尝试在pyusb中调用后端模块时出错." AttributeError:“模块"对象没有属性“后端"" [英] Error trying to call the backend module in pyusb. "AttributeError: 'module' object has no attribute 'backend'"

问题描述

我最近为此项目安装了pyusb，该项目试图尝试写入 USB LED消息登上，并收到此错误:

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:模块"对象没有属性后端"

我不知道为什么，我检查了pyusb模块文件，它显然有一个名为"backend"的文件夹.并且里面有正确的文件.

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.

这是我所有的代码:

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')

要关注的代码:

backend = usb.backend.libusb01.get_backend(find_library=lambda C: "Users\absolute\Desktop\libusb-win32-bin-1.2.6.0\lib\msvc_x64")

我在其他代码中也注意到人们根本没有后端.但是，当我尝试删除代码的后端部分时，它将显示:

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

一些额外的信息:

• Windows 8 64位
• Python 2.7
• pyusb-1.0.0a2

推荐答案

我知道这个问题已有4个月了，但是如果有帮助，我认为您缺少导入声明:

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

请参见 https://github.com/walac/pyusb/blob/master/docs/tutorial.rst#specifying-libraries-hand 了解详情.

这篇关于尝试在pyusb中调用后端模块时出错." AttributeError:“模块"对象没有属性“后端""的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！