RunBridge LED status guide

RunBridge uses the XIAO nRF52840’s RGB LED to show what it’s doing.

The system decides what to show based on internal state, with a clear priority order.

What you should see during a normal run

A typical sequence looks like this:

  1. Plug in RunBridge → LED cycles briefly, then may go Off or Blue (Scanning)
  2. Pair / connect watch → Magenta (Watch Connected)
  3. Start an Indoor Run → watch subscribes → Blue (Scanning) if treadmill not connected yet
  4. Once treadmill is connected → Solid Green (System Ready)

During the run, Solid Green is the expected state.

Priority order

From highest priority to lowest:

  1. System Ready
    (Watch subscribed + treadmill connected + data flowing)
  2. Treadmill Only
    (Connected to treadmill, waiting for watch)
  3. Watch Connected
    (Connected to watch, not yet subscribed)
  4. Waiting for data
    (Watch subscribed + treadmill connected, but no speed/distance packets yet)
  5. Scanning
    (Watch subscribed, searching for treadmill)
  6. Idle / Sleep
    (No connections)

Whichever condition is true at the highest priority “wins” and sets the LED.

Visual patterns (XIAO nRF52840)

1. System Ready

Watch subscribed + treadmill connected + data flowing

  • LED: Solid green

This is the “happy path” during a run. Data is actually flowing from treadmill → RunBridge → watch. Solid green only appears when the treadmill is sending speed/distance; if the link is up but no packets are received (e.g. belt not started), you’ll see amber instead.

2. Treadmill Only

Connected to treadmill, waiting for watch

  • LED: Double blink red
    • Two short red blinks about every 2 seconds

If you see this pattern:

  • The FTMS treadmill link is up.
  • The watch is not connected yet.

This is not an error — it just means RunBridge is waiting for the watch to connect.

3. Waiting for data

Watch subscribed + treadmill connected, but no speed/distance packets yet

  • LED: Slow blink amber (orange/yellow)

RunBridge is connected to both the watch and the treadmill, but the treadmill is not yet sending FTMS speed/distance data. Common causes:

  • The treadmill only broadcasts data when the belt is moving — try starting the belt.
  • Some treadmills require a workout to be started on the console first.
  • The treadmill may need a moment after connection before it streams.

This state was added so “connected but no data” is clearly visible instead of the LED staying off.

4. Watch Connected

Connected to watch, but not yet subscribed

  • LED: Fast blink magenta
    • On/off roughly every 150 ms

This usually means:

  • The watch found and connected to the sensor.
  • It hasn’t subscribed to run data yet.

Garmin typically subscribes once an activity starts.

If it stays here, try:

  • Starting an Indoor Run activity.
  • Checking the watch sensor settings.

5. Scanning

Watch subscribed, searching for treadmill

  • LED: Slow blink blue
  • About 1 second on / 1 second off

This means:

  • The watch side is ready.
  • RunBridge is scanning for an FTMS treadmill to connect to.

If it never leaves this state:

  • Confirm the treadmill is powered on and broadcasting.
  • Check Compatibility.

6. Idle / Sleep

No connections

  • LED: Off

No active watch or treadmill link. This is normal when:

  • You just powered it on and nothing’s connected yet.
  • You finished a run and everything disconnected.

If you expect it to be doing something but it’s off:

  • Unplug RunBridge, wait a few seconds, and plug back in.