Qt Bluetooth keeps on "Connecting state"

[Manu_NaFu]

Hello,

I bought a HM-10 bluetooth module and would like to connect it with an arduino uno board to my pc. I tried connecting it to my phone with an app called "serial bluetooth terminal" and it works, but when I try to connect to my ubuntu pc, it hangs in the "ConnectingState" and never connects.

I don't really know what uuid to use, I just found this one on the internet but is not working for me:

static const QString serviceUuid(QStringLiteral("00001101-0000-1000-8000-00805F9B34FB"));
socket->connectToService(QBluetoothAddress(string), QBluetoothUuid(serviceUuid), QIODevice::ReadWrite);

If you need more code I can post anything.

Many thanks in advance.

[mrjj]

Hi
Did you try any of the samples and see if they see it ?
https://doc.qt.io/qt-5/qtbluetooth-btscanner-example.html

[Manu_NaFu]

@mrjj Hi, thanks for your response. I can see a lot of examples but none for bluetooth.

The thing is that I can see the bluetooth but when I click to connect, it keeps on "connecting state". I'm trying to use the low energy API now as the module HM-10 is low energy as well, and see if that works.

[mrjj]

@Manu_NaFu

Hi

• I can see a lot of examples but none for Bluetooth.
  you mean in creator ?

On Linux, it uses BlueZ as a backend.

you could also try the command line utility
bluetoothctl
and see if that can pair to it.

https://ubuntu.com/core/docs/bluez/reference/commands
https://www.makeuseof.com/manage-bluetooth-linux-with-bluetoothctl/

[Manu_NaFu]

@mrjj Thanks a lot, this information is useful indeed.

I have followed the steps but I'm still missing something, when I try to pair, I get:

[CHG] Device <mac addres> Connected: yes
Failed to pair: org.bluez.Error.AuthenticationFailed
[CHG] Device <mac addres> Connected: no

Do you have any clue why this happens? I used trust <mac addres> and pair <mac addres>

I know this is not related to Qt anymore, but if you have any clue that would be much appreciated.

Thanks again for your support.

[Manu_NaFu]

@mrjj Hi Again,

I just noticed that despite not being able to pair, I can connect to the bluetooth module using connect (in bluetoothctl).

Could it be that Qt internally always tries to pair before connect, and that's why it cannot connect?