How to mount diodes on a keyboard hack ?

[VaRioR]

Hi all !

I've a question about mounting diodes on a keyboard hack...

I've found an old microswitch keyboard and I decided to hack it in order to construct a desktop controller.
I have to connect diodes on each buttons of the controller to avoid the "ghosting" and "masking" effects.

I've 2 questions about that :
- what's the good method to found the mounting direction of the diodes ?
- what pin of the pushbuttons i have to solder on ?

Thx for your answers...
VaRioR

[Tiger-Heli]

Hi all !

I've a question about mounting diodes on a keyboard hack...

I've found an old microswitch keyboard and I decided to hack it in order to construct a desktop controller.
I have to connect diodes on each buttons of the controller to avoid the "ghosting" and "masking" effects.

I've 2 questions about that :
- what's the good method to found the mounting direction of the diodes ?
- what pin of the pushbuttons i have to solder on ?

Thx for your answers...
VaRioR

First off, it's been my experience that a modern keyboard will be unaffected by diodes, b/c blocking in the firmware keeps the keypresses from registering anyway.  A really old keyboard might not have the problems.

For the Pushbuttons, you connect The NC and the COM terminal between the Row and Column Inputs of the keyboard matrix.  Doesn't matter what order.

For the diodes, polarity would depend on how the microcontroller scans the matrix but it might not matter.

You only need one diode per switch.

Both http://www.dribin.org/dave/keyboard/one_html/ and the ButtonBox (MatrixCard) circuit schematic shows the diode wired to allow current to flow from the column to the row inputs, but I don't know that you can go by this.

Let me know if you find any thing further.