Android 串口通信

Android 串口通讯可以通过使用 USB 转串口线连接串口设备，并通过 Android 应用程序与其进行通信。以下是在 Android 应用程序中使用串口通讯的步骤：

1. 获取 USB 权限：在 AndroidManifest.xml 文件中添加以下权限：

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

在应用程序中获取 USB 权限：

private static final String ACTION_USB_PERMISSION = "com.android.example.USB_PERMISSION";
private PendingIntent mPermissionIntent;
private UsbManager mUsbManager;
private UsbDevice mDevice;

mUsbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
mPermissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0);

IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);
registerReceiver(mUsbReceiver, filter);

HashMap<String, UsbDevice> deviceList = mUsbManager.getDeviceList();
Iterator<UsbDevice> deviceIterator = deviceList.values().iterator();
while (deviceIterator.hasNext()) {
    UsbDevice device = deviceIterator.next();
    if (device.getVendorId() == VENDOR_ID && device.getProductId() == PRODUCT_ID) {
        mDevice = device;
        mUsbManager.requestPermission(mDevice, mPermissionIntent);
        break;
    }
}

private final BroadcastReceiver mUsbReceiver = new BroadcastReceiver() {
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        if (ACTION_USB_PERMISSION.equals(action)) {
            synchronized (this) {
                UsbDevice device = (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);

                if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)) {
                    if(device != null){
                        // 权限已获取，进行串口通讯
                    }
                }
                else {
                    Log.d(TAG, "permission denied for device " + device);
                }
            }
        }
    }
};

2. 打开串口：使用 UsbManager 打开串口连接：

private UsbDeviceConnection mConnection;
private UsbSerialPort mPort;
private UsbSerialDriver mDriver;

List<UsbSerialDriver> availableDrivers = UsbSerialProber.getDefaultProber().findAllDrivers(mUsbManager);
if (!availableDrivers.isEmpty()) {
    mDriver = availableDrivers.get(0);
    mConnection = mUsbManager.openDevice(mDriver.getDevice());
    if (mConnection != null) {
        List<UsbSerialPort> ports = mDriver.getPorts();
        mPort = ports.get(0);
        mPort.open(mConnection);
        mPort.setParameters(9600, 8, UsbSerialPort.STOPBITS_1, UsbSerialPort.PARITY_NONE);
    }
}

3. 读写数据：使用 UsbSerialPort 进行数据读写：

private UsbSerialPort mPort;
private byte[] mReadBuffer = new byte[4096];

private UsbSerialPort.ReadCallback mCallback = new UsbSerialPort.ReadCallback() {
    @Override
    public void onReceivedData(byte[] data) {
        // 处理收到的数据
    }
};

public void writeData(byte[] data) {
    try {
        if (mPort != null) {
            mPort.write(data, WRITE_TIMEOUT);
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

public void readData() {
    try {
        if (mPort != null) {
            int len = mPort.read(mReadBuffer, READ_TIMEOUT);
            if (len > 0) {
                byte[] data = Arrays.copyOf(mReadBuffer, len);
                // 处理收到的数据
            }
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

以上就是在 Android 应用程序中使用串口通讯的基本步骤。需要注意的是，不同的串口设备可能需要不同的参数进行设置，具体的参数需要根据设备的要求进行设置。