New to keyboard design, seeking start point...

[alexblues145]

Hi, have been looking at keyboard design for a few weeks and staggering upon different bits of information, not clicking together as yet.   Maybe unusual but i'm looking to build a two button keyboard (F4 and F12 keys) to work with some hardware I have.   Also, from the different keyboards I have tried, only HP keyboards seem to work....  Does anyone have any good starting points?

[metalliqaz]

Also, from the different keyboards I have tried, only HP keyboards seem to work....

I have no idea what this means.

Anyway if you want to build something custom from scratch, the easiest route is the direct-wired matrix of Cherry MX keys.  A bunch of people do that (see the Making Stuff Together subsection).

[alexblues145]

Thanks for the reply, i will look at  Cherry MX keys, and also the making stuff subsection.  I was abit unsure what subsection would be relevant to post in.

As for the HP keyboards only working,  the computer runs on the FreeRTOS operating system, and only seems to work with hewlett packard brand keyboards.

thanks for your help again.

[Findecanor]

Welcome!

If you are going to make just a two-button keyboard with no special features, then I think that the easiest and cheapest thing would be to scavenge the controller from an existing keyboard and connect your key switches to that.
On most cheap "rubber dome" keyboards, the controller is on a small circuit board with the actual switches in a set of plastic membranes. There are those where the controller is on the membrane itself, but they are not as common.

The keys switches of a typical keyboard are logically laid out in the intersections of a "matrix". There are two sets of lines from the controller to the keys: the matrix "rows" and the matrix "columns". This means that each switch is on one line in the rows and one line in the columns. In a rubber dome/membrane keyboard, the top membrane is the columns and the bottom membrane is the rows (or vice versa).
Trace which lines on the matrix correspond to F4 and F12 respectively, and connect the corresponding lines on the controller to your switches. Nothing else should need to be connected. It is possible that the two switches could share the same row or column.