文档介绍：数字频率计是数字电路中的一个典型应用，实际的硬件设计用到的器件较多，而且会产生 比较大的延时，造成测量误差、可靠性差。传统的数字频率计一般是由分离元件搭接而成，随 着单片机的大规模的应用，单片机在频率测量方面也越来越多的被使用。在本课题中使用的 AT89S51这种低功耗,高性能CMOS 8位单片机系列的单片机的出现，具有更好的稳定性，更 快和更准确的运算精度，推动了工业生产，影响着人们的工作和学****而本次设计就是要通过 以AT89S51单片机为控制核心，实现对信号频率进行准确计数的设计。
单片机是将微型计算机的基本功能部件全部集成在一块半导体电路芯片上，具有功能强、 体积小、价格低、稳定可靠、研制周期短等优点，具有广阔的应用前景。本次毕业设计以ATMEL 公司的AT89S51单片机为核心，实现频率计数功能。频率计装置由单片机系统模块，LED显示 模块、MAX232串口通信模块组成，实现对频率进行测试并在LED显示出来。
本次毕业设计基于AT89S51单片机的频率计装置，设计sch电路原理图，并根据原理图完 成硬件部分的制作，采用KEIL-51单片机应用系统编制C语言系统程序，最后通过综合调试， 能实现所有要求的功能，完全满足本次毕业设计的要求。
关键词：频率计；单片机；LED显示；MAX232；定时器/计数器
Abstract
The digital frequency meter is in a digital circuit model application, the actual hardware design uses component more, moreover can have the quite big time delay, creates the measuring error, the reliability is bad. The traditional digital frequency meter generally is becomes byseparative element joining, along with the monolithic integrated circuit large-scale application, the monolithic integrated circuit more and more are also many in the frequency measurement aspect is used. AT89S51 this kind of low power loss uses which in this topic, high performance CMOS 8 monolithic integrated circuits series monolithic integrated circuit appearance, has a better stability, is quick% and the more accurate operation precision, impelled the industrial production, is interfering with people's work and the study. But this design is must through take the AT89S51 monolithic integrated circuit as the control core, realizes design which carries on to the signalling frequency accurately counts.
The monolithic integrated circuit is completely integrates the microcomputer basic function part on together the semiconductor electric circuit chip, has the function strongly, the volume small, the price low, stable reliable, the development cycle is short and soon the merit, has the broad application prospect. This graduation project take ATMEL Corporation's AT89S51 monolithic integrated circuit as the core, the realizati