Smolpad

SmolPad

SmolPad is an open-source, custom 3x3 mechanical macropad powered by the Seeed Studio XIAO RP2040 microcontroller. It features a 3x3 diode key matrix, an EC11 rotary encoder for volume control, and a 0.91" I2C OLED display for a plain text output (for now) , all housed in a custom 3D-printed case running KMK Firmware .

Features

3x3 Key Matrix: Direct-soldered MX mechanical switches with 1N4148 diodes . EC11 Rotary Encoder: Smooth volume adjustment and press-to-mute functionality. 0.91" I2C OLED Display: 128x32 resolution driven by the SSD1306 display controller displaying status information. Compact Case Design: Custom 2-piece case secured with M3 heat-set brass inserts. Easy Customization: Powered by KMK / CircuitPython—edit shortcuts on the fly by modifying main.py like a USB drive file.

Keymap Row 0 i) Media play/pause ii) Brightness Increase iii) Brighness Decrease Row 1 i) Super/Windows key ( i know this one is weird but the one on my keyboard doesnt work so i will use this for the timebeing). ii) Audio Mute iii) Copy ( Ctrl + C) Row 2 i) Cut (ctrl + x) ii) Paste (ctrl + v) iii) undo (ctrl + z)

Rotary Encoder i) Clockwise Turn - Volume Up ii) Counter-Clockwise - Volume Down iii) Push Switch Press - Mute Toggle ( will be later used to switch layers)

OLED Display i) currently Displays only a single static text i.e. Smolpad active

All the Above can and will be most likely changed later on .

Project Structure

HackPad CAD Top.step Top.stl Bottom.step Bottom.stl Hack Club Knurled Knob.step PCB smolpad.kicad_pcb smolpad.kicad_pro smolpad.kicad_sch smolpad.step gerbers(final).zip firmwarefiles boot.py kb.py main.py lib kmk Imagaes Case Bottom.png Combined.png Top.png PCB 3d model.png Schematic.pdf BOM.csv README.md

NOTE :- PLEASE CHECK THE BOM.csv FOR THE MATERIALS

Assembly instructions

PCB Fabrication: Upload production/gerbers/gerbers.zip to a PCB manufacturer (such as JLCPCB) with standard 1.6mm thickness and default settings.

3D Printing: Print the enclosure parts (smolpad_case_top.step and smolpad_case_bottom.step) .

Component Soldering: Solder the 1N4148 diodes onto the back of the pcb , ensuring correct polarity . Solder the mechanical MX-style switches and the EC11 encoder Solder the Seeed Studio XIAO RP2040 microcontroller and the 0.91-inch OLED display Enclosure Assembly: Mount the assembled PCB into the 3D-printed case using M3 screws.

Firmware Flashing & Setup

The SmolPad runs on CircuitPython with KMK firmware using the Seeed Studio XIAO RP2040. Enter Bootloader Mode: Connect the XIAO RP2040 to your computer via USB and double-tap the reset button. A drive named RPI-RP2 will appear.

Install CircuitPython Runtime: Drag and drop the official CircuitPython UF2 bootloader runtime onto the RPI-RP2 drive. The board will reboot and mount a new drive named CIRCUITPY.

Upload Firmware Files: Copy your firmware script files (main.py, kb.py, and the kmk/ library folder) directly into the root directory of the CIRCUITPY drive.

Test: The board will automatically execute main.py and initialize your keymap, rotary encoder, and OLED display.

Acknowledgements :- i) Usage of Ai for understanding features of Kicad/Onshape , Usage of ai for guidance in few areas like firmware , Usage of ai for identifying errors and resolving them ii) All resources are not owned by me (except case and Pcb however you are free to use them if you want to).
iii) Created with the guidance of https://hackpad.hackclub.com/guide , https://youtu.be/8WXpGTIbxlQ?si=IzrQN_IX_nW7LFwR . iv) Built with support from the Hack Club grants and resoureces —massive thanks to them for funding the hardware and making this project a reality. v) Built for Stardance hackclub CONTACT INFO :- mandeepswami2010@gmail.com

Suggestions / Issues / Complaint(s) are accepted and appreciated for the betterment of the macropad.