Hello!
I try to connect device (STM32-Nucleo) with PC via USB.
I have downloaded Qt-5.7.0 with MinGW-5.3.0 and libusb-1.0.20.

(folders of libusb-1.0.20)
Qt Code: 
  1. libusb-1.0.20
  2.     examples
  3.     include
  4.         libusb-1.0
  5.             libusb.h
  6.     MinGW32
  7.         dll
  8.             libusb-1.0.dll
  9.             libusb-1.0.dll.a
  10.         static
  11.             libusb-1.0.a
  12.     MinGW64
  13.     MS32
  14.     MS64
  15.     libusb-1.0.def
  16.     README.txt
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1. I have created an empty project
2. added to .pro
Qt Code: 
  1. INCLUDEPATH += C:\Qt\libusb-1.0.20\include\libusb-1.0\
  2. LIBS += C:\Qt\libusb-1.0.20\MinGW32\static\libusb-1.0.a
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3. added to main.cpp
Qt Code: 
  1. #include <libusb.h>
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(then autosubstitution showed functions from libusb)

4. added call of libusb_init(NULL);
Qt Code: 
  1. int main(int argc, char *argv[])
  2. {
  3.     libusb_init(NULL);
  4.  
  5.     QApplication a(argc, argv);
  6.     MainWindow w;
  7.     w.show();
  8.  
  9.     return a.exec();
  10. }
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But. There is an error
In function `Z5qMainiPPc':
undefined reference to `libusb_init@4'

Can someone tell me where I'm going wrong?