问题
I recently installed pyusb for this project, which is trying to attempt at writing to a USB LED Message Board and received this error:
AttributeError: 'module' object has no attribute 'backend'
I don't know why this is, I checked the pyusb module files and it clearly has a folder named "backend" and inside has the correct files.
Here's all of my code:
import usb.core
import usb.util
import sys
backend = usb.backend.libusb01.get_backend(find_library=lambda C: "Users\absolute\Desktop\libusb-win32-bin-1.2.6.0\lib\msvc_x64")
#LED Display Message device identify
MessageDevice = usb.core.find(idVendor=0x1D34, idProduct=0x0013, backend=backend)
if MessageDevice is None:
raise ValueError('LED Message Display Device could not be found.')
MessageDevice.set_configuration()
# get an endpoint instance
cfg = MessageDevice.get_active_configuration()
interface_number = cfg[(0,0)].bInterfaceNumber
print interface_number
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('\x00\x06\xFE\xBA\xAF\xFF\xFF\xFF')
Code to focus on:
backend = usb.backend.libusb01.get_backend(find_library=lambda C: "Users\absolute\Desktop\libusb-win32-bin-1.2.6.0\lib\msvc_x64")
Also I've noticed in other code people don't have the backend at all. But when I try to remove the backend part of my code it displays:
MessageDevice = usb.core.find(idVendor=0x1D34, idProduct=0x0013)
File "C:\Python27\lib\site-packages\usb\core.py", line 846, in find
raise ValueError('No backend available')
ValueError: No backend available
Some extra info:
- Windows 8 64bit
- Python 2.7
- pyusb-1.0.0a2
回答1:
I know this question is 4 months old, but in case it helps I think you're missing an import statement:
import usb.backend.libusb1
See https://github.com/walac/pyusb/blob/master/docs/tutorial.rst#specifying-libraries-by-hand for more details.
来源:https://stackoverflow.com/questions/22273100/error-trying-to-call-the-backend-module-in-pyusb-attributeerror-module-obje