Develop Reference

bluetooth InputStream in android gets corrupted after sending with OutputStream

So, I am using my arduino to collect some data and send it to my android app , so that I can store this data in a file, making my android a sort of datalogger.
I am using an hC-06 for this, working at 115200 bauds/sec. Seems to be allright when the arduino sends the data chunks ( 60bytes every chunk) every 100ms aprox.
The problem begins when I "query" the arduino for some special data, by sending a single byte with the OutputStream method. From the moment the app uses the "mmOutStream.write(buffer);" the data received by InputStream becomes unstable, varying the chunk size with random values ( 60 bytes, 45 butes, 100 bytes, etc...)
It seems like using OutputStream kind of corrupts the InputStream buffer...
Anyone has been through this? Thaks in advance
below the code:
// It handles all incoming and outgoing transmissions.
private class ConnectedThread extends Thread {
private final BluetoothSocket mmSocket;
private final InputStream mmInStream;
private final OutputStream mmOutStream;
private boolean send_request=false;
private byte[] send_buffer;
public ConnectedThread(BluetoothSocket socket, String socketType) {
mmSocket = socket;
InputStream tmpIn = null;
OutputStream tmpOut = null;
// Get the BluetoothSocket input and output streams
try {
tmpIn = socket.getInputStream();
tmpOut = socket.getOutputStream();
} catch (IOException e) { }
mmInStream = tmpIn;
mmOutStream = tmpOut;
}
public void run() {
byte[] buffer;
ArrayList<Integer> arr_byte = new ArrayList<Integer>();
// Keep listening to the InputStream while connected
while (true) {
try {
int data = mmInStream.read();
if(data == 0x0A) {
}
else if(data == 0x0D) {
buffer = new byte[arr_byte.size()];
for(int i = 0 ; i < arr_byte.size() ; i++) {
buffer[i] = arr_byte.get(i).byteValue();
}
// Send the obtained bytes to the UI Activity
mHandler.obtainMessage(BluetoothState.MESSAGE_READ
, buffer.length, -1, buffer).sendToTarget();
arr_byte = new ArrayList<Integer>();
}
else {
arr_byte.add(data);
}
} catch (IOException e) {
connectionLost();
// Start the service over to restart listening mode
BluetoothService.this.start(BluetoothService.this.isAndroid);
break;
}
}
}
// Write to the connected OutStream.
// #param buffer The bytes to write
public void write(byte[] buffer) {
try {
mmOutStream.write(buffer);
// mmOutStream.close(); //vdv , close after writing to see if liberates memeory . uncommenting this causes the phone not to connect
//TODO: investigate and solve why a single writing in the outstream causes the inputstream to get corrupted after a while.
// Share the sent message back to the UI Activity
mHandler.obtainMessage(BluetoothState.MESSAGE_WRITE
, -1, -1, buffer).sendToTarget();
} catch (IOException e) {
Log.d(TAG,"write exception"); //vdv
}
}

Bluetooth Chat App answering back same text I sent

Im using one app to send data to the elm327 through bluetooth and I'm trying the AT Z command but everything I get back from the OBD2 is AT Z too, my code is missing something or its supposed to answer like that ? I expected the AT Z to return elm327 text (tested with playstore apps and thats what I got)
// runs during a connection with a remote device
private class ReadWriteThread extends Thread {
private final BluetoothSocket bluetoothSocket;
private final InputStream inputStream;
private final OutputStream outputStream;
public ReadWriteThread(BluetoothSocket socket) {
this.bluetoothSocket = socket;
InputStream tmpIn = null;
OutputStream tmpOut = null;
try {
tmpIn = socket.getInputStream();
tmpOut = socket.getOutputStream();
} catch (IOException e) {
}
inputStream = tmpIn;
outputStream = tmpOut;
}
public void run() {
byte[] buffer = new byte[1024];
int bytes;
// Keep listening to the InputStream
while (true) {
try {
// Read from the InputStream
bytes = inputStream.read(buffer);
// Send the obtained bytes to the UI Activity
handler.obtainMessage(MainActivity.MESSAGE_READ, bytes, -1,
buffer).sendToTarget();
} catch (IOException e) {
connectionLost();
// Start the service over to restart listening mode
ChatController.this.start();
break;
}
}
}
// write to OutputStream
public void write(byte[] buffer) {
try {
outputStream.write(buffer);
handler.obtainMessage(MainActivity.MESSAGE_WRITE, -1, -1,
buffer).sendToTarget();
} catch (IOException e) {
}
}
public void cancel() {
try {
bluetoothSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}

Perhaps you're not reading enough – make sure you concatenate all fragments you read until you receive the actual prompt \r>.
ELM327 usually starts out in echo mode, where it echos every command you are giving to it, that may explain why you're reading it back. Use ATE0 to turn off this behavior.
In general, https://www.sparkfun.com/datasheets/Widgets/ELM327_AT_Commands.pdf explains all that.

