频率计设计

文档编号:DQ086   文档字数:11938,页数:38

摘    要
 
 本文基于STC89C51RC单片机，通过倍频技术将低频搬移至高频，然后再用计数法进行测频，实现了一个测量范围为0.01HZ~1MHZ、精度为1/100的频率计。该频率计只需外接几个阻容器件和供微控制器工作时钟的晶体振荡电路，就可实现频率测量功能,具有硬件简单、体积小、容易实现的特点。可直接驱动液晶显示器显示频率。整个电路采用5V直流供电，功耗低，便于制作便携式测量设备。

关键词：测频；STC89C51RC；倍频；计数法

Abstract

Based on STC89C51RC SCM, through low-frequency multiplier technology will move to high frequency, and then counting method for measuring frequency, and a measurement range of 0.01HZ ~ 1MHZ, accuracy of 1 / 100 of measuring frequency. The frequency of only a few external resistance of containers and work the clock for the microcontroller crystal oscillator circuit, we can achieve frequency measurements, the hardware is simple, small size, easy to implement characteristics. Can directly drive LCD display frequency. The whole circuit by 5 V DC power supply, low power consumption, facilitate the production of portable measurement equipment.
 
Keywords：Frequency Measurement； STC89C51RC； octave； counting method

目 录
摘要………………………………………………………………………………………………………I
Abstract ……………………………………………………………………………………………….. II
1 前言………………………………………………………………………………………….. ...….…1
2 频率计的基本原理……………………………………………………………………………....…3
3 频率测量方法和倍频法测量误差………………………………………………………….…...4
 3.1  频率测量方法…………………………………………………………………………….…...4
 3.2  倍频法测量误差……………………………………………………………………………....5
4 总体方案设计……………………………………………………………………………………… 7
 4.1 硬件结构……………………………………………………………………………………......7
 4.2 各硬件介绍…………………………………………………………………………………......8
 4.2.1  信号处理模块………………………………………………………………….... ..…. 8
 4.2.2  锁相环FH865………………………………………………………………... .…..…..9
 4.2.3  128倍频电路的实现……………………………………………………………..... ..10
 4.2.4  4双向模拟开关CD4016…………………………………………….. ………....….. 11
 4.2.5 倍频电路的实现…………………………………………………………….…….….. 12
 4.2.6  STC89C51RC单片机………………………………………………………….... …..12
 4.2.7  按键控制…………………………………………………………………………….. 15
 4.2.8  显示模块………………………………………………………………….……... …..15
5 软件流程……………………………………………………. ……………………………….. .…..18
 5.1  MAIN函数………………………………………………………………………………….…18
 5.2  待测信号预处理函数………………………………………………………………….……18
5.3  外部中断0处理函数…………………………………………………………….……….….19
 5.4  定时器0处理函数………………………………………………………………………….19
 5.5  显示处理函数………………………………………………………………………….……19
 5.6  按键处理函数…………………………………………………………………………….…20
6 仿真调试………………………………………………………………………………….………...21
 6.1 仿真系统简介………………………………………………………………………..…..……21
 6.2 调试仿真结果…………………………………………………………..……………….…….21
7 总结…………………………………………………………………………….…….…22
致谢…………………………………………………………………………………..…………….. .…23
参考文献…………………………………………………………………………………………...... ..24
附录 源程序………………………………………………………………………………………....25

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