网络上下载了好多STM32F105USB_Hout的程序，结果都各种问题枚举不成功。一下决心，逐步查阅，修改晶振等相关信息，退掉例程中的LCD程序，精简。亲测可用。注意，使用之前，请U盘之前格式化。注：晶振是常用的8M晶振。-The network to download a lot of STM32F105 USB Host program, the results are unsuccessful enumerate various issues. A determined, progres