.
The system is small, simple, cost-effective and good for smartcard based door. Smartcard is one of the latest additions to the world of information technology . It is connected to the LCD & KEYPAD. Smartcard may have up to 512 kb of EEPROM.Also this circuit operation is easily understand and easily runs circuit.
Whole project can be divided into 7 blocks. They are:
Smartcard & smartcard Reader.
16x2 LCD INTERFACE
Pin RC.0-to-RC.5 is connected with (16x2) LCD display. Microcontroller sends the data signals through pin no. RC.0-to-RC.3. this pin no. RC.0 to RC.3 is connected to pin no. 14 to11 of LCD display.
Control signal are send by microcontroller through pin no.RC.4 and RC.5 to LCD via pin no. 4 & 6 respectively. Pin no 3 of the LCD is used to control the contrast by using preset PR1.
Pin no. 1, 5 & 15 of LCD are normally connected to ground (GND). And pin no. 16 is normally connected to +5V (VCC) which supplies power to display.
Buzzer interface is used to audible indication for valid user and error situation and Alarm mode. A buzzer connected to the micro controller pin no. RC.7 via driver transistor BC547.
If we connect buzzer directly to pin no. RC.7 than buzzer will have input of only +5V at a current of around 0.6mA and to drive the buzzer it requires 12 volts at a current of around 50ma, which can’t be provided by the micro controller. So by keeping the driver transistor in common emitter configuration i.e. by connecting the pin no. RC.7 to base & buzzer to collector & another pin of buzzer to unregulated power supply of 12V (VDD) the buzzer can be operated.
It is used for opening and closing of door. A Single-Pole-Double-Throw (SPDT) relay is connected to the micro controller pin no. RC.6 via driver transistor of BC547.
If we connect Relay directly to pin no. RC.6 than relay will have input of only +5V at a current of around 0.6mA and to drive the relay it requires 12 volts at a current of around 100ma, which can’t be provided by the micro controller. So by keeping the driver transistor in common emitter configuration i.e. by connecting the pin no. RC.6 to base & relay to collector & another pin of relay to unregulated power supply of 12V (VDD), the relay can be operated.
Now, when pin no. RC.6 pin will go high, the driver transistor will conduct and so current will flow from VDD to ground via LED L2 & so L2 LED will glow. And current will also flow from relay coil thus relay will operate.
Diode D6 is the standard diode on a 5 mechanical relay to prevent back EMF from damaging driver transistor Q2 when the relay releases it. LED L2 glow indicates that relay on.