Wingie2 MPE

Wingie2 implements the MIDI Polyphonic Expression 1.1 member-channel note, note-ownership, and Pitch Bend path over its existing MIDI 1.0 input, as an optional single Lower Zone with per-note left/right alternating engine assignment. Member Channel Pressure (0xD0) and member CC 74 form one linear 0–254 pressure travel that lengthens decay on the owning side by summing per-note boosts (Poly/Ratio 2s each, up to 6s per side; String/Bar 6s for the single owner); other member CCs are not mapped.

The MPE Switch

MPE is governed by a single switch, exposed as mpe_enabled in the USB configuration page (config schema 6) and stored in flash. Factory default: off. The switch is the only zone authority: MCM (RPN 6 on Channel 1) may resize the zone while the switch is on and is ignored while the switch is off. A restart restores the switched layout.

Switch off — conventional routing

No zone exists. Channels 1–16 are all conventional and follow the configurable Left/Right/Both routing (factory defaults: Left 1, Right 2, Both 3). Notes on channels not assigned to a route do not sound. Channel 13 tuning CC, Channel 14/15 Cave-frequency CC, and Channel 16 global-settings CC are all reachable.

Switch on — standard Lower Zone

One Lower Zone claims every channel: Manager Channel 1, Member Channels 2–16. All notes and Pitch Bend follow the MPE path below; the Left/Right/Both routes do not apply. Member CC other than CC 74 is not mapped, which means the conventional control channels are not reachable while MPE is on: tuning (13), Cave frequency (14/15), and global settings (16) are all taken over by the zone. Use per-note Pitch Bend for tuning, and the USB configuration page for Cave and global settings.

Because the zone covers all 16 channels, notes from dual-zone controllers also sound — both zones' notes are merged into Wingie2's single zone (per-zone separation is lost, nothing is dropped).

Note Assignment and Pitch Bend

• Each Note On in the Zone is assigned to one engine side, alternating left/right in arrival order (the same free-running alternation as the conventional Both route). A side in Cave Mode is skipped: all notes land on the sounding side; if both sides are in Cave Mode, notes are ignored.
• Poly and Ratio Modes each bind a Note On to one of three voices on the assigned side. A free voice is used first; when all three are active, the oldest voice is replaced.
• Member Pitch Bend changes every active voice owned by that Member Channel, on either side.
• Manager Pitch Bend (Channel 1) is global: it changes every active MPE voice on both sides.
• Manager CC (Channel 1) is applied to both sides; Member CC 74 drives the second half of the pressure travel (below), other Member CCs are not mapped.
• String and Bar use the latest Note On as a monophonic owner on the assigned side. Member control stops after its matching Note Off, while the last pitch remains latched and Manager Pitch Bend remains active.
• Note Off is routed by (channel, note) ownership across both sides. A Note On with velocity 0 is treated as Note Off.

Member Pitch Bend defaults to ±48 semitones and Manager Pitch Bend defaults to ±2 semitones. RPN 0 is accepted on Manager and Member Channels; a Member range received on one channel applies to every Member. Pitch Bend state is tracked before Note On so an MPE source can establish a note's initial microtonal offset.

Per-note Expression (0xD0 + CC74)

Osmose-style MPE controllers send an onset burst (Channel Pressure, CC 74, then Pitch Bend) just before Note On; Wingie2 latches both values per channel, so a note sounds with the expression already established.

• Pressure adds decay over the full key travel, summed per side: the Osmose exports its pressure travel as two sequential 7-bit segments — Channel Pressure (0xD0) for 0–127, then member-channel CC 74 rising from 0 once 0xD0 saturates (measured: CC74>0 only while 0xD0 is exactly 127; the Osmose has no per-key Y sensor, so CC74 carries no slide gesture). The two segments form one linear axis E = 0xD0 + CC74 ∈ 0–254, and boost per voice = depth × E/254, with depth 2s per voice in Poly/Ratio (three voices add, capped at 6s per side) and 6s for the single String/Bar owner and conventional channels. Full physical floor is full depth: one key floored is +2s (three floored keys +6s, capped); 0xD0 saturation alone is half travel, +1s per key. Each voice tracks its owner channel's pressure and timbre, including after Note Off, so the tail follows the key as it lifts. Because the Faust graph has one decay slider per side, the three voice boosts are added and written into that slider, clamped to a 20s overall ceiling (the Decay fader itself spans 0.1–10s): with the fader at 10s, pressure can still add its full 6s. CC74 on conventional channels (l/r/both) feeds the same side path; CC74 on the Manager channel has no decay effect, mirroring 0xD0.
• Why not per-voice t60 in the Faust graph: decay_boost_* per-voice sliders watchdog-reset at boot (~10.5s, CPU0 Faust DSP Task starves IDLE). Retried on the current baseline after the revert: -Os still watchdog-resets, -O2 overflows IRAM0 by 80 bytes. The budget is at the edge, so pressure widens the existing per-side decay slider instead; the DSP graph stays unchanged.
• Other Member CCs (besides CC 74) are not mapped to synthesis parameters.
• Conventional (non-MPE) Channel Pressure on a routed channel applies to that side as a whole (single slot, 6s depth like String/Bar).

Tuning

Pitch Bend is applied after the base note has been resolved through Wingie2's current A3 and tuning. An MPE source can therefore provide alternate tuning by sending per-note Pitch Bend before Note On. Select Standard internal tuning when the source should be the only tuning authority. If an internal alternate tuning remains enabled, the internal interval and MPE offset are both applied.

Migrating from the always-on firmware

• The MPE switch is back as mpe_enabled in the USB configuration page (config schema 6), persisted in flash, factory default off.
• With the switch on, the zone covers Channels 2–16 instead of the previous startup layout (Channels 2–7): the earlier silent drop on Channels 11–15 no longer exists.
• With the switch off, Channels 1–7 are conventional again (previously they were always claimed by the zone), so a non-MPE controller on Channel 1 behaves like any other conventional channel.
• The Upper-Zone dual-zone warning is gone: dual-zone controllers now sound on every channel, merged into the single zone.
• Factory default routing for fresh devices is Left 1, Right 2, Both 3. Existing saved settings are not rewritten by the firmware; change the channels in the configuration page if needed.