基于AT89C52的频率计设计毕业论文定稿.doc

摘 要 频率计作为一件很普遍的的电子器件，在很多领域都能够用到，目前大部分频率计的测频范围都很窄，有时不能满足所要测的频率。因此，本文提出宽频带频率计的的设计方案，以单片机AT89C52为控制核心，实现测量多种波形的频率值。 采用在高频段直接测频法，在低频段测周期法的设计思路；硬件部分由放大电路、波形变换和整形电路、闸门时基控制电路、分频电路、单片机和数据显示电路组成；软件部分由信号频率测量模块、周期测量模块、定时器中断服务模块、数据显示模块等功能模块实现。应用单片机的控制功能和数学运算能力，实现计数功能和频率、周期的换算。设计的频率计测量范围能够达到2HZ～1MHZ，满足所要求的频率范围，测量精度较高，平均相对误差低。 关键词：AT89C52；宽频带；频率计 ABSTRACT As a very common electronic components，The frequency meter is used in many areas. At present, most of the frequency meter measuring frequency range is very narrow, and sometimes it cant satisfy the frequency of the measure. Therefore, this paper puts forward the frequency meter wide band to realize the value of measurement frequency wave. This design is going to make the AT89C52 single chip microcomputer as control core. The high frequency band in direct frequency measurement method, at low frequency measurement cycle method of design thinking is to adopted; Hardware consists of amplifying circuit, wave transform and plastic circuit, gate, and the control circuit, points frequency circuit, SCM and data display circuit composed; Software is realized by the signal frequency measurement modules, cycle measurement modules, timer interrupt service module, data showed module and function modules. Application of the single chip microcomputer control function and mathematical operation ability can realize the count function and frequency of the conversion, period. The frequency of the design plan measurement range can reach 2 HZ ~ 1 MHZ, meeting the required frequency range, high measurement precision, the average relative error low. Keywords: AT89C52; Broadband belt; Frequency meter 目 录 1 绪论 1 1.1 课题的引入 1 1.2 背景 1 1.3 目的及意义 1 2 频率计总体方案设计 2 2.1 总体设计方案 2 2.2 测量方法分析 4 2.2.1 直接测频法 4 2.2.2 间接测量法（测周期法） 4 2.2.3 直接与间接相结合的方法 5 3 系统硬件设计 6 3.1 信号预处理电路 6 3.1.1 放大电路 6 3.1.2 波形变换和整形电路 7 3.1.3 闸门时基电路 8 3.1.4 分频电路 9 3.2 最小系统 11 3.2.1 AT89C52 11 3.2.2 复位电路 13 3.2.3 晶振电路 14 3.3 显示电路 14 3.4 总电路图 17 4 系统软