Workshop Computer Program Cards

Cosmik C1ZZL3

README

CosmikC1ZZL3

Dual phase-distortion synthesiser, Web MIDI custom-envelope editor, USB MIDI instrument, and probabilistic Turing machine program card for the Music Thing Modular Workshop Computer.

Status: production build promoted from the hardware-tested Web MIDI build
Language: C++ / Pico SDK
Framework: ComputerCard
Creator: Adrian Vos

For a simpler user-facing description of the card, see:

CARD_README.md

Stability Boundary

This production build appears to be at the practical limit of what is stable on this RP2040 card format while keeping the current oscillator, envelopes, Web MIDI custom slots, USB MIDI device/host support, ring/noise, detune, Turing mode, CV outputs, and LED feedback.

The failed experiments are part of the design decision:

  • Keeping the Turing clock running in synth mode caused lockups at maximum settings.
  • Reducing noise depth did not make that clock-persistence branch reliable.
  • Limiting Web MIDI ring/noise settings did not make that branch reliable.
  • Turing MIDI output has not been added because it would increase complexity and processing load for little benefit on this card.

The stable production behaviour is therefore:

  • Turing CV and pulse outputs are generated while in Turing mode.
  • When switching back to synth mode, the last Turing CV and pulse values are held.
  • The Turing clock does not continue running in synth mode.
  • Turing tap tempo has been removed; Y is the only internal clock-speed control.
  • Turing MIDI output is intentionally absent.

Avoid adding background work to the audio callback unless another feature is removed or simplified.

Modes

Switch Middle: PD Synth

  • Main controls pitch.
  • Audio/CV in 1 adds pitch at the hardware-tested 1V/oct scale.
  • X controls phase-distortion amount.
  • Y morphs across the waveform families.
  • CVIn1 adds phase-distortion amount.
  • CVIn2 adds wave control.
  • AudioIn2 is unused.
  • Pulse in 2 triggers the selected envelope and oscillator sync.
  • CV out 1/2 and Pulse out 1/2 hold the last Turing values.

Hold Switch Down: Performance Edit

  • Main controls oscillator 2 detune.
  • X edits ring modulation.
  • Y edits noise/grit modulation.
  • Ring and noise start neutral after reset.
  • If the card starts with the switch down, ring/noise editing is locked until the switch has first left down.
  • Holding switch down from middle for the save gesture keeps the original manual save behaviour for supported performance settings.

Switch Up: Turing Machine

  • Main controls mutation/lock behaviour.
  • X controls sequence length from 2 to 16 steps.
  • Y controls internal clock speed.
  • Pulse in 1 acts as an external clock.
  • CV out 1 carries scaled stepped Turing CV.
  • CV out 2 carries smoothed Turing CV.
  • Pulse out 1 carries the main Turing pulse.
  • Pulse out 2 carries an alternate Turing bit pulse.
  • Audio out 1/2 carry the self-playing stepped oscillator voice.
  • CVIn1 adds clamped phase-distortion amount.
  • CVIn2 adds clamped wave control.

Main, X, and Y use pickup when changing between synth and Turing modes, so stored values do not jump until each physical knob is swept through its held value.

Web MIDI And USB MIDI

The card uses boot-time USB role selection on 2025 Workshop Computer hardware:

  • connected to a computer, it appears as a USB MIDI device for DAW/browser use
  • connected downstream to a class-compliant USB MIDI controller, it can run in USB MIDI host mode

The Web MIDI editor can:

  • edit amplitude and phase-distortion envelopes
  • drag envelope nodes vertically for level and sideways for stage time
  • add and remove up to eight custom presets
  • load a custom envelope into RAM
  • save a custom envelope to card flash
  • delete a saved custom envelope slot from card flash
  • set ring, noise, and MIDI input channel
  • audition envelopes in the browser
  • copy SysEx or C++ envelope data for inspection

Factory presets are never overwritten. The card stores custom envelope shapes; custom names are kept in browser local storage.

Running The Web Editor

Hosted editor:

https://soveda.github.io/CozmikC1zzl3/web-midi/editor/

Use the hosted editor for normal Web MIDI editing. To run the same editor locally from the repository root:

python3 -m http.server 5173 --directory web-midi/editor

Open:

http://localhost:5173

If port 5173 is already in use, choose another port:

python3 -m http.server 5174 --directory web-midi/editor

Use Chrome or another browser with Web MIDI and SysEx support. Press MIDI, then choose the C1ZZL3 output explicitly before pressing Load, Save, Delete, or Set.

Envelope Presets

Factory presets:

  1. Off
  2. Pluck
  3. Double pluck
  4. Bounce
  5. Bell
  6. Brass
  7. Strings
  8. Reverse swell
  9. Evolving digital

Eight custom slots can be loaded from the Web editor and selected after the factory presets during startup envelope selection. LED 6 marks the custom bank, and LEDs 1-3 show the custom slot number.

LED Feedback

In synth mode:

  • LED 1 shows phase-distortion amount.
  • LED 2 shows waveform position.
  • LED 3 shows oscillator 2 level.
  • LED 4 shows ring modulation amount.
  • LED 5 shows noise amount.
  • LED 6 lights while the switch is held down.

In Turing mode:

  • LEDs 1-3 show low bits of the Turing pattern.
  • LED 4 follows Pulse in 1.
  • LED 5 shows sequence length.
  • LED 6 flashes on each Turing clock step.
  • Turning X briefly displays sequence length as binary on the LEDs.

In startup envelope selection:

  • Factory presets use the existing binary LED display.
  • Custom slots light LED 6 and use LEDs 1-3 for the custom slot number.

Hardware Test Coverage

This production build passed:

  • maximum physical controls
  • maximum Web MIDI ring/noise settings
  • factory and custom envelope stress
  • repeated Pulse 2 and MIDI note triggering
  • switch/mode changes
  • USB MIDI device mode from DAW/browser
  • USB MIDI host mode from class-compliant controllers
  • custom envelope save and startup selection

If an overload occurs while testing future changes, reset the card before judging the next test.

Building

cmake -S . -B build
cmake --build build

The promoted production build reported:

FLASH: 62 KB
RAM: 71788 B

Development Notes

The experimental history remains in:

experimental/web-midi/

The failed synth-mode Turing clock persistence builds are archived there and should not be used as future baselines.

⬅️ Back to All Programs ⬆️ Back to Top