Hi Lesiok,
I know Qt is not a magic, but I am a beginner and not an advanced user like you. I only needed some help to understand how Qt is working with the USB libraries.
Now I got it, after 3 weeks looking for the information in internet, doing some Qt video tutorials and reading some USB communication books.
I would like to tell you thank you, but you were not helping me.

USB communication is not easy and there are not a lot of examples for the beginners like me. The USB 2.0 specification has 650 pages!!!!
There are also not information how to get working the USB libraries inside Qt.

My recommendations to help someone are:

- Video-Tutorials in youtube to learn Qt: https://youtu.be/6KtOzh0StTc

- Examples to work with Qt and libusb (thanks google to help me to translate them!!!):
1. Japanese tutorial: http://www.cnblogs.com/lknlfy/tag/US...D%A6%E4%B9%A0/
2. Russian tutorial with Code: http://we.easyelectronics.ru/khomin/...n-proekta.html
3. Video example STM32, libusb & Qt (it is not complete, because you do not have all the code. But you can have the idea, how is working): https://youtu.be/EoE8QPeApxk

- Internet USB Information:
1. USB made simple: http://www.usbmadesimple.co.uk/
2. Embedded USB - a brief tutorial : http://www.computer-solutions.co.uk/...b_tutorial.htm
3. USB in a Nutshell: http://www.beyondlogic.org/usbnutshell/usb1.shtml

- I read some german books about USB:
1. Messen und Steuern mit USB und C++ (with some Qt examples).
2. USB 2.0, Handbuch für Entwickler.

Regards
Vero