4x4 key pad programing - please help

the probs occur in keypad due to keydebouncing. If you want to do it properly, use 74922 or 74923 key encoders with keypad to avoid it. Refer this book also
MY EXPERIENCE IN PARALLEL PORT INTERFACING
connect data out(4 bit in case of 922) to the data pins of the uC and DAta available to the separate pin. When DA=1 then key is pressed and no problems occur to u. But the cost of 922 is high. Don't go for other keyencoders like 74148 bcz they don't have keydebounce mask. The proper capacitance should be applied to 922 to mask keydebounce and tht is explained in tht book.

Bibin John
www.bibinjohn.tk

Atmel Version

Hi,
I've used this code. Works well. There are some nice routines in this code to keep in your personal code bank to be used on other project etc.
If your using another uP just convert the code across.
https://www.serasidis.gr/circuits/lcd_keys/lcd_keys.htm

The rest on his site has some nice project too.
You will never guess how I found it. GOOGLE!

Cheers
Bones

Key Pad Programming

I want to make a security project using 89c51 microcontroller.


Anyone can help me for the code of this security project using Keypad and a LCD.





Help me