Ronald Leenes wrote:

Hi,

for a project we have a very large key-matrix (32x24). We have a problem
with phantom keys (when three keys in a rectangle are pressed, also the
fourth corner is seen as pressed).
How do we solve this problem? I know something can be done with diodes,
but we can't get it to work. Can somebody give some hints.

An additional problem is that the 'keyboard' consists of panels that can
only be opened with great difficulty.

What is the most clever way to interface say 500 switches to a computer
(serial or usb)?

Don't. use fewer keys and context switch, or use a virtual keyboard, it
would be cheaper than the hardware.

Al