Android怎么实现USB转串口通信
时间: 2024-01-24 10:17:09 浏览: 30
Android 实现 USB 转串口通信的具体步骤如下:
1. 获取 USB 设备的权限:在 AndroidManifest.xml 文件中添加一个 USB 设备的 intent-filter,并在应用程序中注册一个 BroadcastReceiver 来接收 USB 设备的插入和移除事件。
2. 扫描 USB 设备:使用 UsbManager 类扫描 USB 设备并获取其接口和端点信息。
3. 打开 USB 连接:使用 UsbDeviceConnection 类打开 USB 连接。
4. 配置串口参数:使用 UsbDeviceConnection 类设置串口参数,例如波特率、数据位、停止位和校验位等。
5. 发送和接收数据:使用 UsbDeviceConnection 类向 USB 设备发送数据并从 USB 设备接收数据。
下面是一个基本的示例代码,演示如何实现 Android USB 转串口通信:
```java
public class MainActivity extends Activity {
private static final String ACTION_USB_PERMISSION = "com.android.example.USB_PERMISSION";
private UsbManager mUsbManager;
private UsbDevice mDevice;
private UsbDeviceConnection mConnection;
private UsbEndpoint mEndpointIn;
private UsbEndpoint mEndpointOut;
private BroadcastReceiver mUsbReceiver;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mUsbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
// 注册 USB 设备插入和移除的 Broadcast Receiver
mUsbReceiver = new BroadcastReceiver() {
@Override
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) {
// 权限已授予,打开 USB 连接
openUsbDevice(device);
}
} else {
// 权限未授予
Log.d("USB", "permission denied for device " + device);
}
}
} else if (UsbManager.ACTION_USB_DEVICE_ATTACHED.equals(action)) {
// USB 设备已插入,请求权限
UsbDevice device = (UsbDevice) intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
requestUsbPermission(device);
} else if (UsbManager.ACTION_USB_DEVICE_DETACHED.equals(action)) {
// USB 设备已移除,关闭连接
closeUsbDevice();
}
}
};
IntentFilter filter = new IntentFilter();
filter.addAction(ACTION_USB_PERMISSION);
filter.addAction(UsbManager.ACTION_USB_DEVICE_ATTACHED);
filter.addAction(UsbManager.ACTION_USB_DEVICE_DETACHED);
registerReceiver(mUsbReceiver, filter);
// 扫描 USB 设备并请求权限
UsbDevice device = findUsbDevice();
if (device != null) {
requestUsbPermission(device);
}
}
@Override
protected void onDestroy() {
super.onDestroy();
// 关闭连接和释放资源
unregisterReceiver(mUsbReceiver);
closeUsbDevice();
}
private UsbDevice findUsbDevice() {
// 扫描 USB 设备并返回第一个串口设备
for (UsbDevice device : mUsbManager.getDeviceList().values()) {
int interfaceCount = device.getInterfaceCount();
for (int i = 0; i < interfaceCount; i++) {
UsbInterface usbInterface = device.getInterface(i);
if (usbInterface.getInterfaceClass() == UsbConstants.USB_CLASS_COMM) {
return device;
}
}
}
return null;
}
private void requestUsbPermission(UsbDevice device) {
// 请求 USB 设备权限
PendingIntent permissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0);
mUsbManager.requestPermission(device, permissionIntent);
}
private void openUsbDevice(UsbDevice device) {
// 打开 USB 连接并设置端点信息
mDevice = device;
mConnection = mUsbManager.openDevice(device);
if (mConnection != null) {
UsbInterface usbInterface = device.getInterface(0);
for (int i = 0; i < usbInterface.getEndpointCount(); i++) {
UsbEndpoint endpoint = usbInterface.getEndpoint(i);
if (endpoint.getType() == UsbConstants.USB_ENDPOINT_XFER_BULK) {
if (endpoint.getDirection() == UsbConstants.USB_DIR_IN) {
mEndpointIn = endpoint;
} else if (endpoint.getDirection() == UsbConstants.USB_DIR_OUT) {
mEndpointOut = endpoint;
}
}
}
}
}
private void closeUsbDevice() {
// 关闭 USB 连接和释放资源
mDevice = null;
if (mConnection != null) {
mConnection.close();
mConnection = null;
}
mEndpointIn = null;
mEndpointOut = null;
}
private void sendData(byte[] data) {
// 发送数据到 USB 设备
if (mConnection != null && mEndpointOut != null) {
mConnection.bulkTransfer(mEndpointOut, data, data.length, 0);
}
}
private byte[] receiveData() {
// 接收数据从 USB 设备
if (mConnection != null && mEndpointIn != null) {
byte[] buffer = new byte[1024];
int count = mConnection.bulkTransfer(mEndpointIn, buffer, buffer.length, 0);
if (count > 0) {
byte[] data = new byte[count];
System.arraycopy(buffer, 0, data, 0, count);
return data;
}
}
return null;
}
}
```
在上述示例代码中,我们使用 UsbManager 类扫描 USB 设备并获取其接口和端点信息。然后,我们使用 UsbDeviceConnection 类打开 USB 连接,并设置串口参数。最后,我们使用 UsbDeviceConnection 类向 USB 设备发送数据并从 USB 设备接收数据。