Hackpad

Mediapad

Mediapad is an 9 key hackpad with a rotary encoder, an OLED Display. It also has 20/16 SK6812 MINI-E LEDs, and uses QMK firmware.

Features:

• 128x32 OLED Display
• EC11 Rotary encode
• 20 SK6812 MINI-E LEDs. We gotta make somethin' for party nah??
• cool designed case

Video

Watch it here if the player above does not load.

CAD Model:

Everything fits together using 6 M3 Bolts and heatset inserts. 4 for the case and 2 for the PCB.

It has 8 separate printed pieces. 3 are parts of the case, 1 is a spacer for the glow and 1 is for the OLED display as a support.

<img src=CAD/assets/image.png alt="Schematic" width="500"/>

PCB

I made my PCB inside KiCad. Libraries I used were originally from the Hackpad website but I also used some that I had found on grabcad

Schematic

<img src=PCB/assets/schematic.png alt="Schematic" width="600"/>

PCB

<img src=PCB/assets/pcb.png alt="PCB" width="500"/>

IRL Results

Firmware Overview

This hackpad uses QMK firmware for everything.

Two builds

The board exists in two LED populations, so the firmware ships as two revisions. They differ only in the LED map keys, encoder and OLED are shared.

The four LEDs rev16 leaves out are last in the WS2812 chain, so the remaining sixteen still light normally. The idle screen prints the count (mediapad 16 LED) so you can tell which build is on the board.

make mediapad/rev20:lixtheyt

The keys

All eight switches are media keys, on every mode except RGB. Only what the encoder does changes from mode to mode.

SW1 play/pause   SW2 rewind       SW3 fast forward   SW6 mute
SW4 prev track   SW5 next track
SW7 repeat       SW8 shuffle      SW9 = the encoder

Rotary encoder

Clicking the encoder opens a mode picker that previews rather than switches:

• Click - opens it, showing the mode you are already in
• Turn - walks the list, nothing has changed yet
• Click again - confirms, and only now does the mode change
• Wait - it lapses and you stay exactly where you were

1. Volume - volume up / down
2. Track skip - next / previous track
3. Arrows - arrow up / down
4. Scroll - mouse wheel up / down
5. Zoom - zoom in / out, sent as Ctrl + wheel so it does not depend on your keyboard layout
6. RGB - the lighting, below

RGB

RGB contains 16 effects. The first six run their own colours (Pinwheel, Vortex, Rainbow wave, Chevron, Splash, Raindrops), the other ten come out in whatever you mix, and several of those react to keypresses and spread outward from the key you hit.

The keys aim the dial, and the dial does the changing:

SW1 red   SW2 green   SW3 blue   SW6 brightness   SW4 effect list

Help browser

Press play/pause + rewind together if you forget what a key does. Turn the encoder to walk the list, click it for the answer, press anything to back out. The list follows whichever mode you opened it from.

The LEDs either side of that key light up with the key itself as the dark gap between them, and the display spells the position out in words. The words are the part that always works the LED grid sits about half a key pitch off the switch grid, so no single LED can point at a key without also looking like it points at its neighbour.

OLED

While something is playing, a scrolling title and artist, a progress bar, and a bottom row carrying play/pause on the left, the clock, and shuffle / repeat symbols on the right. The clock runs locally rather than echoing the host, because Windows only refreshes its playback position every few seconds.

Otherwise: the board name and LED count, the current mode, and either waiting for app (nothing arriving) or nothing playing (the app is connected, but Windows has no media session).

Hidden key combos

Armed on the media modes only on the RGB mode those same switches are colour controls.

You can also reach the bootloader by holding the top left key while plugging in, or by double-tapping the reset button on the XIAO.

Firmware:

I want to note out that the firmware was mostly done by AI due to my limited C knowledge and the difficulty to create a firmware that does such advanced things.

BOM:

• 8x Cherry MX Switches
• 8x Keycaps
• 6x M3x5x4 Heatset inserts
• 6x M3x16mm Screws
• 8x 1N4148 DO-35 Diodes
• 16x/20x SK6812 MINI-E LEDs (16x = encoder has no LEDs)
• 1x 0.91" 128x32 OLED Display
• 1x EC11 Rotary Encoder
• 1x XIAO RP2040
• 1x Case (1x bottom case, 1x middle case, 1x top case)
• 6x Spacers (printed part)
• 1x Display Support (printed part, use a double-sided tape so it will hold)

Companion app (now playing on the OLED)

Companion/mediapad_tray.exe is a portable application made in Python that feeds Mediapad with the latest information about current played media on your computer. Without it the OLED shows the board name and waiting for app, everything except the now-playing screen still works.

As I have mentioned... it is a portable application. That means you don't have to install anything. Just open, mess with it in the tray (where background applications are located) and make sure to enable the setting that allows it to open on start up of your computer, so you don't have to turn it on manually every time you turn on your computer. If you've got no idea where the tray with the background applications is located then please, google it.