connect method

Future<void> connect(String deviceId)

Open connection to deviceId (as returned by listDevices).

Implementation

Future<void> connect(String deviceId) async {
  await disconnect(); // clean up any previous connection

  if (Platform.isAndroid) {
    final device = _androidDevices[deviceId];
    if (device == null) throw StateError('Device not found: $deviceId');
    final port = await device.create();
    if (port == null) throw StateError('Failed to create port for $deviceId');
    final opened = await port.open();
    if (!opened) throw StateError('Permission denied or port busy: $deviceId');
    await port.setPortParameters(
      baudRate,
      UsbPort.DATABITS_8,
      UsbPort.STOPBITS_1,
      UsbPort.PARITY_NONE,
    );
    await port.setDTR(true);
    await port.setRTS(true);
    _usbPort = port;
  } else if (Platform.isWindows) {
    final port = SerialPort(deviceId);
    if (!port.openReadWrite()) {
      throw StateError(
          'Cannot open $deviceId: ${SerialPort.lastError?.message}');
    }
    final cfg = SerialPortConfig()
      ..baudRate = baudRate
      ..bits = 8
      ..stopBits = 1
      ..parity = SerialPortParity.none
      ..xonXoff = 0
      ..rts = SerialPortRts.flowControl
      ..cts = SerialPortCts.ignore
      ..dsr = SerialPortDsr.ignore
      ..dtr = SerialPortDtr.flowControl;
    port.config = cfg;
    _winPort = port;
  } else {
    throw UnsupportedError('USB serial not supported on this platform.');
  }

  // Allow port to stabilise (as specified in the protocol doc).
  await Future<void>.delayed(const Duration(milliseconds: 200));

  // Start the persistent reader for Windows now that the port is stable.
  if (Platform.isWindows) {
    _winReader = SerialPortReader(_winPort!);
    _winReaderSub = _winReader!.stream.listen(
      (data) {
        if (!_winRx.isClosed) _winRx.add(data);
      },
      onError: (Object e) {
        if (!_winRx.isClosed) _winRx.addError(e);
      },
      cancelOnError: false,
    );
  }
}