MIDI Button Keyboard

This compact MIDI keyboard is designed specifically for musicians who are familiar with the button accordion layout - including chromatic accordion, and other free-reed instruments. While piano-style MIDI controllers are widely available, there has been a lack of accessible and dedicated controllers for button players.

This device fills that gap, offering a portable, versatile, and performer-friendly MIDI interface for composition, live playing, and instrument control.

Layouts

The keyboard supports multiple button-based layouts:

• B-system
• C-system (Continental chromatic accordion layout)
• Diatonic layout (“khromka”)
• Stradella (classic bass/chord layout for the left hand)

With layout switching, the same physical keyboard can be used to simulate either side of a full accordion. For example, the Stradella layout allows you to control external auto-accompaniment modules as if you were playing the bass side of a traditional accordion.

Features

• Five-row button design with ~3.5 octaves of range
• Velocity-sensitive keys - expressive playing through touch intensity
• Supports multiple layouts: B-system, C-system, diatonic (“khromka”), and Stradella
• Transpose function to shift key range by semitones
• Layout mirroring (180°) - useful when mounting the keyboard vertically or adapting to personal preference
• Instrument switching - send program change commands to external synthesizers
• Volume control and echo effect adjustment for connected sound modules
• USB MIDI class compliant - plug-and-play on Windows and Linux
• 5-pin DIN MIDI output via adapter for compatibility with classic synthesizers
• Compact and lightweight - easy to integrate into desktop or stage setups

Hybrid Playability

While this is technically a MIDI controller, its velocity response and layout fidelity make it suitable not only for note entry or control, but also for expressive performance. When mounted vertically, it can serve as a standalone live instrument - especially for musicians who prefer button accordion ergonomics. Compatible with both modern USB setups and classic 5-pin MIDI gear via adapter.

If you’d like to explore alternative layouts or add custom functions - the firmware is flexible and can be extended for experimental use cases as well.