From a Raspberry Pi Sidecar to COMPA for iPhone and iPad

COMPA did not begin as an iPhone app.

The first public Compa was a Raspberry Pi touchscreen companion for the SP-404 MKII, the P-6, and other class-compliant gear. It handled the jobs the hardware did not: Link-to-MIDI clock, routing, a screen beside the sampler, and eventually a growing set of session tools.

That project is still on GitHub, with the 0.3.2 release documenting its later Pi chapter. But the current COMPA—the App Store product that launched September 9—lives on iPhone and iPad.

The original idea survived the move

The Pi proved the role. A companion could join the session without pretending to be the center of it. The groovebox remained the thing you played; the screen beside it handled sync, capture, routing, or another useful job.

Moving to iPhone and iPad changed the scale of what was possible. The platform already had a screen, touch, storage, audio and MIDI frameworks, cameras, mature app distribution, and a device many producers already owned. It made more sense as the everyday home for the idea.

The meaning of the name did not change. A compa is still the friend beside the gear.

What the Pi chapter contributed

The original project forced real questions early:

• How does a class-compliant groovebox join a Link session?
• How should MIDI clock and transport move between networked apps and USB hardware?
• What happens when audio and MIDI need different routes?
• How much can a companion automate before it starts getting in the musician’s way?

Those lessons carried forward. So did the open-source work around Link Audio, including PyLinkAudio and Force Link Audio.

Two projects, one history

The Raspberry Pi repository remains the record and source for that hardware project. COMPA for iPhone and iPad is a separate App Store product with its own current manual, releases, and support path.

If you found Rare Data through the Pi project, that work was not erased. It became the research bench for the app that followed.

Explore COMPA for iPhone and iPad · View the original Raspberry Pi project