Summary: When Omniport 1 is wired to a TRS jack on a patchbay (not directly to an expression pedal) and no pedal is plugged in, the firmware reads phantom expression movement — oscillating between ~98% and 100% — even though nothing is connected or moving. This noise appears to interfere with footswitch responsiveness elsewhere on the unit.
Setup:
- Omniport 1 stays permanently wired via TRS cable to a TRS jack on a patchbay.
- An expression pedal is connected to that patchbay jack only when needed — Omniport 1 itself is never unplugged.
Steps to reproduce:
- Leave Omniport 1 connected to the patchbay TRS jack, with no expression pedal plugged into the patchbay.
- Observe expression pedal value in firmware/edit mode.
- Value jitters on/off between 98% and 100% with no physical input.
- While this jitter is occurring, footswitches on the unit intermittently fail to actuate presets when pressed.
Expected behavior: With no expression pedal connected (open/floating TRS ring or tip at the far end), Omniport should either read a stable idle value or be smart enough to reject noise from a floating connection — and should never affect footswitch responsiveness regardless.
Actual behavior: Floating TRS connection is read as noisy analog signal (~2% jitter), and that noise appears to be consuming processing/scan cycles or otherwise interfering with footswitch polling, causing missed actuations.
Workaround / diagnostic finding: Plugging an expression pedal directly into the patchbay jack fixes both symptoms — the reading locks to a stable 100% and footswitches actuate reliably. This isolates the problem to the floating/undriven TRS connection at Omniport 1, not the patchbay or cable itself.
Suggested root cause area: Likely missing input debounce/deadband or pull-up/pull-down termination on the Omniport analog input when unterminated, combined with the expression-read routine apparently sharing cycles with or blocking the footswitch scan loop.
Impact: Any user who wires an Omniport to a patchbay for occasional expression pedal use (rather than a dedicated always-connected pedal) will experience unreliable footswitch performance whenever the pedal isn’t plugged in.
I don’t always bring my expression pedal with me, and I’d rather not reconfigure that omniport (which is hardwired to the patchbay’s expression pedal port) every time I’m with or without the expression pedal - the visual noise doesn’t bother me, it’s the performance impact to every switch that does while the firmware is tracking a phantom expression pedal.