Troubleshooting

Troubleshooting

USB

"No USB serial device found"

• Use a data-capable USB-C cable (not charge-only) or a proper USB-A OTG adapter.
• Confirm the Flipper shows as VID 0x0483 / PID 0x5740.
• Re-plug and accept the Android USB-permission dialog. The app auto-reconnects every ~2 s.

Connected but no data

• Make sure the Flipper is in the running state (you pressed OK on a frequency), not sitting on the editor screen.

Bluetooth

Work through these in order — they're the real causes we've seen, most common first.

1. The Flipper is "invisible" / no device in the scan

• Is Bluetooth ON on the Flipper? The status line must show BT:adv, not BT:off.
• Is the official Flipper app open? Close it. Only one BLE central can hold the link; its background service will grab the Flipper and make it disappear here.
• Custom-named Flipper? It won't carry the "Flipper" prefix — it still appears in the device picker by its own name; pick it there.

2. It finds the Flipper but won't connect / drops instantly

• Stale pairing from a previous session or the official app. Fix it cleanly:
  1. Android Settings → Bluetooth → forget "Flipper".
  2. Flipper Settings → Bluetooth → Forget All Paired Devices.
  3. Reconnect from the app and accept pairing on both screens.
• Tapping the Flipper in Android's system Bluetooth settings does nothing — that's normal. Always use the app's Connect Flipper button.

3. Connected (BT:ok) but the readout stays "— MHz / — dBm"

This means the link is up but the phone isn't receiving the data stream. It's already handled in current builds, but for reference the causes were:

• The app must bind the TX characteristic (indications), not the flow-control notify characteristic.
• Android can serve a stale cached GATT table after re-pairs/re-flashes — the app forces a cache refresh before discovery.
• On Android 13+ the value arrives via the newer onCharacteristicChanged(…, byte[]) callback; the old one returns null.

If you ever see this on a modified build, update to the latest APK.

Solver / accuracy

RMS error is huge (> 100 m)

• Your captures are probably collinear — spread out to 90°+ around the source.
• Wrong environment: set the path-loss n to match your surroundings.
• Multipath (urban/indoor): treat the result as a rough search area, not a fix.

Estimate points the wrong way

• Classic multipath — a reflection arrived stronger than the direct path. Re-capture from different angles; enable outlier rejection (drawer).

GPS is inaccurate

• Indoor GPS is poor. Capture outdoors with a clear sky view; the app needs a good fix per capture.

Still stuck?

Open an issue with the Bug report template — include Flipper firmware version, Android version, transport (USB/BLE), and a capture export (.json/.csv) if it's solver-related.