DailyDuinoA few days ago, I was recommended a video by Moby Pixel on YouTube where he built a custom MIDI macropad for music composition. It looked like a pretty cool project, and I immediately wanted to build one for myself but not for music, but to automate a couple of on-demand tasks for my day job as a software developer.
I know there are plenty of great, fairly priced macropads available on AliExpress, Tindie, and Lectronz. However, I want to get back into PCB design, as it has been eight years since I last designed a professional board.
I’m also a huge Halo fan. I want my desk setup to feature a Master Chief color scheme, and I want this new macropad to perfectly match my Master Chief controller holder.
While I loved the simplicity of Moby Pixel’s design, I couldn’t find a cheap 4×4 mechanical switch PCB to use for prototyping. That inspired me to build my own.
With this project, I have a few specific goals:
- Design a PCB where mechanical switches can be directly soldered.
- Design a PCB with hot-swap sockets for mechanical switches.
- Design a PCB featuring both hot-swap sockets and RGB LEDs.
- Explore and experiment with QMK and ZMK firmwares.
Through these iterations, I will be packing more components onto a 2-layer PCB, evolving the project from a basic USB HID macropad into a fully featured version with Bluetooth, HID, and LED support. Finally, I will be stepping away from Eagle to use EasyEDA for the design to see how it performs.
The Design
There are a couple of key differences between Moby Pixel's project and mine. First, he uses a dedicated GPIO pin for every switch, whereas I will be using a keypad matrix. Second, his design integrates both the switches and the microcontroller onto a single PCB. In my version, I will design a separate PCB for the microcontroller. This modular approach will allow me to easily swap out microcontrollers to experiment with different firmwares.
Schematic
In the key matrix i added external pull-ups and switch the rows and columns. this is how the schematic looks.
The bill of materials is pretty simple
| Component | Count |
| 1N4148 Diode (SOD-123) | 16 |
| Mechanical Switch of your choice | 16 |
| 10K Resistor (0603) (optional) | 4 |
| 10 Pin 0.1″ Header Pins | 1 |
PCB Layout
The PCB is 82.8mm x 82.8mm and i want to keep the distance between the switchers small so that it will ergonomic and low profile.
Finally, I was happy with my design. It took me a whole of 2 hours to design it and now i have to send it for fabrication. It was pretty easy to order PCBs from easyEDA. I just had to click one button and the PCB design was sent to JLCPCB.com and form there it was very easy and cheap to order the PCBs. I was not sponsored by JLCPCB. *cough *cough please sponsor thanks.
Assembly
I soldered the diodes using a soldering iron and it took me 10 minutes to do that. I soldered on the resistor for pull ups but later removed them because i wanted to use the internal pull ups of the RP2040.
Now for the mounting plate. I designed it using fusion360 and printed it on my 3D printer. The choice of color on this is not so great.
Next, I snapped the mechanical blue switches into place on the mounting plate and it snapped perfectly into place. Nice.
Finally I mounted and soldered the PCB in the top mounting plate with the switches.
Okay, here's where I messed up. I should have also ordered the bottom PCB with a microcontroller but I had to work with what I had on hand for testing the prototype. So, I soldered the Pi Pico i had which has the RP2040 microcontroller.
I connected the macropad to pi pico using the following pin configuration
| Macro Pad Pins | RP2040 GPIO |
|---|---|
| 1 (COL1) | GP9 |
| 2 (COL2) | GP8 |
| 3 (COL3) | GP7 |
| 4 (COL4) | GP6 |
| 5 (ROW1) | GP5 |
| 6 (ROW2) | GP4 |
| 7 (ROW3) | GP3 |
| 8 (ROW4) | GP2 |
| 9 (VCC) | — |
| 10 (VCC) | — |
Now that i have connected everything, I plugged in the Pi Pico to my PC and it showed up as a mass storage device.
Software
I had the sweet temptation of writing the software using AI but i had to resist it hard because there were much more mature projects like QMK (Quantum Mechanical Keyboard ) and ZMK (Zephyr Mechanical Keyboard). For this project i'm using QMK.
I cloned the firmware source from QMK's GitHub repo and then I followed QMK's Setup Guide to setup the development environment. I tried searching for an existing config which would work with my Macropad PCB but i could only find some which were partially compatible. So, I added my own device definition by just adding 2 files and couple of folders. First I created a folder "dailyduino_4x4" in "qmk_firmware/keyboards/handwired" folder then i created a "keyboard.json" file and added the following content and then i saved it.
