我正在尝试通过蓝牙发送数据，但是Serial.available（）总是返回0

Question

I have created an android app that (theoretically) sends data to the arduino via bluetooth. I know that I have managed to get connectivity(the led on the bluetooth module stopped blinking) but the Serial.available() isn't changing when I write some values. I have tried using different apps (from the play store) - no luck.

The arduino code which suppose to read the data:

void setup() {
Serial.begin(9600);
Serial.println("Simple Motor Shield sketch");
}
void loop() {
if(Serial.available()>0){
Serial.println("in");
for(int i=0;i<=2;i++){
  joystick[i] = Serial.read();
}
for(int i=0;i<=2;i++){
  Serial.println(joystick[i]);
}
delay(1);
} 
}

joystick[] is an int array

android code:

    bluetoothIn = new Handler() {
        public void handleMessage(android.os.Message msg) {
            if (msg.what == handlerState) {                                     //if message is what we want
                String readMessage = (String) msg.obj;                                                                // msg.arg1 = bytes from connect thread
                recDataString.append(readMessage);                                      //keep appending to string until ~
                int endOfLineIndex = recDataString.indexOf("~");                    // determine the end-of-line
                if (endOfLineIndex > 0) {                                           // make sure there data before ~
                    String dataInPrint = recDataString.substring(0, endOfLineIndex);    // extract string
                    int dataLength = dataInPrint.length();                          //get length of data received

                    recDataString.delete(0, recDataString.length());                    //clear all string data
                }
            }
        }
    };

    btAdapter = BluetoothAdapter.getDefaultAdapter();       // get Bluetooth adapter
    checkBTState();

    // Set up onClick listeners for buttons to send 1 or 0 to turn on/off LED
    btnLeft.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            mConnectedThread.write("0");    // Send "0" via Bluetooth
            Toast.makeText(getBaseContext(), "Turn off LED", Toast.LENGTH_SHORT).show();
        }
    });

    btnRight.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            mConnectedThread.write("1");    // Send "1" via Bluetooth
            Toast.makeText(getBaseContext(), "Turn on LED", Toast.LENGTH_SHORT).show();
        }
    });
    layout_joystick.setOnTouchListener(new View.OnTouchListener() {
        public boolean onTouch(View arg0, MotionEvent arg1) {
            js.drawStick(arg1);
            if (arg1.getAction() == MotionEvent.ACTION_DOWN
                    || arg1.getAction() == MotionEvent.ACTION_MOVE) {
                //int x = js.getX();
                //int y = js.getY();
                int angle = (int)js.getAngle();
                int distance = (int)js.getDistance();
                int maxDist = js.getOffset()+js.getLayoutHeight();

                distance =(int)(distance/(maxDist/9));
                angle=(int)(angle/40);
                distance=Math.max(distance,-9);
                distance=Math.min(distance,9);
                angle=Math.max(angle,-9);
                angle=Math.min(angle,9);
                //mConnectedThread.write(String.valueOf(x));
                //mConnectedThread.write(String.valueOf(y));
                mConnectedThread.write(String.valueOf(angle));
                mConnectedThread.write(String.valueOf(distance));
                Log.i("Bluetooth","Distance: " + distance);
                Log.i("Bluetooth","Angle: " + angle);

            }

            return true;
        }
    });
}

private BluetoothSocket createBluetoothSocket(BluetoothDevice device) throws IOException {

    return  device.createRfcommSocketToServiceRecord(BTMODULEUUID);
    //creates secure outgoing connecetion with BT device using UUID
}

@Override
public void onResume() {
    super.onResume();

    //Get MAC address from DeviceListActivity via intent
    Intent intent = getIntent();

    //Get the MAC address from the DeviceListActivty via EXTRA
    address = intent.getStringExtra(DeviceListActivity.EXTRA_DEVICE_ADDRESS);

    //create device and set the MAC address
    BluetoothDevice device = btAdapter.getRemoteDevice(address);

    try {
        btSocket = createBluetoothSocket(device);
    } catch (IOException e) {
        Toast.makeText(getBaseContext(), "Socket creation failed", Toast.LENGTH_LONG).show();
    }
    // Establish the Bluetooth socket connection.
    try
    {
        btSocket.connect();
    } catch (IOException e) {
        try
        {
            btSocket.close();
        } catch (IOException e2)
        {
            //insert code to deal with this
        }
    }
    mConnectedThread = new ConnectedThread(btSocket);
    mConnectedThread.start();

    //I send a character when resuming.beginning transmission to check device is connected
    //If it is not an exception will be thrown in the write method and finish() will be called
    mConnectedThread.write("0");
}

@Override
public void onPause()
{
    super.onPause();
    try
    {
        //Don't leave Bluetooth sockets open when leaving activity
        btSocket.close();
    } catch (IOException e2) {
        //insert code to deal with this
    }
}

//Checks that the Android device Bluetooth is available and prompts to be turned on if off
private void checkBTState() {

    if(btAdapter==null) {
        Toast.makeText(getBaseContext(), "Device does not support bluetooth", Toast.LENGTH_LONG).show();
    } else {
        if (btAdapter.isEnabled()) {
        } else {
            Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            startActivityForResult(enableBtIntent, 1);
        }
    }
}

//create new class for connect thread
private class ConnectedThread extends Thread {
    private final InputStream mmInStream;
    private final OutputStream mmOutStream;

    //creation of the connect thread
    public ConnectedThread(BluetoothSocket socket) {
        InputStream tmpIn = null;
        OutputStream tmpOut = null;

        try {
            //Create I/O streams for connection
            tmpIn = socket.getInputStream();
            tmpOut = socket.getOutputStream();
        } catch (IOException e) { }

        mmInStream = tmpIn;
        mmOutStream = tmpOut;
    }

    public void run() {
        byte[] buffer = new byte[256];
        int bytes;

        // Keep looping to listen for received messages
        while (true) {
            try {
                bytes = mmInStream.read(buffer);            //read bytes from input buffer
                String readMessage = new String(buffer, 0, bytes);
                // Send the obtained bytes to the UI Activity via handler
                bluetoothIn.obtainMessage(handlerState, bytes, -1, readMessage).sendToTarget();
            } catch (IOException e) {
                break;
            }
        }
    }
    //write method
    public void write(String input) {
        byte[] msgBuffer = input.getBytes();           //converts entered String into bytes
        try {
            mmOutStream.write(msgBuffer);                //write bytes over BT connection via outstream
        } catch (IOException e) {
            //if you cannot write, close the application
            Toast.makeText(getBaseContext(), "Connection Failure", Toast.LENGTH_LONG).show();
            finish();

        }
    }
}

Answer 1

Sorry for the unclarity, basically what I wanted to do is to check if I had any data available on the bluetooth serial connection. So I hoped that Serial.available() would be more than 0 when I sent data.Yet, the Serial.available() and Serial.Read() didn't seemed to work when I sent data. * I have managed to solve the problem using the program from: http://www.circuitmagic.com/arduino/arduino-and-bluetooth-hc-06-to-control-the-led-with-android-device/ *

Answer 2

I think you have connected Bluetooth module on serial RX,TX pins of arduino board. this is not the case. You need to use separate serial for communication with Bluetooth. You can use software serial for this purpose otherwise Bluetooth module won't work. The reason behind this is that the arduino uses same serial pins to communicate with PC (Serial terminal and program load) so it cannot simultaneously send data to Bluetooth.

Have a look at here: https://bellcode.wordpress.com/2012/01/02/android-and-arduino-bluetooth-communication/