该代码是针对超声波FSK模式测距在proteus下的仿真研究，利用LPC2114实现调制解决，主要难度是解FSK信号变化时刻，实现高精度测距。-The code is a FSK mode of ultrasonic ranging in proteus simulation under study, the modulation using LPC2114 to solve the main difficulty is to expl