I am trying to display sensor data on my Android phone (target 4.3) received from a transmitting arduino type device. The transmission takes place via Bluetooth. I am able to connect to the arduino type device and even share data, however for some reason I am having synchronization issues.
The way the arduino is setup right now, after a successful connection it waits for a byte to be received from my phone (unsigned byte value 255), when it receives this byte it responds by sending a packet (3 bytes) containing information from three different sensors i.e.
packet:
byte 1: temperature data
byte 2: cadence data
byte 3: speed data
All I have to do is display this data(which is updating live) repeatedly until the user terminates the connection on the android phone.
Here is my code I feel I am making a minor error somewhere in my logic.
MessageHandler
Handler mHandler = new Handler(){
public void handleMessage(Message msg){
super.handleMessage(msg);
switch(msg.what){
case SUCCESS_CONNECT:
// Do Something;
ConnectedThread connectedThread = new ConnectedThread((BluetoothSocket)msg.obj);
Toast.makeText(getActivity(),"CONNECTED",Toast.LENGTH_SHORT).show();
/*
* Could send test string here
*/
/*
* String connect_string = "test";
* connectedThread.write(connect_string.getBytes());
*/
connectedThread.start();
break;
case MESSAGE_READ:
byte[] readBuf = (byte[])msg.obj;
int tempInt = byteToInt(readBuf[0]);
int cadenceInt = byteToInt(readBuf[1]);
int speedInt = byteToInt(readBuf[2]);
EditText temperatureData = (EditText)getActivity().findViewById(R.id.temperatureData);
temperatureData.setText(Integer.toString(tempInt));
EditText cadenceData = (EditText)getActivity().findViewById(R.id.cadence);
cadenceData.setText(Integer.toString(cadenceInt));
EditText speedData = (EditText)getActivity().findViewById(R.id.speed_data);
speedData.setText(Integer.toString(speedInt));
}
}
};
ConnectThread
public class ConnectThread extends Thread {
private final BluetoothSocket mmSocket;
private final BluetoothDevice mmDevice;
public ConnectThread(BluetoothDevice device) {
/*
* Use a temporary object that is later assigned to mmSocket,
* because mmSocket is final
*/
BluetoothSocket tmp = null;
mmDevice = device;
// Get a BluetoothSocket to connect with the given BluetoothDevice
try {
// MY_UUID is the app's UUID string, also used by the server code
tmp = device.createRfcommSocketToServiceRecord(MY_UUID);
} catch (IOException e) { }
mmSocket = tmp;
}
public void run() {
// Cancel discovery because it will slow down the connection
mBluetoothAdapter.cancelDiscovery();
try {
// Connect the device through the socket. This will block
// until it succeeds or throws an exception
mmSocket.connect();
} catch (IOException connectException) {
// Unable to connect; close the socket and get out
try {
mmSocket.close();
} catch (IOException closeException) {
Toast.makeText(getActivity(), "Connecting to device failed!", Toast.LENGTH_LONG).show();
}
return;
}
// Do work to manage the connection (in a separate thread)
mHandler.obtainMessage(SUCCESS_CONNECT, mmSocket).sendToTarget();
}
/** Will cancel an in-progress connection, and close the socket */
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) { }
}
}
ConnectedThread
private class ConnectedThread extends Thread {
private final BluetoothSocket mmSocket;
private final InputStream mmInStream;
private final OutputStream mmOutStream;
public ConnectedThread(BluetoothSocket socket) {
mmSocket = socket;
InputStream tmpIn = null;
OutputStream tmpOut = null;
// Get the input and output streams, using temp objects because
// member streams are final
try {
tmpIn = socket.getInputStream();
tmpOut = socket.getOutputStream();
} catch (IOException e) { }
mmInStream = tmpIn;
mmOutStream = tmpOut;
}
public void run() {
byte[] buffer; // buffer store for the stream
int bytes; // bytes returned from read()
// Keep listening to the InputStream until an exception occurs
while (true) {
try {
// Read from the InputStream
buffer = new byte[3];
byte maxByte = (byte) 1;
mmOutStream.write(255);
bytes = mmInStream.read(buffer,0,buffer.length);
// Send the obtained bytes to the message handler
mHandler.obtainMessage(MESSAGE_READ,buffer).sendToTarget();
}
catch (IOException e) {
break;
}
}
}
/* Call this from the main activity to send data to the remote device */
public void write(byte[] bytes) {
try {
mmOutStream.write(bytes);
} catch (IOException e) { }
}
}
Byte To Int Method
public static int byteToInt(byte b){
int value;
value = b & 0xFF;
return value;
}
The data I receive is being displayed but often ends up wrong mostly because the byte array sequence is off which causes the wrong values to be displayed. I have been trying to figure this out for a while and any input would be helpful.
