單片機薄膜諧振式水位傳感器的高度測量用頻率計設(shè)計
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摘 要
本文介紹了一種以單片機(AT89C51)為核心與薄膜諧振式水位傳感器配套使用的液位高度測量用頻率計的設(shè)計與制作。還介紹了諧振式水位傳感器的新型傳感原理,傳感器的結(jié)構(gòu),數(shù)字振蕩電路的特點，闡述了水位與頻率的對應(yīng)關(guān)系。薄膜諧振式水位傳感器內(nèi)置三點式水位傳感器振蕩電路，該振蕩電路的固有頻率隨水位的變化而變化，通過檢測該振蕩電路的固有頻率來判定水位的高低。
該頻率計直接利用單片機內(nèi)部的計數(shù)器對薄膜諧振式水位傳感器的頻率脈沖信號進行計數(shù)，然后利用單片機的定時功能實現(xiàn)對頻率的檢測，最后通過LED動態(tài)顯示電路顯示數(shù)值。在設(shè)計中應(yīng)用了單片機的運算和控制功能，滿足測量的精度要求，該頻率測量儀器測量誤差小于±10Hz測頻性能穩(wěn)定可靠，可單獨使用，也可方便嵌入系統(tǒng)中。
該頻率計具有結(jié)構(gòu)簡單、價格低、精度高、操作簡單、并且降低產(chǎn)品的成本,有利于新產(chǎn)品的設(shè)計與研制、等特點。隨著單片機應(yīng)用技術(shù)的發(fā)展，越來越多的測量儀器都采用單片機作為系統(tǒng)進行設(shè)計，應(yīng)用單片機進行系統(tǒng)設(shè)計時系統(tǒng)結(jié)構(gòu)簡單、控制方便、硬件設(shè)計需要外圍器件較少，軟件設(shè)計可采用匯編語言編程，匯編語言具有編程方便、運算效率高、占用內(nèi)存少等優(yōu)點。

關(guān)鍵詞： 液位檢測；頻率測量；傳感器；單片機




Abstract
This paper presents the design and fabrication of a Microprocessor (AT89C51)based film resonant with the water level sensor supporting the use of the liquid level measurement frequencymeter.The principle of new resonator water level sensor is mainly introduced.The internal structure of this Sensor and the characteristic of numeral oscillation circuit are analyze dindetails.There ationship between frequently and water level is expounded.Films resonant water level sensor built-in three-point level sensor oscillation circuit.The oscillator circuit changed with the natural frequency of the water level. By detecting the oscillation circuit natural frequency to determine the level of water.
The frequencymeter use the Microprocessor internal counter to counting the film resonant frequency of the water level sensor pulse,then Microprocessor regular function to achieve frequency testing, final adoption of LED display circuit dynamic numerical show.Application of the design of the 89C51 operation and control functions，Meet the required precision measurement，The error of the frequency measurement instrument is less than ±10Hz，Performance measurement frequency stability and reliability,Also it can be used alone, and easily embedded in the system.
The frequency- meter also has a simple structure, low cost, high accuracy and simple operation,reduce the cost of the product and facilitate the design and development of new product and so on. With the development of the Microprocessor technology, a growing number of measuring instruments are used as a single chip computer system design. Microprocessor system design is simple, easy to control, hardware design requires fewer external components, Software Design use assembly language programming, because assembly language with high computational efficiency and low memory consume.

Keywords: Water Level Measurement； Frequency Measurement； Sensors；Microprocessor


目 錄
1 緒論...............................................................1
1.1選題的目的及意義 1
1.2 頻率測量儀器的現(xiàn)狀及發(fā)展 1
1.3 頻率計的設(shè)計內(nèi)容及要求 2
2 薄膜諧振式水位傳感器應(yīng)用...........................................3
2.1 薄膜諧振式水位傳感器概述 3
2.1.1 薄膜諧振式水位傳感器的結(jié)構(gòu) 3
2.1.2水位傳感器的工作原理 3
2.2薄膜諧振式水位傳感器的功能簡介 4
2.2.1水位檢測 4
2.2.2水位與頻率關(guān)系的對應(yīng) 4
3 頻率計總體方案設(shè)計.................................................6
3.1方案論證與比較 6
3.1.1 方案一 6
3.1.2 方案二 7
3.2 方案選擇 7
4 頻率計硬件分析與設(shè)計...............................................8
4.1頻率計系統(tǒng)的組成與基本工作原理 8
4.1.1 系統(tǒng)組成 8
4.1.2 系統(tǒng)設(shè)計原理 8
4.1.3 測頻原理 9
4.2 AT89C51單片機在本系統(tǒng)中的應(yīng)用 9
4.2.1 AT89C51簡介 9
4.2.2 AT89C51器件的基本結(jié)構(gòu) 11
4.2.3 AT89C51的定時器/計數(shù)器 13
4.2.4 AT89C51外圍電路設(shè)計 14
4.3 地址鎖存器74LS373介紹 14
4.4 八路反相緩沖器74LS240應(yīng)用 15
4.5 顯示電路 16
4.5.1顯示電路設(shè)計 16
4.5.2單片機驅(qū)動數(shù)碼管原理 17
4.6 硬件總電路圖 17
5 軟件設(shè)計.........................................................18
5.1主程序設(shè)計 18
5.2 中斷服務(wù)子程序設(shè)計 19
5.3 顯示子程序設(shè)計 20
6 運行與調(diào)試........................................................21
6.1硬件調(diào)試 21
6.2 軟件程序調(diào)試 22
6.2.1 MedWin仿真軟件簡介 22
6.2.2 匯編語言程序的仿真調(diào)試 22
6.3系統(tǒng)聯(lián)調(diào) 23
7 結(jié)論與展望........................................................25
7.1 結(jié)論 25
7.2 展望 25
謝辭................................................................26
參考文獻............................................................27
附錄 1..............................................................28
程序清單 28
附錄 2..............................................................33
硬件總電路圖 33



參考文獻
[7] 何立民.單片機原理及應(yīng)用系統(tǒng)設(shè)計.北京:北京航空航天大學(xué)出版社
[8] 曹玲芝、孫玉勝．水位傳感器專用頻率計的設(shè)計．鄭州輕工業(yè)學(xué)院學(xué)報
[9] 扈剛、王延峰. 諧振式水位傳感器. 傳感器技術(shù)
[10]李朝青.單片機原理及接口技術(shù).北京:北京航空航天學(xué)院出版社


附錄1
程序清單
================主程序 ====================
ORG 0000H ;復(fù)位地址
LJMP MAIN ;轉(zhuǎn)主程序
ORG 000BH ;T0中斷入口地址
LJMP ZDZD ;轉(zhuǎn)T0中斷服務(wù)程序
......


附錄2
硬件總電路圖