Keypad security with 8051 Microcontroller

This project interfaces famous Microcontroller AT89C51 with LCD 16×2 with 3×4 Keypad. This project asks the user to enter password to unlock the lock or light up the LED. Password security via keypad can be very productive you can just put a security lock outside your door and use a servo motor to unlock the door if the user enters a correct password. However, in this project we use a simple LED if the user enters a correct password LED will glow else not. To see how to interface a simple keypad with LCD using AT89C51 please visit here....

KeyPad Interface with AT89C51 and LCD

This simple project tells you how to interface 4×3 phone keypad with famous 8051 Microcontroller AT89C51 and displays the numbers on LCD 16×2 If you want to know how to interface LCD with 8051 Please visit here. Keypad acts as a Matrix switch as shown below: These switch matrix is a combination of switches in rows and columns. Now if we want to detect what switch is pressed we will scan rows and columns. Lets say that we put all rows of the matrix on a digital HIGH by using Microcontroller and then scan each column for a pressed key....