import usb.core if __name__ == "__main__": dev = usb.core.find(idVendor=0xcafe, idProduct=0xcafe) if dev is None: raise ValueError('Device not found') dev.set_configuration() import gtk w = gtk.Window() w.connect("destroy", gtk.main_quit) toggle = gtk.ToggleButton("Toggle LED") def toggled(button): dev.ctrl_transfer(0x40, 0, button.get_active(), 0, 'Hello World!') toggle.connect("toggled", toggled) w.add(toggle) w.show_all() gtk.main()