Re: [pyusb-users] [EXTERNAL] Re: "No backend available" error

[Ian D. <it....@gm...>]

Not sure what's wrong, and no easy way of telling
as dev.get_active_configuration() segfaults on OSX...

Do you know to what endpoint you're trying to write? What hardware's
attached? What functionality are you trying to expose?

On Tue, Nov 29, 2011 at 12:06, Barney, Bryson <bb...@sa...> wrote:

>  Ok, I installed the binary backend in addition to the Python bindings.
> Now it can find a backend, and I am pretty sure that it is finding my
> device as well.  When I run the script, it returns:****
>
> ** **
>
> <usb.core.Device object at 0x000000000251B080>****
>
> Traceback (most recent call last):****
>
>     File “usb_test.py”, line 17, in <module>****
>
>         interface_number = cfg[0].bInterfaceNumber****
>
>     File “C:\Python27\usb\core.py”, line 459, in __getitem__****
>
>         return Interface(self.device, index[0], index[1], self.index)****
>
> TypeError: ‘int’object is not sbuscriptable****
>
> ** **
>
> I am not sure how to solve this error.  All I want to do in the end is
> write the bytes 0x9F 0x02 0x05 and 0x01 to the device.  Any ideas on how to
> get past this?  Thanks for the help by the way.****
>
> ** **
>
> Thanks,****
>
> Bryson****
>
> ** **
>
> *From:* Ian Daniher [mailto:it....@gm...]
> *Sent:* Tuesday, November 29, 2011 10:18 AM
> *To:* pyu...@li...
> *Subject:* [EXTERNAL] Re: [pyusb-users] "No backend available" error****
>
> ** **
>
> Do you have LibUSB installed? You'll need a binary backend in addition to
> the Python bindings. ****
>
> ** **
>
> You can follow the installation instructions located at
> http://sourceforge.net/apps/trac/libusb-win32/wiki.****
>
> ** **
>
> On Tue, Nov 29, 2011 at 11:11, Barney, Bryson <bb...@sa...> wrote:*
> ***
>
> Hi,****
>
>  ****
>
> I am new here, and a new user of PyUSB.  I have a very simple HID
> Isochronous application to use this for, so I thought that I would start
> out by running the example that is shown in the “Programming with PyUSB
> 1.0” tutorial.  I am running this on windows 7 with python27****
>
>  ****
>
> I get through the following lines:****
>
>  ****
>
> import usb.core****
>
> import usb.util****
>
>  ****
>
> # find our device****
>
> dev = usb.core.find(idVendor=0xfffe, idProduct=0x0001)****
>
>  ****
>
> Then “ValueError: no backend abailable” appears, which is an error from
> line 846 in core.py.  It looks like I have all three backends (libusb01.py,
> libusb10.py, and openusb.py) in the usb/backend directory.  Do you by any
> chance know why it cannot find a backend?  Any help with this would be much
> appreciated.****
>
>  ****
>
> Thanks,****
>
> Bryson****
>
>  ****
>
> Just in case, here is the script that I am trying to run:****
>
>  ****
>
>  ****
>
> import usb.core****
>
> import usb.util****
>
>  ****
>
> # find our device****
>
> dev = usb.core.find(idVendor=0x0B40, idProduct=0x0133)****
>
>  ****
>
> # was it found?****
>
> if dev is None:****
>
>     raise ValueError('Device not found')****
>
>  ****
>
> # set the active configuration. With no arguments, the first****
>
> # configuration will be the active one****
>
> dev.set_configuration()****
>
>  ****
>
> # get an endpoint instance****
>
> cfg = dev.get_active_configuration()****
>
> interface_number = cfg[0].bInterfaceNumber****
>
> alternate_settting = usb.control.get_interface(interface_number)****
>
> intf = usb.util.find_descriptor(****
>
>     cfg, bInterfaceNumber = interface_number,****
>
>     bAlternateSetting = alternate_setting****
>
> )****
>
>  ****
>
> ep = usb.util.find_descriptor(****
>
>     intf,****
>
>     # match the first OUT endpoint****
>
>     custom_match = \****
>
>     lambda e: \****
>
>         usb.util.endpoint_direction(e.bEndpointAddress) == \****
>
>         usb.util.ENDPOINT_OUT****
>
> )****
>
>  ****
>
> assert ep is not None****
>
>  ****
>
> # write the data****
>
> ep.write('test')****
>
>  ****
>
>  ****
>
>  ****
>
>
>
> ------------------------------------------------------------------------------
> All the data continuously generated in your IT infrastructure
> contains a definitive record of customers, application performance,
> security threats, fraudulent activity, and more. Splunk takes this
> data and makes sense of it. IT sense. And common sense.
> http://p.sf.net/sfu/splunk-novd2d
> _______________________________________________
> pyusb-users mailing list
> pyu...@li...
> https://lists.sourceforge.net/lists/listinfo/pyusb-users****
>
> ** **
>
>
> ------------------------------------------------------------------------------
> All the data continuously generated in your IT infrastructure
> contains a definitive record of customers, application performance,
> security threats, fraudulent activity, and more. Splunk takes this
> data and makes sense of it. IT sense. And common sense.
> http://p.sf.net/sfu/splunk-novd2d
> _______________________________________________
> pyusb-users mailing list
> pyu...@li...
> https://lists.sourceforge.net/lists/listinfo/pyusb-users
>
>