python - PyUSB USBError: [Errno None] Unknown error -

i'm trying run set_configuration() method connect usb device receiving following error:

[errno none] unknown error traceback (most recent call last):   file "usb_ruf_test.py", line 74, in <module>     dev.set_configuration()   file "/usr/local/lib/python2.7/dist-packages/usb/core.py", line 819, in set_configuration     self._ctx.managed_set_configuration(self, configuration)   file "/usr/local/lib/python2.7/dist-packages/usb/core.py", line 129, in managed_set_configuration     self.backend.set_configuration(self.handle, cfg.bconfigurationvalue)   file "/usr/local/lib/python2.7/dist-packages/usb/backend/libusb1.py", line 786, in set_configuration     _check(self.lib.libusb_set_configuration(dev_handle.handle, config_value))   file "/usr/local/lib/python2.7/dist-packages/usb/backend/libusb1.py", line 592, in _check     raise usberror(_strerror(ret), ret, _libusb_errno[ret]) usberror: [errno none] unknown error 

this code i'm using:

import usb.core import usb.util import time import traceback  attempts = 0 dev = usb.core.find(idvendor=0x0ffd, idproduct=0xff00) while dev none:     attempts += 1     dev = usb.core.find(idvendor=0x0ffd, idproduct=0xff00)     print "(" + str(attempts) + " attempts) waiting 5 seconds before trying again..."     time.sleep(5)  print "connected " + str(dev)  try:     dev.set_configuration()     cfg = dev.get_active_configuration()      intf = cfg[(0,0)]      outputendpoint = usb.util.find_descriptor(intf, custom_match = lambda e: usb.util.endpoint_direction(e.bendpointaddress) == usb.util.endpoint_out)      message = reading_start_message()     print "\nmessage sent:", "\n\n", message, "\n"     outputendpoint.write( message )      print "received:\n"     good_reads_count = 0     result = dev.read(0x81, 2000, 5000)     while len(result) != 0:         good_reads_count += 1         print result.tostring()         result = dev.read(0x81, 2000, 5000)      print "good reads: " + str(good_reads_count)  except exception, e:     print("there error")     print e, traceback.format_exc()  print "disconnected" 

and device's usb info:

connected device id 0ffd:ff00 on bus 001 address 008 =================  blength                :   0x12 (18 bytes)  bdescriptortype        :    0x1 device  bcdusb                 :  0x200 usb 2.0  bdeviceclass           :    0x0 specified @ interface  bdevicesubclass        :    0x0  bdeviceprotocol        :    0x0  bmaxpacketsize0        :   0x40 (64 bytes)  idvendor               : 0x0ffd  idproduct              : 0xff00  bcddevice              :  0x100 device 1.0  imanufacturer          :    0x1 error accessing string  iproduct               :    0x2 error accessing string  iserialnumber          :    0x0  bnumconfigurations     :    0x1   configuration 1: 500 ma ==================================    blength              :    0x9 (9 bytes)    bdescriptortype      :    0x2 configuration    wtotallength         :   0x20 (32 bytes)    bnuminterfaces       :    0x1    bconfigurationvalue  :    0x1    iconfiguration       :    0x0    bmattributes         :   0x80 bus powered    bmaxpower            :   0xfa (500 ma)     interface 0: vendor specific ===========================      blength            :    0x9 (9 bytes)      bdescriptortype    :    0x4 interface      binterfacenumber   :    0x0      balternatesetting  :    0x0      bnumendpoints      :    0x2      binterfaceclass    :   0xff vendor specific      binterfacesubclass :    0x1      binterfaceprotocol :    0x1      iinterface         :    0x0       endpoint 0x81: bulk in ===============================        blength          :    0x7 (7 bytes)        bdescriptortype  :    0x5 endpoint        bendpointaddress :   0x81 in        bmattributes     :    0x2 bulk        wmaxpacketsize   :  0x200 (512 bytes)        binterval        :    0x0       endpoint 0x2: bulk out ===============================        blength          :    0x7 (7 bytes)        bdescriptortype  :    0x5 endpoint        bendpointaddress :    0x2 out        bmattributes     :    0x2 bulk        wmaxpacketsize   :  0x200 (512 bytes)        binterval        :    0x0 

i'm new pyusb, feel i'm following instructions github page. i'm running code on raspberry pi rasbian os. i'm using python 2.7.3 , running root. device has 1 configuration , 1 interface doing wrong?