Develop Reference

Bluetooth: How to connect to any device

The Bluetooth tutorials i read all mentioned that i need to have the same UUID on both sides (Server and Client) to establish a connection between two devices. But what if i dont know the UUID of my Client and if i dont care?
Background information: I have over 1000 microcontrollers with bluetooth. Each microcontroller has a fix and unchangeable UUID. Smartphones should be able to send string messages to that micrcontrollers (single connection, one smartphone is controlling one microcontroller). It should not matter which Smartphone is controlling which microcontroller. So in fact i really dont care about the UUID of the Client.
So my Smartphone is the Server and is opening a listening thread for incoming Bluetooth connections but i have to put in a UUID here:
tempBluetoothServerSocket = bluetoothAdapter.listenUsingRfcommWithServiceRecord(NAME, MY_UUID);
But when i have thousand different UUID's and i really dont care about the UUID what should i put in there? Also the BluetoothSocket:
tempBluetoothSocket = this.bluetoothDevice.createRfcommSocketToServiceRecord(MY_UUID);
How to know which UUID?
So the core question is: How can i connect to any microcontroller?

I've been using this:
// Unique UUID for this application
private static final UUID UUID_ANDROID_DEVICE =
UUID.fromString("fa87c0d0-afac-11de-8a39-0800200c9a66");
private static final UUID UUID_OTHER_DEVICE =
UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
And it's uses:
public AcceptThread(boolean isAndroid) {
BluetoothServerSocket tmp = null;
// Create a new listening server socket
try {
if(isAndroid)
tmp = mAdapter.listenUsingRfcommWithServiceRecord(NAME_SECURE, UUID_ANDROID_DEVICE);
else
tmp = mAdapter.listenUsingRfcommWithServiceRecord(NAME_SECURE, UUID_OTHER_DEVICE);
} catch (IOException e) { }
mmServerSocket = tmp;
}
public ConnectThread(BluetoothDevice device) {
mmDevice = device;
BluetoothSocket tmp = null;
// Get a BluetoothSocket for a connection with the
// given BluetoothDevice
try {
if(BluetoothService.this.isAndroid)
tmp = device.createRfcommSocketToServiceRecord(UUID_ANDROID_DEVICE);
else
tmp = device.createRfcommSocketToServiceRecord(UUID_OTHER_DEVICE);
} catch (IOException e) { }
mmSocket = tmp;
}
Which allows my devices to connect to any bluetooth device I've tested with. For the sake of testing, it has only been varying bluetooth barcode scanners. Although I believe this is a generic RFCOMM UUID.
It hasn't failed me yet.

Bluetooth socket only returns null. Android Bluetooth

Iam trying to connect to a socket by using the connect method. Iam generating a String containing the UUID like this:
MY_UUID = UUID.fromString("45341da0-c9c1-11e1-9b21-0800200c9a66");
Then constructing a BluetoothSocket like this:
BluetoothSocket tmp = null;
I also want to connect to a specific device by its mac-address:
BluetoothDevice device = BluetoothAdapter.getDefaultAdapter().getRemoteDevice("00:1B:DC:0F:EC:7E");
and then making the bluetoothSocket
try {
tmp = device.createInsecureRfcommSocketToServiceRecord(MY_UUID);
} catch (IOException e) {
Toast.makeText(getApplicationContext(), "Exception1: " + e.getMessage(), Toast.LENGTH_LONG).show();
}
Just for to test I added a breakpoint where the tmp object is been initialized inside the try catch. But it's only containing NULL The remote device does support OBEX OPP, but this is just a layer above the RFCOMM in the bluetooth stack, so I think my device should support RFCOMM for connections. Can anybody tell me why my tmp object is set to null?
Is there anyway I can test whenever the socket is created?

Issue with Bluetooth Device pairing

I am developing one simple Bluetooth application where I want to send a text message. Facing issues when trying to pair the devices, it throws exception “java.io.IOException: Service discovery failed”. For more details I am posting code herewith.
Ported application on LG phone Android version 2.3.3
private static final UUID MY_UUID = UUID.fromString("00000003-0000-1000-8000-00805F9B34FB");
BluetoothDevice btDevice = BluetoothActivity.btDevices.get(position).getBtDevice();
clientSocket = btDevice.createRfcommSocketToServiceRecord(MY_UUID);
//Method m = btDevice.getClass().getMethod("createRfcommSocketToServiceRecord", new Class[] { UUID.class } );
//clientSocket =(BluetoothSocket) m.invoke(btDevice, MY_UUID);
//Method m = btDevice.getClass().getMethod("createRfcommSocket",new Class[] { int.class });
//clientSocket =(BluetoothSocket) m.invoke(btDevice, 1);
if(clientSocket!=null)
{
if(BluetoothActivity.btAdapter.isDiscovering()){
BluetoothActivity.btAdapter.cancelDiscovery();
}
//facing issue during paring
clientSocket.connect();
tmpOut = clientSocket.getOutputStream();
tmpOut.write("HelloWorld.txt".getBytes());
if(tmpOut!=null){
tmpOut.close();
}
}
Any kind of help is appreciated,

Try using this UUID:
fa87c0d0-afac-11de-8a39-0800200c9a66
for some reason, this was the only UUID I could ever get to work... I have no idea why.

