我将Arduino配置为继续在TX端口上写东西,并通过Android Things Developer Preview 3连接到我的Raspberry Pi 3(我确定RX / TX电缆配置正确并且电压正常)。

我正在尝试使用Android Things库的PeripheralManagerService读取数据和写入数据的时间很长。

启动应用程序时出现错误:


  04-11 16:26:13.665 163-163 /? I /外围设备:类型= 1400审核(0.0:44):AVC:拒绝{读写}名称=“ ttyAMA0” dev =“ tmpfs” ino = 1203 scontext = u:r:peripheralman:s0 tcontext = u:object_r:设备:s0 tclass = chr_file许可= 1
  
  04-11 16:26:13.665 163-163 /? I /外围设备:类型= 1400审核(0.0:45):AVC:拒绝{打开} =“ / dev / ttyAMA0” dev =“ tmpfs” ino = 1203 scontext = u:r:peripheralman:s0 tcontext = u: object_r:设备:s0 tclass = chr_file允许= 1
  
  04-11 16:26:13.665 163-163 /? I /外围设备:类型= 1400审核(0.0:46):AVC:拒绝{ioctl}用于路径=“ / dev / ttyAMA0” dev =“ tmpfs” ino = 1203 ioctlcmd = 5401 scontext = u:r:peripheralman:s0 tcontext = u:object_r:device:s0 tclass = chr_file允许= 1


我的代码:

public class MainActivity extends Activity {

private final int BUFFER_SIZE = 64;
private UartDevice rxtx;


public void configureUartFrame(UartDevice uart) throws IOException {
    // Configure the UART port
    uart.setBaudrate(9600);
}

public void writeUartData(UartDevice uart, String msg) throws IOException {
    byte[] buffer = msg.getBytes();
    int count = uart.write(buffer, buffer.length);
    Log.d(TAG, "Wrote " + count + " bytes to peripheral");
}

public void readUartBuffer(UartDevice uart) throws IOException {
    byte[] buffer = new byte[BUFFER_SIZE];
    int count;
    while ((count = uart.read(buffer, buffer.length)) > 0) {
        Log.d(TAG, "Read " + count + " bytes from peripheral");
        Log.d("Message", new String(buffer));
    }
}

@Override
protected void onStart() {
    super.onStart();
        try {
            writeUartData(rxtx, "teste");
            readUartBuffer(rxtx);
        } catch (IOException e) {
            e.printStackTrace();
        }
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    PeripheralManagerService manager = new PeripheralManagerService();

    manager.getUartDeviceList();
    List<String> portList = manager.getUartDeviceList();

    if (portList.isEmpty()) {
        Log.i(TAG, "No UART port available on this device:");
    } else {
        Log.i(TAG, "List of RXTX available ports: - " + portList);
    }

    try{
       rxtx = manager.openUartDevice(portList.get(0));
       configureUartFrame(rxtx);
    }catch (IOException e){
        e.printStackTrace();
    }
}}


有人知道这会是什么吗?

最佳答案

我没有在您的代码中的任何地方注册UartDeviceCallback。您如何轮询UART以获取新的传入数据?没有注册回调,您的应用将需要通过UartDevice.read()定期轮询UART,以获取新的传入字节,我也看不到您的代码。似乎唯一被调用的地方是在onStart()活动回调中。

回调是一种更有效的方法,所以我建议添加它。有关更多详细信息,请查看UART Peripheral I/O Guide

10-06 06:48