HackRot – Rotary Encoder MIDI Controller

HackRot is a handmade, fully customizable MIDI controller built on Arduino Pro Micro, where every control is a rotary encoder. Unlike potentiometers, encoders have no fixed start or end — they spin freely in both directions, sending relative increment/decrement messages for precise, jump-free control.

HackRot uses a 0.96″ OLED display and a Navigation Rotary Encoder with push button to navigate its settings. 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 includes 1× TRS 3.5mm MIDI OUT + 1× TRS 3.5mm MIDI IN for analog connectivity.

Key Features

All rotary encoders — endless rotation, no dead zones, no value jumps when switching banks
Navigation Rotary Encoder with push button for menu navigation
0.96″ OLED display — real-time monitoring and settings
Plug & play — USB bus-powered via Micro USB (MIDI IN & OUT)
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 encoder configurations
Magnetic connectors — chain multiple Hack Midi Mask devices side by side
Open source hardware — Arduino Pro Micro based, GPL v3 license

Encoders vs Potentiometers

Rotary encoders send relative MIDI messages — turn right to increase, turn left to decrease — rather than an absolute position value. This means no value jumps when switching banks, and infinite resolution limited only by how fast you turn. HackRot is the right tool for any workflow where consistency and precision matter more than visual position feedback.

Full customization

From the OLED screen, select any encoder and configure it: MIDI channel and CC number. Use Copy to duplicate settings to another encoder, or Swap to exchange two configurations. Save everything into a bank in the EEPROM and recall it instantly — no software, no computer.

Magnetic connectors

Like all Hack Midi Mask controllers, HackRot features magnetic side connectors. Place it next to HackPad, HackFad, or HackPot and the devices connect automatically, sharing power and MIDI — building a fully modular, expandable setup without extra cables.