51单片机的串口中断演示程序，发送的字符可以在液晶屏上显示出来，同时可以接收单片机回送的字符，程序编译后，会出现警告提示，是由于有未调用的函数和有被多个程序调用的函数，在此不影响实验

结果，暂可不用去理会。（可以通过屏蔽未调用的函数和把被多个程序调用的函数设为再入函数来解决）-51 single-chip serial port interrupt demo program, sending the characters can be displayed on the LCD screen, single-chip microcomputer can receive at the same time the characters return, the program compiled, a warning prompt will appear, is not due to a function call and was a function of a number of procedure calls, in this does not affect the experimental results, there is no need to care about suspense. (Can not call a function of shielding and the number of procedures have been set to call a function of re-entry function to solve)