FlSerial

A high-performance, asynchronous serial port plugin for Flutter, using Dart FFI and Native Assets on desktop/mobile and the Web Serial API on browsers.

Platform	Transport	Notes
Windows	FFI → native C++ / Win32	COM1, COM3, …
Linux	FFI → native C++ / termios	/dev/ttyUSB0, /dev/ttyACM0, …
macOS	FFI → native C++ / termios	/dev/cu.usbserial-…
Android	USB Host API (platform channel)	USB-serial adapters: CH340, FTDI, CP210x, CDC ACM, PL2303
Web	Web Serial API (dart:js_interop)	Chrome / Edge 89+

Features

Asynchronous I/O — native C++ worker thread keeps the Flutter UI thread free
Reactive streams — incoming data and events (connect / disconnect / line status) via Stream<SerialEvent>
Modem line tracking — real-time CTS, DSR, RI, DCD status (desktop/macOS/Linux)
Flow control — hardware RTS/CTS and software XON/XOFF
Android USB Host — no root required; permission dialog handled automatically
Web Serial — browser port picker dialog on first connect; works in Chrome and Edge
Native Assets — compiled via hook/build.dart, no manual .so/.dll copy needed

Installation

dependencies:
  flserial: ^0.7.0

Quick start

import 'dart:typed_data';
import 'package:flserial/flserial.dart';

final serial = FlSerial();

// Listen before opening so no events are missed
serial.events.listen((event) {
  switch (event.type) {
    case SerialEventType.connected:
      print('Port opened');
    case SerialEventType.data:
      print('Received: ${String.fromCharCodes(event.data as Uint8List)}');
    case SerialEventType.disconnected:
      print('Port closed');
    default:
      break;
  }
});

// Scan available ports
final ports = await FlSerial.availablePorts();
print(ports); // e.g. [COM3, /dev/ttyUSB0, Web Serial Port]

// Open a port
final config = SerialConfig(baudRate: 115200);
final ok = await serial.open(ports.first.path, config);

if (ok) {
  serial.write(Uint8List.fromList('PING\n'.codeUnits));
}

// Close when done
await serial.close();
await serial.dispose();

SerialConfig

Parameter	Type	Default	Description
`baudRate`	int	115200	Baud rate
`dataBits`	int	8	Data bits (5–8)
`stopBits`	int	1	Stop bits (1 or 2)
`parity`	int	0	0 = none, 1 = odd, 2 = even
`flowControl`	int	0	0 = none, 1 = RTS/CTS, 2 = XON/XOFF

Platform notes

Android

Add to your app's AndroidManifest.xml:

<uses-feature android:name="android.hardware.usb.host" />

The plugin requests USB permission at the OS level when you call open(). The connection opens automatically once the user grants it.

Supported USB-serial chips: CDC ACM, FTDI FT232, Silicon Labs CP210x, CH340/CH341, Prolific PL2303 (HX and HXN).

Web

Scanning always returns a single "Web Serial Port" entry. Calling open() on it triggers the browser's native port-picker dialog — no permission is needed beforehand. The dialog requires a user gesture (button tap), which the open() call from a button handler satisfies.

Browser support: Chrome 89+, Edge 89+. Not supported in Firefox or Safari.