Modding an old mehanical laptop keyboard.

[pingmaster]

I have this old 286 with a small alps keyboard I really like and the motherboard is dead(like REALLY DEAD) so no harm done. I have plenty of electronics modding experience so that isnt a big deal. Where should I start(mostly with the controller and case)? There is no controller on the board.

I'll post some pics later but the switches are the white low profile tactile alps and yellow low profile linear alps. The keycaps are thin grey doubleshot. It comes from a Magnavox Metalis 286.

[Blaise170]

I have this old 286 with a small alps keyboard I really like and the motherboard is dead(like REALLY DEAD) so no harm done. I have plenty of electronics modding experience so that isnt a big deal. Where should I start(mostly with the controller and case)? There is no controller on the board.

I'll post some pics later but the switches are the white low profile tactile alps and yellow low profile linear alps. The keycaps are thin grey doubleshot. It comes from a Magnavox Metalis 286.

ATMega32U4 is a good chip to start with since it has a lot of support throughout the keyboard community. As for a case, you could 3D print or weld your own. Alternatively you could get a one-off case built but that would probably cost you hundreds just for the case.

[pingmaster]

I have a 3D printer, no big deal. Does it matter the PCB has no diodes? Will the ATMega32U4 support 2 key rollover properly?

[Blaise170]

Well it supports at least 6KRO properly but depending on the firmware you can also get NKRO working. The Teensy is the most common one I've seen used and it comes with an easy to use flashing software.

[pingmaster]

Well I don't need to worry about 2 key rollover, there are 8 diodes on the board. Do you have some links on where to get started? Also, should I get a flatflex adapter or solder direct with ribbon cable?

https://imgur.com/a/DWgf2

[ErgoMacros]

Hi,

Looks like a 22 pin connector. Digikey, or Mouser may have it.
22 - 6 rows should be no more than 16 columns. You can, and will eventually probably) need to trace the circuits to get it the exact arrangement, and trace the rows/columns back to the connector.

So you need a controller with at most 22 I/O pins free, + a USB port. These are easy to come buy. "Pro Micro" is one popular one.

From there pick any decent software:

    TMK https://github.com/tmk/tmk_keyboard
    QMK https://github.com/qmk/qmk_firmware a superset based upon TMK
    Easy AVR https://github.com/dhowland/EasyAVR)

I don't know if any of the software is better at "ghost key" elimination than the others.

You'll need to tell the software which pins you're using for each row and column. D0,...

Then you need to tell the software which key is at each row/column intersection.

There are many samples of this and it's all well documented.

I guess other options for cases include custom (laser) cut acrylic, usually 4-6 (as I recall) layers, or wood works too.

Good luck! I'm sure you'll find us a group that's generous with our experience.