Basic Operation of password based lock :
An electronic lock is a device which has an electronic
control assembly attached to it. They are provided with an access
control system. This system allows the user to unlock the door with a password.
The password is entered by making use of a keypad. The user can also set his
password to ensure better protection. The major components include a keypad ,
LCD and the controller AT89C51 which belongs to the 8051 series of
microcontrollers. First system wants a predefined password and LCD will show the
message “ ENTER PASSWORD”. The length of the predefined password is four letter.
If the user’s given password matched with the predefined password then only the
lock will open. If not matched then LCD will show “SORRY”. If user will attempt
to give the password three times simultaneously then the microcontroller will
stop the access of the user for some times.
We have used port 1 for data bus of LCD, port 2.0-2.2 for controlling the LCD, port 3.5-3.7 for the column of keypad, port 2.3-2.6 for the row of key pad and port 0.6 and 0.7 is used for LED on/off. All the ports except port 3.5-3.7 is output port. We have used the oscillator of 11.0592 MH.