RaceBox
Pair a RaceBox Mini, Mini S or Micro over Web Bluetooth for 25 Hz GNSS in the phone lap timer, with the wire format for the curious.
RaceBox devices stream GNSS position, speed, heading and g-force up to 25 times a second. Outlap’s phone lap timer can pair with one directly from the browser, so your lap times and live delta use dedicated GPS rather than the phone’s.
Pairing
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Use a supported browser.
Web Bluetooth works in Chrome and Edge on Android, Mac, Windows and ChromeOS. It does not work in Safari on iPhone or iPad.
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Switch the RaceBox on and keep it close to your phone.
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Start a timing session in Outlap and choose to connect a RaceBox. Your browser shows a device picker listing devices whose name starts with “RaceBox”. Pick yours.
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Wait for a 3D fix. The timer shows satellites and accuracy. Start driving once the fix is good.
If pairing fails, see Troubleshooting.
What Outlap reads
Each data message carries, per fix:
| Field | Notes |
|---|---|
| Time | UTC, to the nanosecond. Used for lap timing. |
| Latitude, longitude | 1e-7 degrees. |
| Speed, heading | Ground speed (mm/s) and heading (1e-5 degrees). |
| Accuracy | Horizontal accuracy in millimetres, shown in the UI. |
| Satellites and fix type | Fix is 2D or 3D, with a validity flag. |
| g-force X / Y / Z | Milli-g, device frame. |
| Battery | Percentage on Mini / Mini S; the Micro reports input voltage instead. |
Wire format
For developers building on the same device. RaceBox speaks a u-blox-style binary protocol over the Nordic UART service.
| Item | Value |
|---|---|
| BLE service | 6e400001-b5a3-f393-e0a9-e50e24dcca9e (Nordic UART) |
| Notify characteristic | 6e400003-b5a3-f393-e0a9-e50e24dcca9e (device → host) |
| Frame header | 0xB5 0x62 |
| Message | class 0xFF, id 0x01, “RaceBox Data Message”, 80-byte payload |
| Checksum | 8-bit Fletcher over class, id, length and payload, appended as two bytes |
| Byte order | Little-endian |
Frames can arrive split across notifications or several joined together, so a reader must buffer, find the header, read the length, and validate the checksum before parsing. Outlap discards frames that fail the checksum and resyncs on the next header.