4x4 keypad on mini2440

Hello,
I want to interface 4x4 keypad with mini2440 (running linux) using GPIO..
any ideas??

Hey,
I want this too...!
Please give suggestions...

This certainly can be done. At least I did it on WinCE.

But how? I need it for linux

Do you mean implement it inside an application or actually make it function
like a keyboard in that it will send the digits which are being depressed?

I mean "actually make it function like a keyboard in that it will send the
digits which are being pressed"

and that too using GPIOs

The keypad you are referring to needs to be scanned for key presses.

In terms of making it function like a keyboard you'll need to look at the
existing keyboard drivers in /linux-2.6.32.2/drivers/input/keyboard

I suspect that its not going to allow you to perform the actual scanning
for key presses but I haven't looked at the existing keyboard drivers to
see if this would be possible.

If not, a recommendation would perhaps be to use some simple external micro
controller such as those from www.microchip.com to send key pressed
information through to the mini2440 when ever they are depressed.

A simpler implementation would be to use a micro-controller to send key
presses through to one of the serial ports - that way you can perhaps
modify the serial keyboard driver.

I do not yet have one of these mini2440 boards so I cannot experiment with
it. If I can figure out whether it meets my other requirements I will
gladly help to get a 4x4 working.

Do you have the GPIO dricers?. If so, you can set 4 IO's as inputs and 4
IO's as outputs. You connect the first 4 lines to the columns, and the
other 4 to the rows. The inputs must have pull aup resistors.

The rutine is simple. You set 3 of the output lines in high, and 1 line in
low. Depending on the values of all the lines (inputs and outputs) you
determine if a key has been preseed. You must secuencially rotate the low
level for each one of the 4 output pins, and the read the values.

It is the same you do when working with microcontrollers.

That is all.

Try:
http://www.avrfreaks.net/index.php?name=PNphpBB2&file=search
and put in keypad and sift thru 753 hits.

Yes, I have GPIO drivers enabled..
I will surely try this..
Thank you for all the ideas..

hello all,

i implemented the keyboard with GPIOs but but it seems that key detection
using this keyboard is very slow you can say 30-40 % only (3-4 keys get
detect out of 10 key press ).

so how can we increase the key detection speed ??


regards ,
sagar

How to find the spare gpio pins, which can be possible
to connect an external device(like 4x4 keypad) in mini2440.?

- Jagan.

Datasheet maybe

GPJ or GPF 0..7