通过蓝牙将来自 Arduino 的超声波传感器的数据发送到 Android

Question

I am working with my diploma thesis and I have problem with communication Arduino -> Android using bluetooth. This is my app: Activity where I want to display distance to obstruction

In the TextView, I want to put data from Arduino with the distance and I need idea, I can't find something, how sending data from different sensors to different Views (for example front, back bumper, left and right).

Here you have arduino code:

 #include <SoftwareSerial.h>
// Mid-back sensor
#define trigPinLeft 11 
#define echoPinLeft 10
// Right-back sensor (looking from back)
#define trigPinRight 7
#define echoPinRight 6
SoftwareSerial btSerial = SoftwareSerial(0,1);

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  btSerial.begin(115200);
  // Mid-back sensor
  pinMode(trigPinLeft, OUTPUT);
  pinMode(echoPinLeft, INPUT);
  // Right-back sensor 
  pinMode(trigPinRight, OUTPUT);
  pinMode(echoPinRight, INPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  long durationLeft, distanceLeft;
  digitalWrite(trigPinLeft, LOW);
  delayMicroseconds(5);
  digitalWrite(trigPinLeft, HIGH);
  delayMicroseconds(5);
  digitalWrite(trigPinLeft, LOW);
  durationLeft = pulseIn(echoPinLeft, HIGH);
  distanceLeft = (durationLeft *0.034 / 2);
  if (distanceLeft>=400 || distanceLeft<=18){
    Serial.println("Out of range"); 
    btSerial.println("Out of range");
  }
  else{
    Serial.print("BACK LEFT: ");
    Serial.print(distanceLeft);
    Serial.println(" cm");
    btSerial.println(distanceLeft + "cm");
  }
  //delayMicroseconds(1);

  long durationRight, distanceRight;
  digitalWrite(trigPinRight, LOW);
  delayMicroseconds(5);
  digitalWrite(trigPinRight, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPinRight, LOW);
  durationRight = pulseIn(echoPinRight, HIGH);
  distanceRight = (durationRight *0.034 / 2);
  if (distanceRight>=400 || distanceRight<=18){
    Serial.println("Out of range"); 
    btSerial.println("Out of range");
  }
  else{
    Serial.print("BACK RIGHT: ");
    Serial.print(distanceRight);
    Serial.println(" cm");
    btSerial.println(distanceRight + "cm");
  }
  delay(10000);
}

This is Android-Studio code where I want one time get data from Arduino to one textView (not working):

public class HomeActivity extends AppCompatActivity {

ImageView imageView;
TextView rearLeft,rearMid,rearRight,frontLeft,frontMid,frontRight;
public static final String PREFS_NAME = "ParkingPrefsFile";
public static final String FIRST_TIME = "firstTime";
public static final String IMAGE_VAL = "imageValue";
private BluetoothServerSocket mmServerSocket;
private BluetoothAdapter mAdapter;
private BluetoothDevice mDevice;
private static final UUID MY_UUID = UUID.fromString("5951c386-e2e7-485d-aebe-a32eec769f7b");

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_home);
    imageView = (ImageView) findViewById(R.id.carView);
    rearLeft = (TextView) findViewById(R.id.rearLeftText);
    rearMid = (TextView) findViewById(R.id.rearMidText);
    rearRight = (TextView) findViewById(R.id.rearRightText);
    frontLeft = (TextView) findViewById(R.id.frontLeftText);
    frontMid = (TextView) findViewById(R.id.frontMidText);
    frontRight = (TextView) findViewById(R.id.frontRightText);
    BluetoothSocket socket = null;
    mAdapter = BluetoothAdapter.getDefaultAdapter();

    SharedPreferences sharedPreferences = getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
    boolean firstTime = sharedPreferences.getBoolean(FIRST_TIME,false);

    if(!firstTime){
        SharedPreferences.Editor editor = sharedPreferences.edit();
        editor.putBoolean(FIRST_TIME,true);
        int image = getIntent().getIntExtra("image", R.drawable.ic_default);
        imageView.setImageResource(image);
        editor.putString(IMAGE_VAL, String.valueOf(getIntent().getIntExtra("image",R.drawable.ic_default)));
        editor.commit();
    }
    else {
        SharedPreferences.Editor editor = sharedPreferences.edit();
        int image = getIntent().getIntExtra("image", Integer.parseInt(sharedPreferences.getString(IMAGE_VAL,null )));
        imageView.setImageResource(image);
        editor.putString(IMAGE_VAL, String.valueOf(getIntent().getIntExtra("image",image)));
        editor.commit();
    }

