Not too sure about that problem. I have only been running on Linux, so I have not had much practice getting qextserialport to compile in windows.
One guy told me changed the win32 section in the .pro file as follows to get it to compile on windows:
win32:{
DEFINES = _TTY_WIN_
# SOURCES += qextserialport/src/win_qextserialport.cpp
DEFINES += WINVER=0x0501 # needed for mingw to pull in appropriate dbt business...probably a better way to do this
LIBS += -lsetupapi
LIBS +=D:\qt\4.7.3\demos\qextserialport\src\build\qextserialport1.dll
}I found a guide here that looks promising:
http://www.qtcentre.org/threads/32830-HowTo-use-QextSerialPort-classes