SouthPad – Southpaw Mechanical Numberpad featuring USB-C

April 2019 – Present

The goal was to design, build, and program a discrete USB number pad from scratch. The primary challenge was that this would be mirrored from a standard keyboard number pad so that it could be used on the left side of a deskspace. This would better allow for the use of a right-handed mouse and a numpad at the same time, which would be useful for a lot of data entry work that I had been doing at work.

The PCB Design of MW-01 Rev 0.1

The design itself was rather straightforward. I could copy most of the work from existing designs and shuffle some things around to accomplish the goal of being mirrored. I added a row of keys above the standard layout to add some increased functionality: Backspace, Equals sign, and the Parenthesis keys. Some minor modification to existing firmware code was needed, but nothing too crazy or difficult.

Proof that the firmware can flash

As of July 2019, the first 4 prototypes have been built, are working, and a few have been sent out for additional testing. Next steps include changes to the layout to allow for it to fit in a proper case (sandwiched or milled), to make some minor aesthetic changes to the silkscreening, and to possibly make some location changes for the non-switch components (diodes, processor, etc) for aesthetic reasons.

The bulk of the details on this project can be found on this project can be found in a Geekhack post linked below.

See Project

In December 2020, I got a message that found this exact post and asked if they could purchase one from me. I’ve been wanting to do some updates as noted above. I also wanted to see if I could change a bunch of the components from SMD to THT. So I set to work, thinking that a simple replacement of all but the ATMEGA would work without issue.

It didn’t.


So after banging my head against the desk over a few rounds of prototypes that didn’t work. I just did some minor updates to the original design. Some fancy masking, cleaning up the traces, a little “professionalization,” and I shipped a round and sent that off.

Comparison to the original numberpad

Then I went to work designing a case that could go with it!

USB-C Fits So Nicely

And finally, I needed to come up with a name for it. MW-01 just doesn’t quite roll off the tongue. So the project was renamed to the SouthPad.

Now it’s listed on my store on Etsy. So you can grab one there!

From here, I’m pretty happy with the project. I’d really like to understand why my THT version doesn’t work, so if anyone reading this has any ideas, feel free to use the Contact form to email me about it, if you’d like to take a look at the files I have.