Bluetooth Classic

Legacy Bluetooth Classic functionality for Zynth applications, providing RFCOMM (SPP) socket communication for serial devices.

[!WARNING] Android Only: Bluetooth Classic is currently only supported on the Android runtime. Calling these methods on iOS will result in an “Unsupported” result or an error.

The @zynthjs/bluetooth/Classic system allows your Zynth application to discover nearby classic devices and establish a raw serial connection using the most commonly used RFCOMM profile (00001101-0000-1000-8000-00805F9B34FB).

Basic usage

Discovery and Connection

Discovery in Bluetooth Classic works differently from BLE; it is a full scan for all nearby discoverable devices.

import { BluetoothClassic } from "@zynthjs/bluetooth";

const setup = async () => {
  // 1. Listen for results
  BluetoothClassic.addListener((event) => {
    if (event.type === "device_found") {
      console.log("Classic device found:", event.device.name, event.device.id);
    }
  });

  // 2. Start discovery
  await BluetoothClassic.startDiscoveryAsync();
  
  // 3. Connect to a specific device via RFCOMM
  const conn = await BluetoothClassic.connectAsync({ 
    deviceId: "00:11:22:33:44:55",
    uuid: "00001101-0000-1000-8000-00805F9B34FB" // Standard SPP UUID
  });

  console.log("Connected to classic device:", conn.connectionId);
};

Reading and Writing Data

Data is transmitted and received as Base64-encoded strings.

const communicate = async (connectionId: string) => {
  // 1. Sending data
  await BluetoothClassic.writeAsync(connectionId, btoa("Hello Device"));

  // 2. Checking for received data (read from queue)
  const incoming = await BluetoothClassic.readAsync(connectionId);
  if (incoming) {
    console.log("Received:", atob(incoming));
  }
};

Special cases

Serial Port Profile (SPP): The default UUID used by Zynth for connections is the industry-standard SPP UUID. Most serial adapters, printers, and medical devices use this profile.
Insecure Sockets: Some older Bluetooth devices do not support secure pairing. You can specify insecure: true in connectAsync to attempt an unauthenticated RFCOMM connection.
HID Limitation: Bluetooth Classic on Zynth does not support direct RFCOMM interaction with HID devices (keyboard, mouse, gamepads) as they are exclusively managed by the OS window manager.

API Reference