Read Bluetooth Message in External android app

I'am a newbie to android Bluetooth and I want to read and store the Bluetooth message in external android app(mine) using internal storage or sqlite. I have tried the android bluetooth-chat sample from GitHub but I don't know how to implement my idea.
Any help would be helpful and thanks

Exchange of bluetooth messages is covered in the android.bluetooth section of the api.
http://developer.android.com/guide/topics/connectivity/bluetooth.html#ManagingAConnection
Here is a basic example of managing a connection and sending/receiving messages:
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 = new byte[1024]; // 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
bytes = mmInStream.read(buffer);
// Send the obtained bytes to the UI activity
mHandler.obtainMessage(MESSAGE_READ, bytes, -1, 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) { }
}
/* Call this from the main activity to shutdown the connection */
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) { }
}
}

Receiving data from raspberry pi in android via bluetooth

I am creating an android app using which I am going to connect to Raspberry pi over Bluetooth.
The issue that I am able to send data to Raspberry pi and it is visible on the terminal (I am using OutputStream in android to send data), but whatever Raspberry pi is sending I am not able to get that in my InputStream.
I have read about using listenrfcomm to get the data sent by another device, but while using createrfcomm also, I have input as well output streams. I am confused as what to use and how to use.
NOTE: Using createrfcomm I am able to send data to Raspberry pi successfully. Only data reception from Rasperry pi is the part that's remaining.
Please advise accordingly.

It would be easier to answer specifically with your code, but I found the API guide example helpful although slightly disjointed at first:
Have a thread to connect:
private 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) { }
return;
}
// Do work to manage the connection (in a separate thread)
manageConnectedSocket(mmSocket);
}
/** Will cancel an in-progress connection, and close the socket */
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) { }
}
}
and a thread to listen and do the work:
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 = new byte[1024]; // 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
bytes = mmInStream.read(buffer);
// Send the obtained bytes to the UI activity
mHandler.obtainMessage(MESSAGE_READ, bytes, -1, 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) { }
}
/* Call this from the main activity to shutdown the connection */
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) { }
}
}
I assume if you can sent that you have BluetoothDevice, and BluetoothAdapter already, and can create and run the connect thread
mConnectThread = new ConnectThread(bluetoothAdapter.getRemoteDevice(deviceAddress));
mConnectThread.start();
In the example bytes is the data read, which is sent to the UI thread with mHandler.obtainMessage. This line can be edited to suit whatever you want to do with the received data.
Example comes from http://developer.android.com/guide/topics/connectivity/bluetooth.html

Bluetooth getInputStream gets multiple/splitted Datapackages?

i'm using the Infamous BluetoothChat-Example from Google to receive a ByteArray.
I know his length (55bytes), his Start Byte (0x69) and his End Byte (0x16) as well as the length of the data in the Array.
I'm quite sure that the Sender sends out 55 Bytes without any interruption but on the BluethootChat Example it looks like i receive multiple data packages.
The first package consists of 0x69 followed by 1023 times 0x00.
Then i receive the rest of the 55bytes.
This happens 70% of the time, sometimes the array get spiltted in the middle and sometimes the whole array is received complete.
Is this a normal Android-Bluetooth behavior
Thanks in advance...
private class ConnectedThread extends Thread {
private final BluetoothSocket mmSocket;
private final InputStream mmInStream;
private final OutputStream mmOutStream;
public ConnectedThread(BluetoothSocket socket) {
Log.d(TAG, "create ConnectedThread");
mmSocket = socket;
InputStream tmpIn = null;
OutputStream tmpOut = null;
// Get the BluetoothSocket input and output streams
try {
tmpIn = socket.getInputStream();
tmpOut = socket.getOutputStream();
} catch (IOException e) {
Log.e(TAG, "temp sockets not created", e);
}
mmInStream = tmpIn;
mmOutStream = tmpOut;
}
public void run() {
Log.i(TAG, "BEGIN mConnectedThread");
byte[] buffer = new byte[1024];
int bytes;
// Keep listening to the InputStream while connected
while (true) {
try {
// Read from the InputStream
bytes = mmInStream.read(buffer);
// Send the obtained bytes to the UI Activity
mHandler.obtainMessage(BluetoothChat.MESSAGE_READ, bytes, -1, buffer)
.sendToTarget();
} catch (IOException e) {
Log.e(TAG, "disconnected", e);
connectionLost();
break;
}
}
}

This answer here answered the same question. I just had a same issue and this answer was what I found.