嘿,我正在尝试运行教程中提供的简单脚本;。USB正在导入,但是当我尝试搜索设备时出现以下错误,请帮助
>>> dev=usb.core.find()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "C:\Python27\lib\site-packages\usb\core.py", line 819, in find
raise ValueError('No backend available')
ValueError: No backend available