Universal Keypad System

[aratti]

I have been working quite intensely on the possibilty to remove the columns cross-interference defect on the diodes decoding keypad (previous project), but I have to admit without too much success.

So I have decided to abandon the diodes decoding project and use a pic device with more IO pins. I decided to use a 16F873 (just because I had some available) and with the extra IO pins and more memory available, I came up with this new keypad that I named : Universal Keypad System.

The features :

Max 40 keys obtained with a matrix 10 Columns x 4 Rows

Via software, columns are sizable to any number between 1 to 10

Works with Interrupt on change technique, using DT instant interrupts routine (Thank you Darrel)

Works on 3 selectable levels using one key press, giving a max
of 117 characters available for a 40 keys keypad.

Formula to obtain number of characters available for different column size: Chars=(Columns x Rows x 3) - 3

Every single key can be modified by the user, using the keypad tool application.

By default “select” key is always the rightmost key of row # 4


Two way serial TTL communication @ 9600,n,8,1


Wake up positive trigger (25 ms) on a dedicated pin is generated before sending any character

Auto repeat function can be enabled - disabled via software


Keypad configuration Downloadable and uploadable


Special windows application tool for keypad setup, available


Download big zip file (320Kb) with manual, schematic and software @ http://techni.caliti.es/blog/

[T.Jackson]

Certain it is impossible to eliminate the "column defect", as you put it, without additional parts. Additional parts which would defeat the overall appeal of the design: low-cost.

Nice veroboard protos you have there. Almost as neat as I used to be able to do them.

Peace,

Trent Jackson

[aratti]

Nice veroboard protos you have there. Almost as neat as I used to be able to do them

Thank you Trent, no doubt is a good trait, that we have in common, and it pays back when hardware debugging is required.

Al.

[T.Jackson]

If you're silly enough to submit them, www.siliconchip.com.au will probably publish some of your projects.

They will pay you approx $100 a page. But be aware that they will probably initiate a false conspiracy against you, in an attempt to sell more magazines.

Trent Jackson