Hackyy

Hackyy Pad

A custom 4-key macropad featuring a rotary encoder and an animated OLED display, designed and built from scratch for the Hack Club Stardance challenge.

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Screenshots

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Bill of Materials (BOM)

• 1x Custom PCB (designed in KiCad)
• 1x 3D Printed Enclosure (Top and Bottom halves)
• 1x Seeed Studio XIAO RP2040 Microcontroller
• 4x Mechanical Switches
• 4x Keycaps
• 1x Rotary Encoder + Knob
• 1x 0.91" I2C OLED Display

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Layout & Workflow Shortcuts

I designed this pad as a dedicated desk companion to streamline deep-work sessions, audio control, and quick multitasking:

• Rotary Encoder (Knob):
  • Turn: Smooth master volume adjustment
  • Click: Toggle Play / Pause media
• Switch 1: Quick system audio mute (lifesaver for surprise calls)
• Switch 2: Skip to next track
• Switch 3: Instant virtual desktop toggle (my dedicated "hide distractions / focus" button)
• Switch 4: Custom macro that automatically types out my Gumroad project link
• OLED Display: Runs a custom Bongo Cat animation that rapidly taps its paws along in real-time whenever I press a key or twist the knob!

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The Build Journey & What I Learned

Hardware & Enclosure

• KiCad PCB Design: Routed the board around the Seeed Studio XIAO RP2040. Since it's a compact 4-key layout, I was able to skip the complexity of a traditional diode matrix and wired each switch directly from a GPIO pin to ground.
• 3D Modeling in Onshape: Designed a custom two-part enclosure from scratch. The hardest part was dialing in the exact fit tolerances so the OLED glass, mechanical switch plate, and rotary encoder sat flush without flexing or rattling.

Firmware & QMK

• Directory Structure: QMK was tough to configure at first. I learned the hard way that files can't just live anywhere—they have to follow strict nesting rules (keyboards/hackyy_pad/keymaps/default) for the build pipeline to compile.
• Pin Mapping: Translated physical schematic connections into digital pinouts inside keyboard.json to make sure the RP2040's GPIO lines synced up with the switch matrix.

Pairing with AI as a Tutor

Rather than just copying and pasting blocks of code, I used AI as an interactive pair-programmer to:

• Learn core CAD constraints and modeling concepts in Onshape.
• Decode walls of cryptic red GCC compiler errors (like hunting down a rogue lowercase letter in an enum definition that brought down the whole build).
• Build the frame-swapping logic required to render the Bongo Cat bitmap without lagging key-input responsiveness.

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The 1.5-Hour Tragedy 😭

The most painful bug of this entire project had nothing to do with C code, trace routing, or 3D tolerances—it was time tracking.

I spent over an hour and a half deep in the zone writing firmware and debugging, only to discover that my Hackatime session had been logging to the completely wrong project on the Stardance dashboard. Over 1.5 hours of tracked work vanished into the void. But a end got the time back.

Lesson learned: Always double-check your active project before locking into a build sprint!