Qt5.2 beta bluetooth exams good working on android ?

[liangliang]

i made a demo form the Qt help ( Bluetooth Chat Example),and i use two phones ( android) to test them ,but they can not connect ,so i think maybe the qt bluetooth do not support android .

[SGaist]

Hi,

Current state of bluetooth is given "here":http://blog.qt.digia.com/blog/2013/09/30/qt-5-2-alpha-available/

And the relevant bug to follow is "QTBUG-33792":https://bugreports.qt-project.org/browse/QTBUG-33792

[XelaG]

According to KDab, Bluetooth might be supported in Qt 5.3.
"Qt Android":http://www.kdab.com/qt-on-android-episode-1/

[s.frings74]

I dont want to wait for Qt 5.3, therefore I found a way to access the Java Bluetooth API via JNI.

http://stefanfrings.de/android_qt/index-en.html

It seems that Qt 5.3 contains a very similar approach. The main difference seems to be that Qt 5.3 recieves data in a separate thread and signals reception with a signal. My class works with polling, the application has to check repeatedly, if something has been received.

[JKSH]

[quote author="s.frings74" date="1398153323"]I dont want to wait for Qt 5.3, therefore I found a way to access the Java Bluetooth API via JNI.

http://stefanfrings.de/android_bluetooth/index-en.html

It seems that Qt 5.3 contains a very similar approach. The main difference seems to be that Qt 5.3 recieves data in a separate thread and signals reception with a signal. My class works with polling, the application has to check repeatedly, if something has been received.
[/quote]Hi Steve, thank you for sharing your solution!

Note that you don't have to wait. The Qt 5.3 beta is already available: http://download.qt-project.org/development_releases/qt/5.3/5.3.0-beta/ (The Release Candidate will be out this coming Thursday)

[s.frings74]

Oops, so I wasted a weekend :-)
At least I learnt a bit about JNI.

[uusitalo]

This is what im looking for but cant get it connect to arduino.
Im using QT 5.3 Beta

@W/System.err( 9490): java.io.IOException: read failed, socket might closed or timeout, read ret: -1
W/System.err( 9490): at android.bluetooth.BluetoothSocket.readAll(BluetoothSocket.java:569)
W/System.err( 9490): at android.bluetooth.BluetoothSocket.readInt(BluetoothSocket.java:580)
W/System.err( 9490): at android.bluetooth.BluetoothSocket.connect(BluetoothSocket.java:321)
W/System.err( 9490): at dalvik.system.NativeStart.run(Native Method)
E/Qt ( 9490): ../Mittari/androidrfcomm.cpp:33 (void AndroidRfComm::check(const char*)): Exception in BluetoothSocket.connect()
E/Qt ( 9490): ../Mittari/androidrfcomm.cpp:161 (void AndroidRfComm::connect(const QString&)): Cannot connect to the bluetooth device
D/Qt ( 9490): fontdatabases/basic/qbasicfontdatabase.cpp:238 (static QStringList QBasicFontDatabase::addTTFile(const QByteArray&, const QByteArray&)): FT_New_Face failed with index 0 : 90@

[s.frings74]

I would try to test the connection with a plain Java program. Then you know if there is an issue with the C++ part or a problem in the underlying Java interface.

I would also try to use another program first, for example "Bluetooth SPP" (the older 1.x version, version 2 runs unstable).

By the way: Why do you use my class with Qt 5.3? You dont need it!

[uusitalo]

Because i dont know how to code but i need to make simple android <-> hc-06 bluetooth program that reads numbers from arduino and displays them and can send terminal commands to it.

I made one version with eclipse but it doesnt work on other phones than samsung, dont know why.

And i am thinking that qt is best language fir coding because its multiplatform.

I tried to study bluetooth coding from chat example but its just too complex

[s.frings74]

Yes, the bluetooth classes of Qt are a bit more difficult. The use asynchronous callbacks to indicate received data. Also openng a connection is a bit more difficult. You have to search the arduino first and then you have the object needed to open a connection.

Anyway,check first if you have the same connection problems in Java. Create a new project with an empty activity. then insert the following lines into the end of MainActivity.onCreate() method:

@
try {
BluetoothAdapter adapter=BluetoothAdapter.getDefaultAdapter();
Set<BluetoothDevice> pairedDevices=adapter.getBondedDevices();
Iterator<BluetoothDevice> iterator=pairedDevices.iterator();

while (iterator.hasNext()) {
 BluetoothDevice device=iterator.next();
 Log.w(this.getClass().getSimpleName(),"Found "+device.getAddress()+" = "+device.getName());
 
 // Check for my Ardunio either by address or name
 // if device.getAddress().equals("20:13:11:15:16:08")) {
 if (device.getName().equals("HC-06")) { 
  BluetoothSocket socket=device.createRfcommSocketToServiceRecord(UUID.fromString("00001101-0000-1000-8000-00805F9B34FB"));
  socket.connect();
  InputStream istream=socket.getInputStream();
  OutputStream ostream=socket.getOutputStream();
  ostream.write("whatever you want to send\n".getBytes());
  ostream.flush(); // seems to be not neccessary

  Thread.sleep(1000);
  int avail=istream.available();
  Log.w(this.getClass().getSimpleName(),"Received "+avail+" bytes");
  
  BufferedReader br = new BufferedReader(new InputStreamReader(istream));
  String s=br.readLine();
  Log.w(this.getClass().getSimpleName(),"Received: "+s);
 }

}

}
catch(Exception e) {
e.printStackTrace();
}
@

Are you sure that you entered the correct device address? Every Bluetooth module has its own unique address.

[s.frings74]

I found a bug in androidrfcomm.cpp:
@
if (address.compare(adr.toString(),Qt::CaseInsensitive)) {...}
@
Must be changed to
@
if (address.compare(adr.toString(),Qt::CaseInsensitive)==0) {...}
@

Otherwise it would attempt to connect to the first bluetooth devcie that is reachable. May that's your problem cause.

[uusitalo]

i do have java version working, but i dont want to make my app with java its just too complicated.

but thats just what im trying to do and when i can do it in qt its easy to customise in my way

i made motorcycle speedometer with eclipse but i still have few issues with keeping bluetooth state when changing orientation

[s.frings74]

I just uploaded an improved version of the class.
The isTimeout() function did not work as planned, and you can now connect by device address or name.
I also added an example program.

[JKSH]

[quote author="s.frings74" date="1398174767"]Oops, so I wasted a weekend :-)
At least I learnt a bit about JNI.[/quote]I don't think that's wasted -- learning more about your target platform is always useful. :)