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Hexadecimal Hackpad

I put this custom number pad together because I cannot seem to teach myself not to hit "4" instead of "F" when typing in memory addresses. It is based on a "cospad" PCB from kprepublic.com. Most of the forum posts and similar I found when looking for help with this board were out of date/suffering from link rot, so I'm doing a quick braindump here now that I've gotten everything working.


Assembly Notes:

This board is known as a "cospad". It seems a little old in the tooth at this point (I think I saw the year 2014 somewhere in reference to this board, I am typing this in 2023.) I was unable to get the firmware flashed using the links provided by the vendor. (This included https://xd.tkg.io and https://kai.tkg.io/ as well as misc documents in a Google Drive folder.) I was successful using https://usevia.app to program the keyboard. (This may have required flashing the firmware provided by usevia.app prior to configuration. I used QMK Toolbox to flash. I'm not sure if this step was necessary, I had already done this step before I tried using their online configuration utility.)

usevia.app config: cospad-via.json

In order to boot the board into a flashable mode, you will need to short these two connections: Bottom view: https://i.imgur.com/CNZq6Xd.png mirror Top view: top view

I had previously attempted to use a prebuilt solution: EPOMAKER TH21 21 Keys Hot Swappable Wired Numpad with RGB Backlight, Programmable,Cherry Profile PBT Keycaps for Win/Mac(Epomaker Budgerigar Switch) I was not successful. I do not recommend using this numpad for this project, as the "Fn" key is not reprogrammable using the driver software and is right smack dab where I needed the "F" key to be. It might be possible using other software, I did not explore reflashing the firmware on this unit.

If you just want a hexidecimal numpad without the effort, consider IPv6 Buddy. It's got a couple different keys than what I put together but it works great and the creator seems like a good guy. It is also MUCH CHEAPER than building your own from scratch.

It's mini-USB, which seems appropriately archaic at this point. I only wish it was PS/2.

Glamour Shots:

Original Plan:

Final Product Top View:

Final Product Side View:

Parts List: