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Bluetooth troubleshooting
The Bluetooth controller drops mid-set, refuses to pair, or shows up with no triggers. Here's the diagnostic order — OS first, controller second, app third.
Updated
Bluetooth MIDI works 95% of the time and goes sideways the other 5% — and when it does, the failure is almost always in the OS pairing layer, not in Universal Controller MIDI. Diagnose in this order: OS, controller, app.
Pairing won't complete
Hold PS + Create on a DualSense (or PS + Share on a DualShock 4) until the light bar pulses blue. If it pulses white or doesn't pulse at all, the controller already thinks it's paired with something. Forget the device from every host's Bluetooth menu, then retry.
Windows in particular keeps stale pairings. Settings → Bluetooth & devices → Remove, then re-pair. macOS handles this cleanly via System Settings → Bluetooth → ⓘ → Forget.
Controller connects but inputs are missing
The DualSense exposes a different HID profile over BLE than over USB. Some triggers and the touchpad fall back to "limited input" on Bluetooth depending on the OS driver. Symptom: face buttons work, sticks work, but trigger value is stuck at 0 or 127.
Open the Bluetooth tab in the app and click Force re-handshake. That re-issues the report-mode set. If still broken, plug in via USB, confirm everything works, then unplug and the BLE link usually inherits the right report mode.
Symptom → cause matrix
Run down this table before opening a support ticket. Most failures land in one of these buckets.
| Symptom | Most likely cause | Fix |
|---|---|---|
| Light bar pulses white, won't enter pair mode | Already paired elsewhere | Forget device from previous host, hold PS + Create for 5 s |
| Pair completes, no device in MIDI list | Bridge missed the connect event | Quit + relaunch bridge, or click Rescan in Bluetooth tab |
| Triggers stuck at 0 or 127 | BLE report mode not negotiated | Force re-handshake, or USB cycle to inherit |
| Touchpad sends no data over BLE | HID profile downgrade | Same — re-handshake or USB cycle |
| Random 1–2 s dropouts | 2.4 GHz interference | Move dongle off USB-3 port, distance from Wi-Fi router |
| Disconnects after 5–10 min idle | OS power management | Disable "turn off device to save power" on the BT adapter |
| Stuck notes after a dropout | NoteOff never delivered | ⌘ / Ctrl + . for panic, or enable Auto-panic on disconnect |
| Light bar stays orange, never blue | Battery critically low | Charge over USB-C for 10 min before retrying |
Random disconnects mid-set
Three causes, in order of likelihood:
- 2.4 GHz congestion. Your Wi-Fi router, Bluetooth headphones, and the controller are all fighting for the same band. Move the dongle / laptop to within 2 m of the controller.
- USB-3 noise. USB-3 ports leak RF that drowns out 2.4 GHz. Move the BT dongle to a USB-2 port or use a 30 cm extension cable to physically separate them.
- Power management. Windows aggressively sleeps Bluetooth radios. Device Manager → Bluetooth → your adapter → Properties → Power Management → uncheck "Allow the computer to turn off this device".
Latency is fine until it isn't
BLE-MIDI's latency floor is ~7 ms; in practice you'll see 10–25 ms with occasional 60 ms spikes during 2.4 GHz contention. If you need a stable 3 ms floor, that's USB territory. See latency tuning for the wired tuning knobs.
Diagnostic CLI sweep
The bridge ships a one-shot diagnostic command that records 30 seconds of BLE link quality + dropped packets and writes a report you can paste into a support ticket. Drops zero data into your DAW — pure passive monitor.
# macOS / Linux
ucm --diagnose-ble --duration 30 > ble-report.txt
# Windows
ucm.exe --diagnose-ble --duration 30 > ble-report.txt
# Tail of a healthy report:
# RSSI mean -56 dBm, min -68 dBm (good)
# Dropped packets: 0 / 14823
# Connection interval: 7.5 ms (optimal)
# Slave latency: 0 (correct)Real-world scenarios
- Festival stage, lots of phones. 200+ active Bluetooth radios in 50 m. Solution: wire in, full stop. No firmware trick beats radio chaos at that density.
- Co-working space. 30+ Wi-Fi APs, microwave in the kitchen. Disconnects every 3–4 min. Solution: USB cable, or 5 GHz Wi-Fi for the host laptop to free up 2.4 GHz.
- Home studio with mesh router. Disconnects only when fridge compressor cycles. Solution: USB-2 extension on the BT dongle, pulled away from the router.
- Carplay / vehicle. Car BT stack steals priority. Solution: disable car BT on the host phone, or use a different host.
- Old iMac, modern DualSense. Pre-2018 Macs have flaky BLE 4.0 chips. Solution: cheap USB-A Bluetooth 5.0 dongle, disable internal BT in
nvram.