USB设备在正常工作以前,第一件要做的事就是枚举.枚举就是让HOST认得这个设备,并且为该设备准备其所请求的资



源,建立好主机和 设 备之间的信息沟通机制.

USB 枚举是一系列有序而又连贯的过程,哪怕只有一丝丝请求或者自报家门时出错,甚至于在规定的时间内答不上来



,设备就会被停机.枚举自然就不会成功.

-USB devices work properly before, the first thing to do is to enumerate. Enumeration is for HOST recognize the device and equipment to prepare their requests for resources, the establishment of good information between the host and device communication mechanism. USB enumeration is a series of orderly and coherent process but, even if only a trace request or Zibaojiamen error, even within the stipulated time and could not answer, the device is shut down. enumerate naturally will not be successful .