C code for the virture.

ARM的P0.0口接LED，串口接Proteus的虚拟终端。每隔一段时间改变一次LED的状态，并且在串口上输出LED的当前状态。-LED contact the port P0.0,and uart port contact the Proteus virture terminal . alter the LED state every a time,and output the curent state to the termial.

USB做虚拟串口例子代码，包含AT指令集，-USB for Virture COM