There are a few simple options out there. In the first instance, an Arduino would probably cut it. I could use the serial port, or run a MIDI library to get what I need. Arduino is simple to learn, but I didn’t really need all the extras (or the board size). A Teensy is a smaller, equally affordable, and in some cases, a more versatile microcontroller that gets used a lot in USB MIDI and Music Tech related projects. And there’s a handy MIDI library already out there. So I opted for a Teensy (v3.2).
I sourced a cheap aluminium box here (a nice diecast Hammond box would have been lovely and heavier duty, but they’re expensive. This (Takachi Electric Industrial, MB-14) was 5 quid). For my current purposes, I only need 4 switches, but I got carried away and cut holes for 6 — not realising that this narrows the footprint considerably, making this a tricky thing to trigger with shoes on. It’s also a real mess of wiring inside as a result. If I’d thought about it before, I would have limited the switches to 4. As they say: measure twice, cut once. Lesson learned.
Switches are simple momentary (not-latching) switches, with some LEDs for visual confirmation. Below is a quick breadboard mock-up of the setup:
The code for the Teensy is simple given Josh Nishikawa’s MIDI controller library available here (Note, that I’m interested in MIDI controller numbers/values, not MIDI notes, Teensy can handle regular notes without a library). I’m only using the Pushbutton, assigned as MIDI control numbers (20-25) as they’re typically unassigned. This could also be serial, or MIDI note numbers rather than controller number. The code is simple: when a footswitch is pushed, fire off a MIDI control value of 127, otherwise it’s zero. When the pedal goes down, the LED pin is also lit up. In Max, all I need to read this is a [ctlin], [pak] and a [route 20 21 22 23 24 25] and I’ve got my pedal triggers into Max (see .maxpat in my git below). Easy.
In the Arduino IDE (Teensy uses the Arduino IDE, just with an additional library. There’s a guide to getting started with it here), I wanted the MIDI device to show up with it’s own name, so use the {name.c} file to set that. Set your USB Type to ‘MIDI’ in the Tools menu, and set your Board to ‘Teensy 3.2’, upload all that to the board and you’re done! A cheap, custom MIDI controller…
Improvements:
- We’re gonna need a bigger boat. The initial plan was to include jack sockets and a stereo TRS jack so that I could plug in keyboard sustain pedals and an expression pedal to read as MIDI controllers. The code is simple, but since I didn’t leave myself enough space in the box, they won’t fit now.
- Push-and-hold. My Max patch takes care of held buttons for flexibility, but this could easily be programmed in at the MIDI device level. Currently, if a button is held for x seconds or more, it clears a buffer.
- Writing in at the Teensy level would let me have LED feedback too (light flashes after x seconds). I suppose I could set this anyway, but without it linking directly to the Max value (via serial?) there’s little point.
Files:
- Teensy MIDIfoot code
- Max interface (copy this and select File > ‘New from Clipboard’ in Max)