Spatial Disorientation — card 333

Beta · 0.1.0-alpha14 · Adrian Vos (soveda)

Two independent mono sources become a binaural stereo mix: orbit around the listener, place each source separately, or choose Fig8, Pendulum and Wander movement. Musical inspiration: Neuzeit Instruments Quasar. This is an independent implementation, with no Quasar code, graphics or data.

Use headphones through a suitable monitoring path. This version renders horizontal direction and distance; elevation is a future refinement. 333 is a mnemonic for three spatial axes, not a claim that height is implemented.

Original code/documentation © 2026 Adrian Vos (soveda), MIT. Dependencies and measurement data retain their own terms; see attribution. Keep uf2/NOTICE.txt with redistributed firmware. This follows the notice packaging of Adrian Vos's card 122 and the component-notice standard of card 369; it does not adopt card 369's application freeware license.

Load and start

Flash the tested alpha14 UF2 using the Workshop Computer BOOTSEL procedure. The binary is unchanged from the user-tested development build; checksum. Patch mono Audio 1, optionally a different source to Audio 2. Audio Out 1/2 are the left/right binaural mix. Unplugged inputs are silent. CV outputs are nominal zero and pulse outputs low.

Normal boot always selects Twin Orbits. To select another function, hold Down during reset/startup, choose with Main, then release:

Audio is muted during selection. Mode remains fixed until reset and is not saved.

Twin Orbits

Start Main/X at noon, Y low; turn X slightly right to begin a slow orbit.

X has a centre deadband of approximately ±3% of total travel (6% total width). Clock lock requires two valid edges; intervals 25 ms–60 s. Clocked speed is capped at 2 cycles/sec. Unpatching restores manual speed; timeout is the greater of 3 seconds or three clock intervals. Use pulse widths at least 1 ms. Default clock division is four pulses per turn. CV inputs are nominal, not calibrated.

Spatial Mixer

Up selects A; Down selects B; middle retains the last selection. Main sets that source's position (noon front, ends back), X distance and Y panel level. Both sources retain their placements. CV1/CV2 modulate both positions/distances without changing the saved base; pulse inputs are unused.

Knobs require near/crossing pickup after source selection or placement restoration (about 1.6% tolerance). The selected top/middle LED pair blinks until all three controls are picked up. Defaults: A front, B back, both near at full panel level. Editor A/B trims multiply the individual panel levels. The editor can Read/Apply/ Save both placements, with separate Mixer settings. Separation/clock fields are unused in Mixer.

Disorientation

Choose Fig8, Pendulum or Wander in the editor; Apply auditions and Save retains the choice. Fig8 is the default. Begin with a slow X speed and listen without the display for the first placement comparison.

X controls signed phase speed, centre stops, maximum 1.5 cycles/sec. Up/middle links/opposes the two source phases. Down held freezes phase; release resumes. CV and shape controls can still reshape a frozen position. Pulse1 clocks phase; Pulse2 resets even while frozen. Editor separation offsets source path phase.

Fig8 crosses in front and reaches behind at greater depth/excursion. Pendulum reverses along the same arc at fixed 25% distance. Wander smoothly joins deterministic random positions, with four transitions per phase cycle; reversing X retraces the route. Reset restarts its sequence. Y minimum collapses Fig8/Wander to a front point and Pendulum to its selected centre; it does not mute audio.

Web editor and presets

Open web/index.html in desktop Chrome/Edge. Use a USB-C data cable, close Serial Monitor/other apps, enable MIDI with SysEx permission and select Spatial Disorientation for both ports. iOS is unsupported. If local file MIDI access is blocked, serve the self-contained page from localhost:

python3 -m http.server 8793 --bind 127.0.0.1 --directory web

Visit http://127.0.0.1:8793. The page has no external scripts/services.

• Read: retrieve applied base settings and current Mixer placements.
• Apply: audition staged edits. Ordinary slider edits are not sent automatically.
• Save to card: persist applied settings/placements/default movement; briefly fades audio during the flash write. Apply dirty edits first.
• Reset to init: apply defaults for the active mode; Save separately to retain.
• Export: download displayed settings, including unapplied edits.
• Import: stage a named JSON preset; choose the matching startup mode, then Apply/Save.

Each mode has its own six base settings: phase/angular separation, room, A/B trims, strength and clock division. Mixer adds six placement values; Disorientation adds movement. Defaults: 180° separation, about 29% room, 50% trims, full strength, four clock pulses/cycle, Fig8. Panel controls, CV, phase, motion and live 8mu overrides are excluded from saved configuration.

