Devlog #1 - Not sus USB stick

Sooo I started on my rubber ducky usb. Heres what I want it to do:

• On connect, it should act as two USB devices, a mass storage device using the SD card, and a keyboard.
• It should be able to send HID keyboard commands over the esp32 s3 wroom 1’s Wifi or bluetooth through a UI.

After procrastinating for a while I started on the schematic.

At first I really wanted to add a USB A pcb edge connector, but I decided that was a bad idea because the PCB needed to be 2cm thick, and it would wear out really easily, so I decided to go with USB C.

The SD card part is kindda confusing

While connecting the SD card receptacle, I learned that the s3 wroom 1 uses a gpio matrix, and the majority of the pins can be used as SPI pins! That’s really convenient for my situation because I get flexibility with the routing.

Attached is the schematic and semi sorted pcb (pls give me some feedback 😭😭😭) =)

I finally figured out how the case goes together. It’s a three-part stack: the top frame, the mounting plate, and the bottom case. The switches snap into the plate first, and then their pins fit into the PCB underneath. The tolerances and dimensions for everything was a bit confusing at first.

I wrapped up the CAD files and moved to the firmware. I went with QMK since I already know my way around it. Defining the matrix, mapping the rows and columns to the RP2040, and setting up a basic default keymap was pretty straightforward.

The last step was writing the README and prepping the GitHub repo for submission. The documentation took ages because I wanted a clear image of all 3 parts of my case. I spent a while trying to figure out how to generate a spaced out diagram of the case layers until I realized I just needed to use the “explode” function in my CAD software to pull the parts along an axis.

Anyways, attached are my finished PCB, schematic and CAD!

My PCB was looking a really boring and plain so I added some orpheus graphics on the silkscreen on the front and back of the PCB.

The case is almost done, I finally figured out how to position the plate sketch.

While designing the case, I realized that the top of the XIAO RP2040 (the usb c receptacle) doesn’t fit, so I’ll have to flip it around to the other side of the PCB.

So I started designing my cool macropad today.

Design

I decided to go with a 3x3 layout with a rotary encoder on top (I chose it because it looks cool). I put that into Keyboard Layout Editor for the PCB.

PCB

It’s a 3x3 matrix wired up to a Seeed Studio XIAO RP2040 and an EC11 switch rotary encoder.

Case

I started the case in Fusion, this is where I hit the wall (pun intended). I can’t figure out how to do the plate for the sandwich mount, the outlines where really off and nothing was aligning properly. I guess that’s a future me problem.

I’m gonna (hopefully) figure out how the plate thingies work, add a USB C cutout for my microcontroller and I’ll be finished (again, hopefully finished).

Attached is where my case is at right now and my finished PCB + schematic. Here’s the github repo for anyone who wants to check it out =)
https://github.com/poggersv2/macropad

I followed a tutorial on how to start making my own OS. All it does right now is print hello world…