I am using Qt (C++) on Linux and I wish to bypass Java entirely, using the .so files directly. Qt provides the activity for me, so I just need to call the native API from C++. (It's actually more work for me to use the Java API)
Where can I find the information on what API is exposed and has anyone done this previously?
If you installed using packages, just install the libphidget22dev package to get the phidget22.h header and dev files. If you installed with 'make install' those are already installed. Have a look at the C API and examples.
You could develop against the supplied native .so, you'll need to generate the phidget22.h header from our Linux source release. The Android USB code is implemented in Java (phidget22usb.jar) - so if you care about native USB, you'll need to at a minimum initialize USB from Java (or JNI).