Hi,

I'm getting the no backend detected error (well it did work once but I couldn't get it work again).  This is on Mavericks 10.9.2, libusb-1.0.9, and pyusb-1.0.b.1. There weren't any obvious install errors. I tried export PYUSB_DEBUG_LEVEL=debug, but it only seems to output more after calling usb.core.find() a second time?  (and nothing extra from the command line even setting the file output) Output is below.  Listing devices using the libusb example works fine so I think that's installed right.  Any ideas?

Thanks,
Jen

In [1]: import usb


In [2]: usb.core.find()

---------------------------------------------------------------------------

ValueError                                Traceback (most recent call last)

<ipython-input-2-acfe6f4fcfac> in <module>()

----> 1 usb.core.find()


/Library/Python/2.7/site-packages/usb/core.pyc in find(find_all, backend, custom_match, **args)

    862                 break

    863         else:

--> 864             raise ValueError('No backend available')

    865 

    866     k, v = args.keys(), args.values()


ValueError: No backend available


In [3]: usb.core.find()

---------------------------------------------------------------------------

AttributeError                            Traceback (most recent call last)

<ipython-input-3-acfe6f4fcfac> in <module>()

----> 1 usb.core.find()


/Library/Python/2.7/site-packages/usb/core.pyc in find(find_all, backend, custom_match, **args)

    870     else:

    871         try:

--> 872             return _interop._next(device_iter(k, v))

    873         except StopIteration:

    874             return None


/Library/Python/2.7/site-packages/usb/_interop.pyc in _next(iter)

     58 def _next(iter):

     59     try:

---> 60         return next(iter)

     61     except NameError:

     62         return iter.next()


/Library/Python/2.7/site-packages/usb/core.pyc in device_iter(k, v)

    838 

    839     def device_iter(k, v):

--> 840         for dev in backend.enumerate_devices():

    841             d = Device(dev, backend)

    842             if  _interop._reduce(


/Library/Python/2.7/site-packages/usb/backend/libusb0.pyc in enumerate_devices(self)

    396     @methodtrace(_logger)

    397     def enumerate_devices(self):

--> 398         _check(_lib.usb_find_busses())

    399         _check(_lib.usb_find_devices())

    400         bus = _lib.usb_get_busses()


/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/ctypes/__init__.pyc in __getattr__(self, name)

    376         if name.startswith('__') and name.endswith('__'):

    377             raise AttributeError(name)

--> 378         func = self.__getitem__(name)

    379         setattr(self, name, func)

    380         return func


/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/ctypes/__init__.pyc in __getitem__(self, name_or_ordinal)

    381 

    382     def __getitem__(self, name_or_ordinal):

--> 383         func = self._FuncPtr((name_or_ordinal, self))

    384         if not isinstance(name_or_ordinal, (int, long)):

    385             func.__name__ = name_or_ordinal


AttributeError: dlsym(RTLD_DEFAULT, usb_find_busses): symbol not found