Re: [pyusb-users] Installation problem on OSX 10.8 with Python 2.7

[Mathieu C. <mat...@gm...>]

Le 9/03/13 14:58, Wander Lairson Costa a écrit :
> 2013/3/9 Mathieu Carette <mat...@gm...>:
>> Hello,
>>
>> I am trying to get pyusb working on OSX 10.8 with Python 2.7 (my goal is
>> to be able to communicate with a novation nocturn using python, see
>> https://github.com/dewert/nocturn-linux-midi which relies on pyusb.)
>>
>> I installed libusb 1.0 through macports
>>
>> $ port installed libusb -v
>> The following ports are currently installed:
>>     libusb @1.0.9_0 (active)
>>     libusb @1.0.9_0+universal
>>
>> Now after installing pyusb (and setting PYUSB_DEBUG_LEVEL = debug), it
>> seems pyusb cannot find any backend :
>>
>>   >>> import usb
>>   >>> usb.core.find()
>> 2013-03-09 10:28:47,635 ERROR:usb.backend.libusb1:Error loading libusb
>> 1.0 backend
>> Traceback (most recent call last):
>>     File "/Library/Python/2.7/site-packages/usb/backend/libusb1.py", line
>> 655, in get_backend
>>       _lib = _load_library()
>>     File "/Library/Python/2.7/site-packages/usb/backend/libusb1.py", line
>> 205, in _load_library
>>       raise OSError('USB library could not be found')
>> OSError: USB library could not be found
>> 2013-03-09 10:28:47,636 ERROR:usb.backend.openusb:Error loading OpenUSB
>> backend
>> Traceback (most recent call last):
>>     File "/Library/Python/2.7/site-packages/usb/backend/openusb.py", line
>> 701, in get_backend
>>       _lib = _load_library()
>>     File "/Library/Python/2.7/site-packages/usb/backend/openusb.py", line
>> 248, in _load_library
>>       raise OSError('USB library could not be found')
>> OSError: USB library could not be found
>> 2013-03-09 10:28:47,638 ERROR:usb.backend.libusb0:Error loading libusb
>> 0.1 backend
>> Traceback (most recent call last):
>>     File "/Library/Python/2.7/site-packages/usb/backend/libusb0.py", line
>> 580, in get_backend
>>       _setup_prototypes(_lib)
>>     File "/Library/Python/2.7/site-packages/usb/backend/libusb0.py", line
>> 208, in _setup_prototypes
>>       lib.usb_open.argtypes = [POINTER(_usb_device)]
>>     File
>> "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/ctypes/__init__.py",
>> line 366, in __getattr__
>>       func = self.__getitem__(name)
>>     File
>> "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/ctypes/__init__.py",
>> line 371, in __getitem__
>>       func = self._FuncPtr((name_or_ordinal, self))
>> AttributeError: dlsym(RTLD_DEFAULT, usb_open): symbol not found
>> Traceback (most recent call last):
>>     File "<stdin>", line 1, in <module>
>>     File "/Library/Python/2.7/site-packages/usb/core.py", line 856, in find
>>       raise ValueError('No backend available')
>> ValueError: No backend available
>>
>>
>>
>> Could anyone point me to the next thing to do in this case (I did search
>> the mailing list and the internet, where similar issues where occuring,
>> but I could not find an answer explicit enough for me to understand what
>> to do: I am rather new to both OSX and Python)
>>
> After you install libusb, where does it reside?
>
>

I changed nothing from the default macports behavior. I am not quite 
sure what to look for.

The files libusb-1.0.0.dylib, libusb-1.0.a, libusb-1.0.la, ... which are 
located in /opt/local/lib/

Other than that, there are source files
/opt/local/include/libusb-1.0/libusb.h
/opt/local/var/macports/software/libusb/libusb-1.0.9_0.darwin_12.x86_64.tbz2