{ "manufacturer": "DailyDuino", "keyboard_name": "DailyDuino 4x4", "maintainer": "DailyDuino", "bootloader": "rp2040", "processor": "RP2040", "diode_direction": "COL2ROW", "matrix_pins": { "cols": ["GP6", "GP7", "GP8", "GP9"], "rows": ["GP2", "GP3", "GP4", "GP5"] }, "usb": { "vid": "0xFEED", "pid": "0x4C34", "device_version": "1.0.0" }, "features": { "bootmagic": true, "extrakey": true, "mousekey": true, "nkro": true }, "community_layouts": ["ortho_4x4"], "layouts": { "LAYOUT_ortho_4x4": { "layout": [ {"matrix": [0, 0], "x": 0, "y": 0}, {"matrix": [0, 1], "x": 1, "y": 0}, {"matrix": [0, 2], "x": 2, "y": 0}, {"matrix": [0, 3], "x": 3, "y": 0}, {"matrix": [1, 0], "x": 0, "y": 1}, {"matrix": [1, 1], "x": 1, "y": 1}, {"matrix": [1, 2], "x": 2, "y": 1}, {"matrix": [1, 3], "x": 3, "y": 1}, {"matrix": [2, 0], "x": 0, "y": 2}, {"matrix": [2, 1], "x": 1, "y": 2}, {"matrix": [2, 2], "x": 2, "y": 2}, {"matrix": [2, 3], "x": 3, "y": 2}, {"matrix": [3, 0], "x": 0, "y": 3}, {"matrix": [3, 1], "x": 1, "y": 3}, {"matrix": [3, 2], "x": 2, "y": 3}, {"matrix": [3, 3], "x": 3, "y": 3} ] } }
}
After saving the JSON file i created a folder inside the dailyduino_4x4 folder dailyduino_4x4/keymaps/default and the i created a file "keymap.c" inside the default folder and i pasted the following content and saved the file.
// Copyright 2024 QMK
// SPDX-License-Identifier: GPL-2.0-or-later
#include QMK_KEYBOARD_H
enum custom_keycodes { M_STR1 = SAFE_RANGE, M_STR2, M_STR3, M_STR4, M_TERM,
};
bool process_record_user(uint16_t keycode, keyrecord_t *record) { if (record->event.pressed) { switch (keycode) { case M_STR1: SEND_STRING("Hello, World!"); return false; case M_STR2: SEND_STRING("your@email.com"); return false; case M_STR3: SEND_STRING("some other string"); return false; case M_STR4: SEND_STRING("another string"); return false; case M_TERM: SEND_STRING(SS_LGUI(" ") SS_DELAY(300) "terminal" SS_TAP(X_ENT)); return false; } } return true;
}
const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = { [0] = LAYOUT_ortho_4x4( M_STR1, M_STR2, M_STR3, M_STR4, M_TERM, KC_6, KC_7, KC_8, KC_9, KC_0, KC_MINS, KC_EQL, KC_BSPC, KC_TAB, KC_ENT, MO(1) ), [1] = LAYOUT_ortho_4x4( KC_F1, KC_F2, KC_F3, KC_F4, KC_F5, KC_F6, KC_F7, KC_F8, KC_F9, KC_F10, KC_F11, KC_F12, QK_BOOT, _______, _______, _______ )
};
Finally i ran the command "qmk flash -kb handwired/dailyduino_4x4 -km default" and the code compiled and uploaded to the Raspberry Pi Pico which was showing as a mass storage device. Now the Raspberry Pi Pico shows as a USB HID Keyboard.
Success!! It works
The Macro Pad works really well and it is very responsive. Now, for the final touches I have to design the case and print it.
Finishing Touches
I went back to fusion360 to design the case. I really wanted to make it low profile but the wires I soldered need some slack so that i can screw in the Pi Pico and so i made it a bit thick.
I assembled the case with the top PCB and it looks good for a prototype and works great.
Parts and Links
I have few PCBs left and i have put them up on Tindie and Lectronz.
| Part | Quantity | Link |
|---|---|---|
| Blue Mechanical Switches | 16 | Aliexpress |
| Blank Purple XDA Keycaps | 16 | Aliexpress |
| M2 x 4mm Screw | 4 | |
| M2 x 8mm Screw | 4 | |
| Raspberry Pi Pico | 1 | Aliexpress |
| 3D Printed enclosures | 1 | Thingiverse |
| 4×4 Macropad PTH PCB | 1 | Tindie Lectronz |
PTH Switches and Beyond
My next post will be about the socketed PCB with LED backlight and also about the 2 versions of base board i designed with two different microcontrollers RP2040 and nRF52840 and maybe in future i will make a ESP32-S6 Base board. I will also be comparing QMK and ZMK firmware and finally i might be writing my own firmware and configurator. The next version will be following the master chief color scheme and i will be one step closer to my halo themed desk setup.
Thank you very much for reading my ramblings I hope you have gained something useful from my post. Thanks again.
P.S. Please check out my website dailyduino.com thanks.
https://www.dailyduino.com/index.php/2026/05/08/diy-4x4-macro-pad-with-pi-pico-and-qmk-pth-version/
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