关于楼主在3楼的问题,请参考下面的状态图,这在USB DFU文本的第28页,你所列出的那段程序,漏掉了关键的部分,就是之前的case语句,根据这个语句,这里是处理DNLOAD_SYNC状态,即下图中的状态3;再结合该GETSTATUS函数的功能,根据USB DFU文本的第20页中第6.1.2节,这个时间被定义为:Minimum time, in milliseconds, that the host should wait before sending a subsequent DFU_GETSTATUS request. (The purpose of this field is to allow the device to dynamically adjust the amount of time that the device expects the host to wait between the status phase of the next DFU_DNLOAD and the subsequent solicitation of the device’s status via DFU_GETSTATUS. This permits the device to vary the delay depending on its need to erase memory, program the memory, etc.)