8051 4 Digit Electronic Code Lock with LCD and Keypad


It’s an example of 8051 4 Digit Electronic Code Lock with LCD and Keypad.

Circuit Diagram


This is a simple example of electronic code lock based on 8051 microcontroller. This example project also describes how can we interface 16×2 LCD and keypad. Simple Telephone keypad is used for this project. Initially when system is started “Enter Password ” is displayed on 1st row and user enters password and at each key press a ‘*’ is displayed on screen. This password is of 4 digit length. If after entering 4 digits password matches with predefined password in the program code then system activates the lock relay attached at pin # 0 of port P2 means opens lock and displays user a message that lock is opened. Now on pressing ‘*’ key user can enable lock again. If password is incorrect then system shows invalid password message and does not open the lock. Password for the lock defined in the code is “1234”. If user enters a wrong key and wants to enter password again from start then user can press ‘*’ to re-enter password in the middle.

For detail of LCD interfacing please see 8051 To 16×2 LCD Interfaing.

For basic operation & components used in an 8051 based microcontroller based systems see
8051 Basic LED Flasher.

Free Downloads

HD44780 Datasheet

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