本频率计采用数据选择器实现对任意周期信号的频率、周期、脉宽、占空比、自检等不同功能输入电路的选择，通过键盘实现了各个功能的选择，最后采用LED动态显示模块将所测的数值显示出来。-The frequency meter data selector realize periodic signal of arbitrary frequency, period, pulse width, duty cycle, different functions such as self-selection of