skio connects Flutter apps to USB serial devices, UART ports and USB cameras,
on Android, macOS, Windows, Linux and in the browser.
It calls native APIs directly with jnigen, dart:ffi and
dart:js_interop, so there are no platform channels, and the logic lives in
testable Dart.
$ flutter pub add skio_usb_serialIllustration of the calls in the code sample below.
Packages
Each package covers one transport. They share permissions, errors, serial settings and device matching through skio_core.
Send and receive data with USB serial devices: Arduino and ESP32 boards, USB-to-serial adapters, instruments. Android over USB OTG, macOS apps, and Chrome or Edge with Web Serial. Windows and Linux are in progress.
Open serial ports by path: the UART, RS-232 and RS-485 ports built into Android panels, Jetson and Raspberry Pi boards, Windows COM ports and USB adapters on Linux and macOS. Pure Dart FFI, nothing native to build, and it also runs in Dart command-line tools.
USB cameras (endoscopes, microscopes, webcams) on Android and the web: live preview, JPEG photos, the camera's snapshot button, and your choice of resolution. macOS, Windows and Linux are in progress.
The shared building blocks: one permission API, one error family, device filters, serial settings and opt-in logging for every skio package.
How it works
skio calls the platform APIs through generated bindings and dart:ffi. Buffering, framing and timeouts run in Dart, where you can test them. The diagram shows USB serial; skio_uart goes through dart:ffi to libc on Android, Linux and macOS and to kernel32 on Windows, and skio_uvc_camera takes the same path to UVCAndroid on Android and getUserMedia in the browser.
LineReader, one HardwareException type.
jnigen → UsbManager
Direct JNI calls, USB OTG.
dart:ffi → IOKit + termios
No native code to compile.
js_interop → Web Serial
Chrome and Edge.
What it looks like
Open a USB adapter or a UART and exchange bytes, or open a camera and take a photo. Errors come from one sealed type, so a switch can handle every case.
DeviceFilter to match ports by vendor and product IDSerialConfig for baud rate, data bits, parity, stop bits and flow controldtr / rts set in the config, so ESP32 and Arduino boards don't reset on openLineReader for lines and UTF-8 split across readsUvcSize to choose the camera resolution from what it supportsSkioLog opt-in logs, down to every byte, for bug reportsfinal ports = await UsbSerialPort.list();
final port = await UsbSerialPort.open(ports.first,
config: const SerialConfig(baudRate: 115200));
port.input.listen((bytes) => print(bytes));
await port.write(utf8.encode('hello\n'));
await port.close();// '/dev/ttyS3' on a panel, 'COM3' on Windows, '/dev/ttyTHS1' on a Jetson
final port = await SerialPort.open('/dev/ttyS3',
config: const SerialConfig(baudRate: 9600));
port.input.transform(const LineReader()).listen(print);
await port.write(utf8.encode('READ\r\n'));
await port.close();final cameras = await UvcCamera.devices();
await UvcCamera.access.requestAccess(cameras.first);
final cam = await UvcCamera.open(cameras.first,
preferred: const [UvcSize(1920, 1080), UvcSize(1280, 720)]);
// in build(): UvcPreview(camera: cam)
final photo = await cam.capture(quality: 90);
cam.buttonPresses.listen((_) => cam.capture());try {
// ... call any skio plugin
} on HardwareException catch (e) {
final advice = switch (e) {
AccessDenied() => 'Please allow access.',
Disconnected() || DeviceNotFound() => 'Reconnect the device.',
DeviceBusy() => 'Close other apps using it.',
_ => e.message,
};
}Platform support
All four packages are on pub.dev. The stable ones have been tested with real hardware on Android, macOS and the web; skio_uart is new and in beta.
| Package | Android | macOS | Windows | Linux | Web |
|---|---|---|---|---|---|
| skio_usb_serialUSB serial adapters and boards | stableUSB OTG, Android 7.0+ | stableAny /dev/cu.* port |
in progressUse skio_uart today | in progressUse skio_uart today | stableWeb Serial, Chrome and Edge |
| skio_uartSerial ports by path | betaBuilt-in UARTs, /dev/ttyS* |
beta/dev/cu.* |
betaAny COM port | betaJetson, Raspberry Pi, PCs | n/aNo serial ports in browsers |
| skio_uvc_cameraUSB (UVC) cameras | stableUSB OTG, Android 7.0+ | in progress | in progress | in progress | stablegetUserMedia; no snapshot button |
| skio_coreShared types | pure Dart | pure Dart | pure Dart | pure Dart | pure Dart |
skio_uart.skio_uart.Get started
Each package's README on pub.dev explains every feature with examples.
One command each. skio_core comes with them. skio_uart also works with dart pub add.
$ flutter pub add skio_usb_serial
$ flutter pub add skio_uart
$ flutter pub add skio_uvc_cameraA USB serial terminal, a UART terminal and a USB camera viewer. Each package has one in example/.
$ git clone https://github.com/skio-flutter/skio
$ cd skio/packages/skio_usb_serial/example
$ flutter runBrowsers only list serial ports the user has picked. Call request() from a button tap.
FilledButton(
onPressed: () => UsbSerialPort.request(),
child: const Text('Choose port'),
)Sandboxed apps need it in both DebugProfile.entitlements and Release.entitlements.
<key>com.apple.security.device.serial</key>
<true/>dialoutYour user needs access to serial ports for skio_uart. Log out and in again afterwards.
$ sudo usermod -aG dialout $USERSwap the platform for a fake in your tests. Your own logic runs as plain Dart.
import 'package:skio_usb_serial/platform_interface.dart';
UsbSerialPlatform.instance = MyFakePlatform();Principles
A few rules every package follows.
skio is open source and free to use. Stars, bug reports and pull requests all help it grow.