This editor/firmware uses SysEx and JSON v3, flash v4. Old v1/v2 presets import; old Disorientation presets choose Fig8. Flash v1/v2/v3 migrates in RAM without a boot write, preserving prior banks/placements. Only explicit Save writes flash. Older firmware cannot read v4; export presets before saving if you may downgrade. A corrupt/absent record restores defaults; power-loss recovery is not guaranteed. Protocol details.

Direct 8mu control

Connect 8mu before reset. Rev 1.1 chooses host/device USB role at boot; earlier hardware retains device/editor mode. Change cables and reset when switching roles. Editor and 8mu are used in separate sessions. The inherited identify handshake temporarily loads the 8mu default assignments/bank 1; controller bank selection returns after power-cycling the 8mu. Host adaptation.

Faders require independent near/crossing pickup. In Mixer, source selection rearms faders 1–3 against stored placements. Waiting LEDs blink; picked LEDs show level. Mixer LED8 identifies A steady/B blinking; Mixer ignores motion.

Motion initially off. Orbits motion replaces Main's position; Disorientation motion replaces Main's depth/arc centre. Roll offsets the captured pose; gyro yaw is integrated as a rate. Disorientation Main values clamp at limits. Fader8 scales tilt/rate; zero removes tilt influence and stops rate integration, retaining its held base. A recaptures physical Main/current pose. CV remains additive.

In Disorientation, D release before 500 ms cycles Fig8→Pendulum→Wander; a longer hold shows timing and never cycles on release. LEDs1/2/3 identify the choice for one second. Live choice reverts to the saved movement on disconnect/new session. C and panel Down combine: release both to resume. LED8 steady bright indicates motion, bright blinking indicates Disorientation freeze; timing/selection notices take priority. Turning motion off/disconnecting holds owned Main/X/Y until panel pickup. Mixer handback preserves placements with pickup; Orbits returns to panel. Shared editor trims return to saved values on disconnect. No 8mu gesture saves flash.

LEDs, timing and verification

Top LED pair shows A's left/right direction, middle pair B's. Equal brightness can mean front or back. Bottom left indicates linked motion or Mixer editing A. Bottom right latches for callback ≥18 µs, block ≥1,200 µs or queue fault; hardware reset clears it. Crossing a warning threshold does not stop audio. An actual missed playback block outputs 64 frames of silence (1.33 ms); late audio is discarded. 8mu D diagnostics show 150 µs block-time bands; flashing all LEDs indicates a warning.

The user reports alpha14 tests pass, with peak callback 13 µs and peak block 997 µs, below warning thresholds. Run duration and measurement USB role were not supplied; callback timing excludes surrounding framework ISR work. Build and twelve sanitizer host suites plus editor lifecycle/preset tests pass. Generic short HRTFs may give front/back confusion; headphones and listener differences matter. Hardware protocols and results.

Build: set PICO_SDK_PATH to Pico SDK 2.3.0, then cmake -S . -B build and cmake --build build -j2. ComputerCard 0.4.0 is vendored unmodified; 192 MHz / 1.15 V, 48 kHz, 32 taps, RAM execution, 64-frame block processing with two-block transport latency (2.67 ms). Build provenance.

Attribution and licenses

Original DSP, controls, editor and documentation: Adrian Vos (soveda), MIT. Hardware/build/editor conventions: Chris Johnson's ComputerCard 0.4.0 and web_interface; host integration: Chris Johnson's WaveSeq/EightMU and rppicomidi, MIT notices preserved. Block scheduling adapts Adrian Vos/contributors' Workshop_BlockAudioCard; mathematical sine values reuse You spin me round. Pico SDK is BSD-3-Clause with component notices; TinyUSB is MIT. Newlib/GCC runtime notices and the GCC runtime exception accompany the firmware.

Measured HRTF data: Bill Gardner and Keith Martin, MIT Media Laboratory (1994), HRTF Measurements of a KEMAR Dummy-Head Microphone, Technical Report #280. Original source; retained terms and derivation. The measurements retain their attribution terms and are not relicensed under MIT. Horizontal 32-tap minimum-phase filters use separate analytical ear delays and a synthetic room model. Full source mapping, revisions and notices: THIRD_PARTY_NOTICES.md.