Bluetooth Sensors: FAQ

Where do sensors work in the app?

Bluetooth LE sensors work exclusively in the mobile app on iOS and Android. The web browser version does not support Bluetooth connections. In the app, go to: Settings → Connections → Sensors or tap the sensor icon in the home header.

Why is my sensor not appearing in "Nearby"?

HR strap not worn / dry: Heart rate strap electrodes must be moistened with water and worn snugly against your chest — a dry or unworn strap transmits nothing.
Bluetooth permissions: Ensure Bluetooth is enabled on your phone and the Freediver app has permission for Bluetooth / Nearby devices (and Location on Android 11).
Active connection elsewhere: Disconnect the sensor from the manufacturer's official app on your phone.
Unnamed devices: The app deliberately hides unnamed Bluetooth devices.
Enable "Show all devices": If your sensor advertises a name but was not automatically recognized as an HR strap or oximeter, toggle this switch at the bottom of the scan sheet.
Already saved: Previously saved devices do not show up in "Nearby" — check the main list on the Sensors screen.

What do the sensor status badges mean?

Waiting: The sensor is saved but currently powered off or out of range. It will automatically connect as soon as you turn it on.
Connecting…: Connection attempt in progress (10-second timeout).
Connected: Sensor is connected and ready to stream live metrics.
Failed: Connection error or pairing rejected (retries 5 times and stops). Tap Connect to retry. On iOS, if pairing fails, choose Forget this device in system Bluetooth settings.
Unsupported: The device does not speak standard Bluetooth profiles or any known vendor protocol.

Why was my sensor removed automatically after connecting?

The app automatically disconnects and forgets a device if, after connecting, it discovers that the device exposes neither heart rate (HR) nor pulse oximetry (SpO₂) services (e.g. only battery level).

Connected, but showing dashes ("–") instead of numbers?

HR strap ("No signal"): No skin contact detected. Moisten electrodes and tighten the strap.
Pulse oximeter: Ensure your finger is inserted properly. If the device is in spot-check mode, switch it to continuous streaming mode (usually by long-pressing the button on the oximeter).
Stale data: If no sample arrives for over 5 seconds, the value fades with a note indicating Last reading N s ago.

Live readings appear on screen, but aren't in the workout summary?

Recording toggle: Tap the sensor card and check Record to workout. Ensure the switch for HR or SpO₂ is turned on (muted series are marked Not recorded).
Start the workout: Data recording begins when you start the workout timer in the app, not when you pair the sensor.

Which sensors are supported?

Standard Bluetooth Profiles (Native Support)

Heart Rate Straps (Heart Rate Service — 0x180D): Any standard BLE HR monitor (e.g. Polar H10, Polar H9, Garmin HRM-Dual, Wahoo TICKR).
Pulse Oximeters (Pulse Oximeter Service — 0x1822): Any standard SIG BLE pulse oximeter supporting continuous or spot-check mode (e.g. Medisana PM 100 connect, ChoiceMMed MD300C228 / MD300CI218 family).
Battery Service (0x180F): Read automatically if exposed by the peripheral.

Supported Models and Protocols

BerryMed: BM1000, BM1000A, and BCI protocol pulse oximeters (name BerryMed).
Masimo: MightySat series.
Yonker: YK series oximeters (e.g. YK-80, YK-81, YK-82, YK-83).
Jumper Medical: E.g. JPD-500F.
Berace: Berace BLE pulse oximeters.
Wellue / Viatom (FS20F): FS20F / VTM 20F models.
Wellue / Viatom (NUS): PC-60E, PC-60F, OxySmart, BabyOximeter, OxyKnight models.
Vibeat: PF-10AW, POD-2B models.
ARSTN: ARSTN BLE pulse oximeters.
LPOW: FSRK-sample-001 model.
Manridy: SP001 model.
Creative Medical: SP-20 model.
Nonin: BLE models 3230, 3240, 3245, 3250.
MEDXING: MEDXING-SpO2 models.
Sejoy: XM-101 model.
c68e-pulse: HR devices using c68e protocol.

Which devices are unsupported?

Bluetooth Classic (non-BLE): E.g. Nonin Onyx II 9560BT.
Batch-download only (no real-time stream): E.g. Viatom SleepU, Viatom O2Ring, Beurer PO60, ChoiceMMed MD300C318T2, BodiMetrics CheckMe, TaiDoc SpO2, 3Plus HR (stored session export only).
Thermometers: E.g. ChoiceMMed CFT308C, Viatom AOJ-20A.

Still having issues?

Contact us via the in-app form in Settings → Help & feedback → Send us a message, or email us at hello@freediver.club with the following details:

The exact Bluetooth advertised name (as shown in "Nearby"),
Device brand and model,
Phone model and OS version (iOS / Android).