    /*try{
        //mmServerSocket = mAdapter.listenUsingInsecureRfcommWithServiceRecord("My Adapter", MY_UUID);
        mmServerSocket.accept();
    } catch (IOException e) {
        e.printStackTrace();
    }*/

    /*byte[] buffer = new byte[256];
    int bytes;
    try{
        mmServerSocket.close();
        InputStream inputStream = null;
        OutputStream outputStream = null;
        inputStream = socket.getInputStream();
        outputStream = socket.getOutputStream();

        DataInputStream mmInputStream = new DataInputStream(inputStream);
        DataOutputStream mmOutputStream = new DataOutputStream(outputStream);

        bytes = mmInputStream.read(buffer);
        String readMessage = new String(buffer, 0 , bytes);

        rearLeft.setText(readMessage);
    } catch (IOException e) {
        e.printStackTrace();
    }*/

}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.home_activity_menu,menu);
    return true;
}
}

I compiled and runed app, but after I saw splashscreen, I had white screen and lag on the phone. I hadn't errors in Android-Studio. Thanks for help.

Answer 1

You clearly seem to have threading issue.

In your HomeActivity you have commented out the code that allows to open a Bluetooth Server on your Phone so that your Arduino device may connect to it, supplying the relevant UUID and other relevant parameters in RFCOM mode.

That code, however, is network-related and blocking and therefore should never be executed on the app UI Thread which is responsible to handle all UI tasks such as displaying views, monitoring user interactions (touch events) etc.

This is the reason why your phone displays a white screen with lag.

So you should definitely execute the Bluetooth logic on a separate thread.

I'd propose the following class to handle all bluetooth-related logic. It's very straightforward.

public class BluetoothHandler {

    private final Handler handler;
    private final BluetoothAdapter bluetoothAdapter;

    @Nullable
    private BluetoothServerSocket serverSocket;
    private BluetoothSocket bluetoothSocket;


    public BluetoothHandler(Context context) {
        final HandlerThread ht = new HandlerThread("Bluetooth Handler Thread", Thread.NORM_PRIORITY);
        ht.start(); // starting thread

        this.handler = new Handler(ht.getLooper());

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR2) {
            this.bluetoothAdapter = ((BluetoothManager) context.getSystemService(Context.BLUETOOTH_SERVICE)).getAdapter();
        } else {
            this.bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
        }
    }


    public void startBluetoothServer() {
        // execute code in our background worker thread
        this.handler.post(new Runnable() {
            @Override
            public void run() {
                try {
                    serverSocket = bluetoothAdapter.listenUsingInsecureRfcommWithServiceRecord("name", "your UUID");
                    bluetoothSocket = serverSocket.accept(); // will wait as long as possible (no timeout) so there is blocking

                    // do your logic to retrieve in and out put streams to read / write data from / to your Arduino device

                }  catch (IOException ioe) {

                }
            } 
        });
    }


    @AnyThread
    public void writeData(byte[] data) {
        // remember, all network operation are to be executed in a background thread
        this.handler.post(new Runnable() {
            @Override
            public void run() {
                // write data in output stream     
            }
        });
    }


    @AnyThread
    public void readData(OnDataReadCallback callback) {
        // remember, all network operation are to be executed in a background thread
        this.handler.post(new Runnable() {
            @Override
            public void run() {
                // read data and notify via callback.
            }
        });
    }


    @AnyThread // should be call from your Activity onDestroy() to clear resources and avoid memory leaks.
    public void termainte() {
       try {
           if (serverSocket != null) {
               serverSocket.close();
           }

           if (bluetoothSocket != null) {
                bluetoothSocket.close();
           }
       } catch (IOException ioe) {

       }

        this.handler.getLooper().quit(); // will no longer be usable. Basically, this class instance is now trash.
    }


    public interface OnDataReadCallback {
        @WorkerThread // watch out if you need to update some view, user your Activity#runOnUiThread method !
        void onDataRead(byte[] data);
    }
}