基于CPLD和单片机的频率测量计的设计毕业论文.doc

中文题目：基于CPLD和单片机的频率测量计的设计 外文题目：THE DESIGN OF FREQUENCY MEASUREMENT BASED ON CPLD AND SINGLE CHIP MICYOCO 毕业设计（论文）共 70 页 图纸共2张 完成日期 20011年6月 答辩日期 20011年6月 摘要 本文主要论述了利用CPLD进行测频计数，单片机实施控制实现等精度频率计的设计过程。该频率计利用等精度的设计方法，克服了基于传统测频原理的频率计的测量精度随被测信号频率的下降而降低的缺点。等精度的测量方法不但具有较高的测量精度，而且在整个频率区域保持恒定的测试精度。该频率计利用CPLD来实现频率的测量计数。利用单片机完成整个测量电路的测试控制、数据处理和显示输出。 本文详细论述了硬件电路的组成和单片机的软件控制流程。其中硬件电路包括键控制模块、显示模块、输入信号整形模块以及单片机和CPLD主控模块。设计器件采用Atmel公司的单片机AT89C51和Altera公司的FPGA芯片MAX7000系列EPM7128SLC84-15。键控制模块设置1个开始键和3个时间选择键，键值的读入采用一片74LS165来完成；显示模块用8只74LS164完成LED的串行显示；被测信号经限幅后由两级直接耦合放大器进行放大，再经施密特触发器整形后输入CPLD；标准频率采用40MHZ有源晶振动实现；单片机软件用汇编语言编写，软件模块对应于硬件电路的每一个部分，还包括部分数据计算和转换模块。 关键词：单片机；CPLD；频率计；测频；等精度 Abstract The reach pape rmainly discusses the design process of equal-accuracy frequency meter that uses CPLD to count the frequency measurement and frequency meter is also controled by single chip computer. The frequency meter makes use of equal-accuracy design that can overcome the disadvantage of traditional measuring principle, which precision declines as measured signal frequency does. The equal-accuracy measurement not only has higher measuring precision, but also can keep invariable measuring precision in whole area of frequency. This frequency meter uses CPLD to realize the measuring count of frequency. Single chip computer completes the test control、data processing and display output of the system. This essay discusses the compose of hardware circuit and software control flow of single chip computer in detail. Hardware circuit includes key control module、display module, plastic module of input signal、single chip computer control module and CPLD main control module. The frequency meter adopts single chip computer AT89C51 of Atmel company and EPM7128SLC84-15 of Altera company. Key control module has 1 function key and 3 time selection key. A chip 74LS165 completes the key value input. Display module uses eight 74LS165s to realize the serial