目录1.绪论............................................................21.1频率计的概述...............................................21.2频率计的主要性能...........................................21.2.1.测试功能.............................................21.2.2.测量范围.............................................21.2.3.输入特性.............................................31.2.4.显示及工作方式.......................................31.2.5.输出.................................................32.课程设计要求.....................................................32.1课程设计的目的..............................................32.2课程设计的要求..............................................32.3方案论证....................................................43.实验原理.........................................................43.1测频法（定时1s测信号脉冲次数）............................43.2测周法....................................................54.实验内容及步骤...................................................64.1系统组成...................................................64.2AT89C51单片机及引脚的说明.................................74.3显示电路....................................................94.41s定时的实现..............................................104.5频率计量程的自动切换.......................................114.6程序构建与算法分析.........................................124.7仿真模型的构建.............................................135.电路仿真及PCB制作..............................................145.1电路仿真...................................................145.2PCB制作...................................................196.分析与总结......................................................206.1实验误差分析与改进.........................................206.2总结与心得体会.............................................217.参考文献........................................................22致谢.............................................................22附录（完整的源程序）...............................................231．1602_Drive.h完整的库函数...................................232．方法一的源程序..................................