usb_serial 0.2.3

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usb_serial #

An Android USB Serial Flutter Plugin

This plugin allows Flutter code to interact with USB serial devices connected to your Android device. For example an FTDI or CDC based USB device.

Getting Started #

Add a dependency to your pubspec.yaml

	usb_serial: ^0.2.3

include the usbserial package at the top of your dart file.

import 'package:usb_serial/usb_serial.dart'

IMPORTANT app\build.gradle #

Edit android\app\build.gradle and add

    compileOptions {
        sourceCompatibility 1.8
        targetCompatibility 1.8

to the 'android' object, see build.grade from the example project for a template on how to do this. Without this you'll get a bunch or Java errors.

Optional #


		<action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />

	<meta-data android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED"
		android:resource="@xml/device_filter" />

to your AndroidManifest.xml

and place device_filter.xml

<?xml version="1.0" encoding="utf-8"?>
    <!-- 0x0403 / 0x6001: FTDI FT232R UART -->
    <usb-device vendor-id="1027" product-id="24577" />
    <!-- 0x0403 / 0x6015: FTDI FT231X -->
    <usb-device vendor-id="1027" product-id="24597" />

    <!-- 0x2341 / Arduino -->
    <usb-device vendor-id="9025" />

    <!-- 0x16C0 / 0x0483: Teensyduino  -->
    <usb-device vendor-id="5824" product-id="1155" />

    <!-- 0x10C4 / 0xEA60: CP210x UART Bridge -->
    <usb-device vendor-id="4292" product-id="60000" />
    <!-- 0x067B / 0x2303: Prolific PL2303 -->
    <usb-device vendor-id="1659" product-id="8963" />
    <!-- 0x1366 / 0x0105: Segger JLink -->
    <usb-device vendor-id="4966" product-id="261" />

in the res/xml directory. This will notify your app when one of the specified devices is plugged in.

Usage of Asynchronous API #

onPressed: () async {
	List<UsbDevice> devices = await UsbSerial.listDevices();

	UsbPort port;
	if (devices.length == 0) {
	port = await devices[0].create();

	bool openResult = await;
	if ( !openResult ) {
		print("Failed to open");
	await port.setDTR(true);
	await port.setRTS(true);

	port.setPortParameters(115200, UsbPort.DATABITS_8,
	  UsbPort.STOPBITS_1, UsbPort.PARITY_NONE);

	// print first result and close port.
	port.inputStream.listen((Uint8List event) {

	await port.write(Uint8List.fromList([0x10, 0x00]));

Usage of transaction API #

This API is a layer on top of the asynchronous part of the library. It provides two Stream Transformers and a Transaction helper based on the StreamQueue class.

  1. Terminated Transformer, this splits incoming data based on a configurable end of message bytes "terminator".
  2. Magic Header + Length byte, this splits incoming data based on a configurable header ( with wildcards! ) and a length byte directly following the header.

In case neither is a fit, you can use one of those Transformers to create you own that is specific to the binary format you are dealing with.

    Transaction<String> transaction = Transaction.stringTerminated(port.inputStream, Uint8List.fromList([13,10]));

    // While using transactions you can still listen to all 
    // incoming messages! (String data) {

    // you can write asynchronous messages as before!
    // BUT you can also write 'transactions'. This is a combination of a flush, write and wait for response
    // with a timeout. If no response is received within the timeout a null value is returned.
    // this sends "AB\r\n"
    var response = await transaction.transaction(p, Uint8List.fromList([65,66,13,10]), Duration(seconds: 1) );
    print("The response was $response");

Dependencies #

This library depends on:

0.2.3 #

  • Fixed threading issue ( PR10 )

0.2.2 #

  • Fixed 3 dart lint warnings.

0.2.1 #

  • Updated the underlying UsbSerial library to 6.0.6
  • Updated the examples

0.2.0 #

  • Added Transformers and Transactions
  • Added unit tests
  • Changed Java naming, if your compile fails delete the 'build' directory and try again.

0.1.1 #

  • Merged pull request 1: Fix for NoSuchMethodException thrown on api level less than 21 during device enumeration.

0.1.0 #

  • Modified the USB Attached/Detach stream from Stream
  • Added ACTION_USB_ATTACHED and ACTION_USB_DETACHED constants to dart interface.

0.0.2 #

  • Fixed crasher when connected or disconnecting a USB device without having a sink attached.

0.0.1 #

  • Initial release, providing easy UART access to Android Flutter apps


UsbSerial full example #

The example/lib/main.dart file contains a full example of how to use the serial library. It is sending data terminated with \r\n and waits for lines terminated with \r\n to arrive. If you don't have a device like that but do have an Arduino at hand the sketch below will create such a magical device for you.

  int i = 0;
  // the setup function runs once when you press reset or power the board
  void setup() {
    // initialize digital pin 13 as an output.
    pinMode(13, OUTPUT);
    while ( !Serial ) {
    digitalWrite(13, HIGH);   // turn the LED on (HIGH is the voltage level)
  // the loop function runs over and over again forever
  void loop() {    
    if ( Serial.available() ) {
      if ( i == 0 ) {
        digitalWrite(13, HIGH);   // turn the LED on (HIGH is the voltage level)
        i = 1;
      } else {
        digitalWrite(13, LOW);    // turn the LED off by making the voltage LOW
        i = 0;
      Serial.write( );

Quick Getting Started #

Below is an abbreviated example showing the essentials to getting the UsbSerial library to work.

import 'package:usb_serial/usb_serial.dart';
import 'package:usb_serial/transaction.dart';

class _MyAppState extends State<MyApp> {
    var _port;    
    StreamSubscription<Uint8List> _subscription;
    void initState() async {
      List<UsbDevice> devices = await UsbSerial.listDevices();
      if ( devices.length == 0 ) {
      _port = devices[0].create();
      if (!await {
      await _port.setDTR(true);
      await _port.setRTS(true);
      await _port.setPortParameters(
        115200, UsbPort.DATABITS_8, UsbPort.STOPBITS_1, UsbPort.PARITY_NONE);
      _subscription = line) {          
    void dispose() {
      if ( _port != null ) {
        _port = null;

    /// elsewhere in your dart file:

    onPressed: () {

Further Examples #

Have a look at the test directory if you need more examples.

Use this package as a library

1. Depend on it

Add this to your package's pubspec.yaml file:

  usb_serial: ^0.2.3

2. Install it

You can install packages from the command line:

with Flutter:

$ flutter pub get

Alternatively, your editor might support flutter pub get. Check the docs for your editor to learn more.

3. Import it

Now in your Dart code, you can use:

import 'package:usb_serial/usb_serial.dart';
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Learn more about scoring.

We analyzed this package on Feb 18, 2020, and provided a score, details, and suggestions below. Analysis was completed with status completed using:

  • Dart: 2.7.1
  • pana: 0.13.5
  • Flutter: 1.12.13+hotfix.7


Package Constraint Resolved Available
Direct dependencies
Dart SDK >=2.0.0-dev.68.0 <3.0.0
async ^2.1.0 2.4.0
flutter 0.0.0
Transitive dependencies
collection 1.14.11 1.14.12
meta 1.1.8
sky_engine 0.0.99
typed_data 1.1.6
vector_math 2.0.8
Dev dependencies
coveralls ^5.2.0