Bluetooth LE in Nodlyn: Scanning, Reading, Subscribing, and Writing GATT Data

Bluetooth Low Energy (BLE) powers modern sensors, wearables, medical devices, smart-home equipment, and industrial IoT hardware. Nodlyn brings BLE directly into your workflows, allowing you to scan for nearby devices, read GATT characteristics, subscribe to live notifications, and even write values to BLE peripherals.

With the Bluetooth LE Connector, you can automate data collection, trigger workflows from sensor updates, or control BLE-enabled devices — all from the comfort of Nodlyn's visual editor.

Step 1: Scan for Nearby BLE Devices

Start by dragging a BLE Scan Devices node onto the canvas. Configure the scan duration (1–60 seconds), and Nodlyn will return a list of advertising BLE devices, including:

• address — the device's Bluetooth MAC address
• name — the advertised local name
• rssiDbm — signal strength
• discoveredAt — timestamp

This is ideal for discovering sensors, wearables, or nearby IoT devices before interacting with them.

Step 2: Read a GATT Characteristic

To retrieve data from a BLE device, use the BLE Read Characteristic node. Provide the device address and the UUIDs of the service and characteristic you want to read.

Nodlyn connects, reads the value once, decodes it using your chosen encoding (UTF‑8, hex, base64, uint8, uint16, float), and disconnects cleanly.

This is perfect for reading sensor values such as:

• temperature
• heart rate
• battery level
• environmental metrics

Step 3: Subscribe to Live Notifications

Some BLE devices push data automatically — for example, heart rate monitors, motion sensors, or telemetry streams. The BLE Subscribe Characteristic node enables notifications and waits for the first incoming value.

Once a notification arrives, Nodlyn returns:

• value — decoded characteristic data
• receivedAt — timestamp
• serviceUuid and characteristicUuid

This allows you to build workflows that react instantly to sensor activity.

Step 4: Write to a BLE Characteristic

To control a BLE device, use the BLE Write Characteristic node. Writing can trigger physical actions — turning on LEDs, activating motors, unlocking devices, or configuring parameters — so this capability is marked as Dangerous and requires explicit arm.

You can choose between:

• Write with Response — reliable, confirmed
• Write without Response — fast, unconfirmed

Values can be encoded as UTF‑8, hex, or base64 depending on the device's protocol.

Example Workflow

Here's a simple automation you can build in minutes:

1. Scan for BLE devices in the room.
2. Select the one with the strongest signal.
3. Read a temperature characteristic.
4. If the temperature exceeds a threshold, send a Telegram alert.

All of this runs locally on your machine — no cloud dependency required.

What's Next?

Try combining BLE with other connectors like HTTP, Slack, Serial Bus, or Tuya. Build dashboards, automate sensor-driven workflows, or control BLE peripherals directly from Nodlyn.

Bluetooth LE opens the door to powerful real-world automation — and Nodlyn makes it accessible to everyone.