USB51S库一共有3个文件，包括USB51S.LIB，ISR.C，ISR.H（为了增加USB通信的灵活性，并没有把所有的子程序都封装倒USB51S.LIB，而是在ISR.C建立部分通信程序，这样方便用户修改-USB51S for a total of three documents, including USB51S.LIB, ISR.C, ISR.H (USB communication in order to increase the flexibility, and not all th