Security is a prime concern in our day-today life. Everyone wants to be as much secure as possible. An access control for doors forms a vital link in a security chain. The microcontroller based digital lock for Doors is an access control system that allows only authorized persons to access a restricted area.
An electronic lock or digital 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 device 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 PIC16F877A. This article describes the making of an electronic code lock using the 16F877A microcontroller.
The system is fully controlled by the 8 bit microcontroller 16F877A which has a 8Kbytes of ROM for the program memory. The password is stored in the EPROM so that we can change it at any time. The system has a Keypad by which the password can be entered through it. When the entered password equals with the password stored in the memory then the relay gets on and so that the door is opened.
The code is built in a modular style to allow a user to find ways to modify project. In start the D Lock programs loads with a default code of "2345" format is *2345# which can be enter to unlock the door, the code cam be change by entering the master code in the format *23455#new 4 digit code. In this program i only display the result on LCD and lock will be placed at PORTA bit 0 where i put led for simulation.
A 4x3 matrix keypad and a 16x2 LCD have been used here. Keypad and LCD are very commonly used input & output devices, respectively. The password is stored in the system EEPROM.
While unlocking, if the entered password from keypad matches with the stored password, then the lock opens and a message is displayed on LCD. Also an output pin is made high to be used for further purpose..
As the program starts, wait for 5sec and press * string ‘Enter Password’ is displayed on LCD. The keypad is scanned for pressed digits one by one. Every time, row and column of the key pressed is detected and is displayed on LCD. After the four digits are entered, the user should press # to Confirm Password and again the input is taken through LCD. If the passwords do not match, a message is displayed to indicate ‘Access Denied’ otherwise the ‘Access Granted’ message.
Update 28-8-20131. Here two circuit are provided, the smaller one works only for
simulation and the larger one works only in real world( Problem
with Pull Down resistors)
2. Due to frequent Requests I have Uploaded the HEX(8Mhz Crystal) file of these project in Our Facebook Group-Click Here