HackPad – Handmade Arduino MIDI Controller

HackPad is a handmade, fully customizable MIDI controller based on Arduino Pro Micro. Its 16 pressure-sensitive, RGB backlit pads work with any DAW, synthesizer or drum machine over USB or TRS MIDI — and every single parameter is configurable directly from the device, without touching a computer.

HackPad uses a 0.96″ OLED display and a Navigation Rotary Encoder with push button to navigate its two operating modes. Configurations are stored in an external EEPROM AT24C256 (up to 201 banks) and retained without power. It connects via Micro USB (MIDI IN & OUT) and features 1× TRS 3.5mm MIDI OUT + 1× TRS 3.5mm MIDI IN for analog connectivity.

Key Features

16 pressure-sensitive pads — velocity sensitive, RGB backlit, 4×4 grid
Navigation Rotary Encoder with push button for menu navigation
0.96″ OLED display — real-time settings and parameter monitoring
Two operating modes — Keyboard Mode and Custom Mode
Chord Finder — 50 scales, pads light up to show correct notes
MIDI output lighting — pads respond to incoming MIDI from your DAW
Plug & play — USB bus-powered via Micro USB
1× TRS 3.5mm MIDI OUT + 1× TRS 3.5mm MIDI IN — analog MIDI for hardware synths and drum machines
External EEPROM AT24C256 — up to 201 banks stored directly on device
Copy & Swap — duplicate or exchange pad configurations
Magnetic connectors — chain multiple Hack Midi Mask devices side by side
Open source hardware — Arduino Pro Micro based, GPL v3 license

Two modes

Keyboard Mode

In Keyboard Mode, HackPad works as a chromatic pad controller. Select your root note and scale from the OLED menu, and the 16 pads are automatically mapped to the correct notes — lit up in real time. Perfect for playing melodies, chords or beats without ever hitting a wrong note.

Custom Mode

In Custom Mode, every pad is fully independent. Assign any MIDI channel, note, CC value, minimum and maximum velocity to each pad individually. Use Copy to duplicate a pad’s settings, or Swap to exchange two pad configurations. Save everything into a named bank in the EEPROM and recall it instantly.

Chord Finder

One of HackPad’s most distinctive features. Select any of 50 available scales from the menu — major, minor, pentatonic, blues, modes, and more — and the pads light up to show which notes belong to that scale.

Chord Finder in action

MIDI output lighting

HackPad listens to incoming MIDI messages and lights up the corresponding pad in real time.

MIDI output lighting in action

Magnetic connectors

Place two or more Hack Midi Mask controllers side by side and they connect automatically via magnetic connectors, sharing power and MIDI communication.

In action

HackPad and TE OP-XY in action

📖 Full documentation, source code & build files on GitHub
📸 Follow the project on Instagram: @hackmidimask
🛒 Buy HackPad →

Explore the full family

HackFad — 4 slide faders + 5 pots
HackPot — 17 rotary potentiometers
HackRot — rotary encoders
UNO — 16 pads + 2 pots + joystick, plug & play
DUE — 16 pads + 6 pots, plug & play
The Story — how it all started

Prototyping

HackPad didn’t arrive fully formed. Before the first PCB, before the OLED menu, before the Chord Finder — there was a handwired prototype, a breadboard, and a lot of trial and error. These are the photos from that process: the early builds, the component tests, the moments where things started to click into place.