Bluetooth issues on HTC hero

I've written an android application getting data from external sensors using Bluetooth. It's working fine on Sony Ericsson XPERIA but not on a HTC Hero (it finds external devices but it can't get any data from them) I'm wondering why. After some research on the net, I still haven't found any clue.
Anyone had similar bluetooth issues on HTC?

you can make it like this:
private final String PBAP_UUID = "0000112f-0000-1000-8000-00805f9b34fb"; //standard pbap uuid
mSocket = mDevice.createInsecureRfcommSocketToServiceRecord(ParcelUuid.fromString(PBAP_UUID).getUuid())
mSocket.connect();
Just do it.

If I remember correctly the HTC phones had or [have] an issue at a certain API level (maybe 2.1 and below?). The resolution is reflection.
Reference
Disconnect a bluetooth socket in Android
Service discovery failed exception using Bluetooth on Android
Solution
Instead of using
tmp = device.createRfcommSocketToServiceRecord(MY_UUID);
use
Method m = device.getClass().getMethod("createRfcommSocket", new Class[] {int.class});
tmp = (BluetoothSocket) m.invoke(device, 1);
to get your BluetoothSocket on certain HTC phones using a certain API level.
Solution Expanded
I recently had an application where I had to account for this, and I did not like using this on non-HTC phones, so I had a conditional to check for HTC, if true then use reflection, otherwise dont.
public BTConnectThread(BluetoothDevice device) {
mmDevice = device;
BluetoothSocket tmp = null;
// Get a BluetoothSocket for a connection with the given BluetoothDevice
if (isAnHTCDevice())
{
try
{
Method m = device.getClass().getMethod("createRfcommSocket", new Class[] {int.class});
tmp = (BluetoothSocket) m.invoke(device, Integer.valueOf(1));
}
catch (Exception e)
{
Log.e(BCTAG, "Error at HTC/createRfcommSocket: " + e);
e.printStackTrace();
handler.sendMessage(handler.obtainMessage(MSG_BT_LOG_MESSAGE, "Exception creating htc socket: " + e));
}
}
else
{
try
{
UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
tmp = device.createRfcommSocketToServiceRecord(MY_UUID);
} catch (Exception e)
{
Log.e(BCTAG, "Error at createRfcommSocketToServiceRecord: " + e);
e.printStackTrace();
handler.sendMessage(handler.obtainMessage(MSG_BT_LOG_MESSAGE, "Exception creating socket: " + e));
}
}
mmSocket = tmp;
}
isAnHTCDevice():
public boolean isAnHTCDevice()
{
String manufacturer = android.os.Build.MANUFACTURER;
if (manufacturer.toLowerCase().contains("htc"))
return true;
else
return false;
}

you can make it like this:
private final String PBAP_UUID = "0000112f-0000-1000-8000-00805f9b34fb"; //standard pbap uuid
mSocket = mDevice.createInsecureRfcommSocketToServiceRecord(ParcelUuid.fromString(PBAP_UUID).getUuid());
mSocket.connect();
Just do it.

Android Bluetooth COM port

I have spent some time researching Android's ability to communicate with bluetooth devices that are designed to communicate over a Bluetooth COM port on a PC. I haven't been able to find a definitive answer, so I thought I'd ask here. I want to make sure that this is possible with Android.
I am new to Bluetooth communications, but the research I've done so far lead me to RFCOMM which somewhat sounded like what I wanted. Unfortunately, I'm still unable to confirm that this is in fact possible.
Any help/resources on this would be greatly appreciated.

Yes, Android can connect to Bluetooth COM ports on PC's. I am currently developing such an application. Here is a code example (Ite requires the bluetooth permissions te be set in the Manifest.xml file):
<uses-permission android:name="android.permission.BLUETOOTH" />
Java:
BluetoothAdapter adapter = BluetoothAdapter.getDefaultAdapter();
if (adapter == null) {
// Device does not support Bluetooth
finish(); //exit
}
if (!adapter.isEnabled()) {
//make sure the device's bluetooth is enabled
Intent enableBluetooth = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBluetooth, REQUEST_ENABLE_BT);
}
final UUID SERIAL_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB"); //UUID for serial connection
mac = "00:15:83:3D:0A:57"; //my laptop's mac adress
device = adapter.getRemoteDevice(mac); //get remote device by mac, we assume these two devices are already paired
// Get a BluetoothSocket to connect with the given BluetoothDevice
BluetoothSocket socket = null;
OutputStream out = null;
try {
socket = device.createRfcommSocketToServiceRecord(SERIAL_UUID);
} catch (IOException e) {}
try {
socket.connect();
out = socket.getOutputStream();
//now you can use out to send output via out.write
} catch (IOException e) {}