基于FPGA和單片機的多功能等精度頻率計

電子機電論文編號:JD126  字數:9504,頁數:38

目    錄
1  緒論........................................................................ 1
1.1研究背景及目的...............................................................1
1.2 頻率計相關研究狀況 .........................................................2
1.3 等精度數字頻率計實現方法和器件選擇 .........................................2
1.3.1  設計方法...............................................................  2
1.3.2  器件選擇...............................................................  4

2  系統總體設計 ............................................................... 5
2.1 系統組成....................................................................5
2.2 等精度測頻法誤差分析 ...................................................... 6
2.3 基本性能指標............................................................... 7

3  硬件部分電路設計與實現 ......................................................8
3.1 CPLD/FPGA測量模塊整體設計 ..................................................8
3.2 電路單元分模塊設計..........................................................9
3.2.1  頻率/周期測量模塊 ...................................................... 9
3.2.2  脈沖寬度和占空比測量模塊.................................................10
3.2.3  電源模塊...............................................................  11
3.2.4  輸入信號放大整形模塊.....................................................12

4  軟件部分設計...............................................................  13
4.1 單片機主體控制模塊..........................................................13
4.2 各子模塊流程圖及匯編源程序..................................................18
4.2.1  測頻子模塊 ..............................................................18

4.2.2  顯示子模塊 ..............................................................21
4.2.3  鍵盤掃描子模塊...........................................................23
4.2.4  其他相關子模塊 ..........................................................28

結論........................................................................... 30
致謝 ...........................................................................31
參考文獻 .......................................................................32
附錄1...........................................................................33
附錄2 ..........................................................................34

摘   要
  
本文主要論述了利用FPGA進行測頻計數，單片機實施控制實現多功能頻率計的設計過程。該頻率計利用等精度的設計方法，克服了基于傳統測頻原理的頻率計的測量精度隨被測信號頻率的下降而降低的缺點。等精度的測量方法不但具有較高的測量精度，而且在整個測頻區域內保持恒定的測試精度。該頻率計利用FPGA來實現頻率、周期、脈寬和占空比的測量計數。利用單片機完成整個測量電路的測試控制、數據處理和顯示輸出。
本文詳細論述了硬件電路的組成和單片機的軟件控制流程。其中硬件電路包括鍵輸入模塊、顯示模塊、輸入信號整形模塊以及單片機和FPGA主控模塊。設計器件采用Atmel公司的單片機AT89C51和Altera公司的EPF10K20TC144-3。鍵輸入模塊設置5個功能鍵；顯示模塊用8只74LS164完成LED的串行顯示；被測信號經限幅后由兩級直接耦合放大器進行放大，再經施密特觸發器整形后輸入FPGA；標準頻率采用50MHz。

關鍵詞：頻率計；測頻；等精度；單片機；FPGA

  Abstract
The reach paper mainly discussed the design process of multi-function cymometer that uses FPGA to count the frequency measurement and cymometer is also controlled by single chip computer. The cymometer 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 cymometer uses FPGA to realize the measuring count of frequency、period、pulse width and occupy-empty ratio. Single chip computer completes the rest 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 input module、display module、plastic module of input signal、single chip computer control module and FPGA main control module.
The cymometer adopts single chip computer AT89C51 of Atmel company and EPF10K20TC144-3 of Altera company. Key input module has 5 function key. Display module uses eight 74LS164 to realize the serial display of LED. First, the measuring signal amplitude is limited. Second, the signal is amplified by two class direct coupling amplifier. Finally, the signal inputs FPGA after it is trimmed by Smitter trigger. Standard frequency is 50MHz.

Key words:  Cymometer; Frequency measurement; Equal-precision; Single chip computer; FPGA