So after learning almost all major concepts, its time to implement some of them together and create something that actually work. Here is a simple project called "Digital Code Lock" using our very well known AT89S52, a 4x3 Matrix Keypad and one 20x4 Alphanumeric LCD. We have covered all the basic concepts of interfacing LCD, Keypad etc. Now lets dig into depth of this...
This project is simply the one very well known password protected electronic security system. This system is implemented in such a way that it asks user for authorize himself before getting a green signal to enter into somewhere. User must enter a right password to authorize himself.
System has two kind of password security. A generel user password which is of length 5 digits and a master password which has a length of 10 digits. Password will be numeric only as we are going to program our keypad as numeric keypad only.
Firstly user will try to enter the correct 5 digit password. System will give total of 3 chances to each user to enter the correct 5 digit password, if user doesn't enter correct 5 digit password in 3 chances, system will ask the user to enter the 10 digit master password. If user fails to enter correct master password, our system consider current user as an unauthorized person.
In case of 5 digit password if some user enters password length more that 5 digits system will warn the user by message "password too long; try again" this will also consume one chance out of three.
We have used 20x4 Alphanumeric LCD here, it has some additional commands ---
Goto first line -- 80h
Goto second line-- C0h
Goto Third line -- 94h
Goto Fourth Line-- D4h
Click here to see the source code