WebBluetoothProvider

createBluetoothProvider() returns a SerialProvider that uses the Web Bluetooth API over GATT to emulate a serial connection.

Supported service

Implements the Nordic UART Service (NUS) over BLE:

UUID	Role
6e400001-b5a3-f393-e0a9-e50e24dcca9e	Primary service
6e400002-b5a3-f393-e0a9-e50e24dcca9e	TX characteristic (browser writes)
6e400003-b5a3-f393-e0a9-e50e24dcca9e	RX characteristic (browser reads via notifications)

Compatible hardware: nRF52 series, ESP32 BLE UART, HC-08 / AT-09 BLE modules, or any firmware advertising the NUS service.

Import

import { createBluetoothProvider } from "webserial-core";

Factory function

createBluetoothProvider(): SerialProvider

Returns a new SerialProvider instance. No options — the BLE MTU and inter-chunk delay are fixed at safe defaults (20-byte MTU, 10 ms delay).

Usage

import {
  AbstractSerialDevice,
  delimiter,
  createBluetoothProvider,
} from "webserial-core";

AbstractSerialDevice.setProvider(createBluetoothProvider());

class MyBleDevice extends AbstractSerialDevice<string> {
  constructor() {
    super({
      baudRate: 9600, // Ignored over BLE, kept for interface compatibility
      parser: delimiter("\n"),
      autoReconnect: false, // BLE reconnect requires re-pairing; handle manually
    });
  }

  protected async handshake(): Promise<boolean> {
    return true;
  }
}

const device = new MyBleDevice();
await device.connect(); // Opens Web Bluetooth device picker

Per-instance usage

Pass provider directly in the constructor options to scope the BLE provider to a single device instance. The global provider set via AbstractSerialDevice.setProvider() is not touched, so other devices in the same app continue using their own providers.

import {
  AbstractSerialDevice,
  delimiter,
  createBluetoothProvider,
} from "webserial-core";

class MyBleDevice extends AbstractSerialDevice<string> {
  constructor() {
    super({
      baudRate: 9600,
      parser: delimiter("\n"),
      autoReconnect: false,
      provider: createBluetoothProvider(), // BLE only for this instance
    });
  }

  protected async handshake(): Promise<boolean> {
    return true;
  }
}

const device = new MyBleDevice();
await device.connect();

This is especially useful when an app manages multiple device types simultaneously — for example, one BLE device alongside a USB or WebSocket device.

MTU and chunking

BLE has a default MTU of 20 bytes for writeValueWithoutResponse. The provider automatically splits writes into 20-byte chunks with a 10 ms inter- chunk delay to avoid overflowing the BLE stack.

Browser support

Requires Chrome 56+ on desktop (macOS, Windows, Linux with BlueZ), Chrome on Android, or Edge. Not available in Firefox or Safari. Requires HTTPS or localhost.

Notes

• baudRate in SerialDeviceOptions is ignored over BLE. The physical link speed is determined by the BLE connection parameters.
• autoReconnect: false is recommended — BLE reconnection requires the user to re-pair the device through the browser picker.