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/
