等精度数字频率计的设计

等精度数字频率计的设计

李艳秋

摘 要

基于传统测频原理的频率计的测量精度将随着被测信号频率的下降而降低，在实用中有很大的局限性，而等精度频率计不但有较高的测量精度，而且在整个测频区域内保持恒定的测试精度。运用等精度测量原理，结合单片机技术设计了一种数字频率计，由于采用了屏蔽驱动电路及数字均值滤波等技术措施，因而能在较宽定的频率范围和幅度范围内对频率，周期，脉宽，占空比等参数进行测量，并可通过调整闸门时间预置测量精度。选取的这种综合测量法作为数字频率计的测量算法，提出了基于FPGA 的数字频率计的设计方案。给出了该设计方案的实际测量效果，证明该设计方案切实可行，能达到较高的频率测量精度。

关键词 等精度测量，单片机，频率计，闸门时间，FPGA

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ABSTRACT

Along with is measured based on the traditional frequency measurement principle frequency meter measuring accuracy the signalling frequency the drop but to reduce, in is practical has the very big limitation, but and so on the precision frequency meter not only has teaches the high measuring accuracy, moreover maintains the constant test precision in the entire frequency measurement region. Using and so on the precision survey principle, unified the monolithic integrated circuit technical design one kind of numeral frequency meter, because has used the shield actuation electric circuit and technical measure and so on digital average value filter, thus could in compared in the frequency range and the scope scope which the width decided to the frequency, the cycle, the pulse width, occupied parameter and so on spatial ratio carries on the survey, and might through the adjustment strobe time initialization measuring accuracy. Selection this kind of synthesis measured the mensuration took the digital frequency meter the survey algorithm, proposed based on the FPGA digital frequency meter design proposal. Has produced this design proposal actual survey effect, proved this design proposal is practical and feasible, can achieve the high frequency measurement precision

Keywords Precision survey, microcontroller, frequency meter, strobe time，field

programmable gate array

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目 录

目 录

摘 要 ······························································································· I ABSTRACT ·························································································· III

1 绪论 ···························································································· 1 2 系统设计方案 ················································································ 2

2.1系统设计方案的选择 ····································································· 2

2.1.1 频率测量模块 ········································································ 2 2.1.2 周期测量模块 ········································································ 4 2.1.3 脉宽测量模块 ········································································ 4 2.1.4 占空比测量模块 ····································································· 4

3 系统总体设计方案 ·········································································· 5 4 CPLD/FPGA测频专用模块的VHDL程序设计 ··········································· 6

4.1 测频模块逻辑结构 ······································································· 6 4.2 各模块功能和工作步骤如下： ·························································· 6

4.2.1 测频/测周期的实现 ································································· 7 4.2.2 控制部件设计 ········································································ 7 4.2.3 脉冲宽度测量和占空比测量模块设计 ············································· 7 4.2.4 电路显示模块 ········································································ 8 4.2.5 数码管的编码表 ··································································· 10

5 单片机控制与运算程序的设计 ·························································· 11 5.1 AT89C51RC单片机简介 ································································· 11 5.2 软件调试系统 ··········································································· 19 5.3具体试验过程 ············································································ 20

5.3.1 第一次测试 ········································································ 20 5.3.2 第二次计算 ········································································ 22 5.4 系统调试的方法 ········································································· 23 5.4.1 调试的软/硬件 ···································································· 23 5.4.2 系统的仿真结果 ··································································· 23 5.5 设计技巧分析 ··········································································· 25 5.6 系统扩展思路 ··········································································· 25

6 VHDL程序语言和FPGA简介 ······························································ 26 6.1 vhdl程序语言介绍: ···································································· 26 6.2 FPGA 简介 ··············································································· 28 6.3 VHDL 在FPGA中的运用 ································································· 29

攀枝花学院本科毕业设计（论文） 目录

结论 ································································································· 32 附录A：单片机程序和VHDL程序 ···························································· 33 参考文献 ··························································································· 56 致 谢 ······························································································· 57

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