摘  要
在電子領(lǐng)域內(nèi),頻率是一種最基本的參數(shù),并與其他許多電參量的測(cè)量方案和測(cè)量結(jié)果都有著十分密切的關(guān)系。由于頻率信號(hào)抗干擾能力強(qiáng)、易于傳輸，可以獲得較高的測(cè)量精度。因此,頻率的測(cè)量就顯得尤為重要，測(cè)頻方法的研究越來(lái)越受到重視。
頻率計(jì)作為測(cè)量?jī)x器的一種，常稱為電子計(jì)數(shù)器，它的基本功能是測(cè)量信號(hào)的頻率和周期頻率計(jì)的應(yīng)用范圍很廣,它不僅應(yīng)用于一般的簡(jiǎn)單儀器測(cè)量,而且還廣泛應(yīng)用于教學(xué)、科研、高精度儀器測(cè)量、工業(yè)控制等其它領(lǐng)域。隨著微電子技術(shù)和計(jì)算機(jī)技術(shù)的迅速發(fā)展，特別是單片機(jī)的出現(xiàn)和發(fā)展，使傳統(tǒng)的電子側(cè)量?jī)x器在原理、功能、精度及自動(dòng)化水平等方面都發(fā)生了巨大的變化，形成一種完全突破傳統(tǒng)概念的新一代側(cè)量?jī)x器。頻率計(jì)廣泛采用了高速集成電路和大規(guī)模集成電路，使儀器在小型化、耗電、可靠性等方面都發(fā)生了重大的變化。目前,市場(chǎng)上有各種多功能、高精度、高頻率的數(shù)字頻率計(jì),但價(jià)格不菲。
為適應(yīng)實(shí)際工作的需要,本次設(shè)計(jì)給出了一種較小規(guī)模和單片機(jī)(AT89S52)相結(jié)合的頻率計(jì)的設(shè)計(jì)方案,不但切實(shí)可行,而且體積小、保密性強(qiáng)、設(shè)計(jì)簡(jiǎn)單、成本低、精度高、可測(cè)頻帶寬，大大降低了設(shè)計(jì)成本和實(shí)現(xiàn)復(fù)雜度。頻率計(jì)的硬件電路是用Protel繪圖軟件繪制而成，軟件部分的單片機(jī)控制程序，是以KeilC做為開(kāi)發(fā)工具用C語(yǔ)言編寫而成，而頻率計(jì)的實(shí)現(xiàn)則是選用Ptotues仿真軟件來(lái)進(jìn)行模擬和測(cè)試。

關(guān)鍵詞：?jiǎn)纹瑱C(jī)；AT89S52；頻率計(jì)；C語(yǔ)言
 
ABSTRACT
In the electronic field, frequency is a kind of most basic parameter, and all there are close relations in the measurement schemes of many other electric parameters and result of measuring. Because the signal anti-interference ability of frequency is strong, easy to transmit, can obtain higher measurement precision. So, the measurement of frequency seems particularly important, the research of the method is being paid attention to.
The Frequency meter, as one kind of the measuring instrument, often called the electronic counter, its basic function is that frequency and application of cycle Frequency meter of measuring the signal are in a very large range, it not only applies to general simple instrument measurement but also apply to other fields such as teaching, scientific research, high-accuracy instrument measuring, industrial control extensively. With the rapid development of microelectric technique and computer technology, especially appearance and development of the one-chip computer, the instruments have all changed enormously in such aspects as principle, function, precision and automatic level to enable the traditional electronic side amount, form a kind of side amount instrument of new generation that totally broke through the traditional concept. The Frequency meter has adopted the high-speed integrated circuit and large scale integrated circuit extensively, make the instrument change greatly in such aspects as miniaturize, power consumptive, dependability. At present, there are various digital Frequency meter of multi-function, high precision, high frequency on the market, but the price is high.
In order to meet the need of the real work, design and provide one this time The design plan of Frequency meter combining with one-chip computer (AT89S52) on a small scale, not only feasible, and small, of good security, design simply, with low costs, the precision is high, can examine the bandwidth frequently, have reduced the design cost and realized complexity greatly. The hardware circuit of the Frequency meter is drawing with Protel mapping software, the one-chip computer control procedure of the software part, regarded KeilC as the developing instrument to write in C language, but the realization of the Frequency meter was to select to carry on imitating and test with Protues artificial software.

Key Words：single chip computer; AT89S52; frequency meter; C language 
目  錄
1 緒 論 1
1.1 課題的引入 1
1.2 產(chǎn)生背景 1
1.3 國(guó)內(nèi)外研究現(xiàn)狀 2
1.4 單片機(jī)頻率計(jì)設(shè)計(jì)的目的及意義 2
2 AT89S52單片機(jī)介紹及其發(fā)展概況 4
2.1 單片機(jī)的介紹 4
2.1.1 單片機(jī)概述 4
2.1.2 單片機(jī)的發(fā)展 5
2.1.3 單片機(jī)的特點(diǎn)及應(yīng)用 5
2.2 AT89S52系列單片機(jī) 6
2.2.1 AT89系列單片機(jī) 6
2.2.2 AT89S52系列單片機(jī)的基本結(jié)構(gòu) 7
3 頻率計(jì)總體方案設(shè)計(jì) 10
3.1 頻率計(jì)設(shè)計(jì)原理 10
3.1.1 頻率檢測(cè)實(shí)現(xiàn)方法 10
3.1.2 頻率計(jì)測(cè)頻原理 11
3.2 設(shè)計(jì)思路及方法 11
3.2.1 頻率計(jì)方案概述 12
3.2.2 頻率計(jì)的量程自動(dòng)切換 12
4 系統(tǒng)的硬件設(shè)計(jì) 14
4.1 時(shí)鐘信號(hào)發(fā)生器 14
4.2 AT89S52 控制寄存器 15
4.2.1 AT89S52中斷控制系統(tǒng) 15
4.2.2 AT89S52定時(shí)/計(jì)數(shù)器的控制 17
4.3 LCD1602顯示電路 18
4.3.1 LCD1602的主要技術(shù)參數(shù)及接口說(shuō)明 19
4.3.2 控制器接口及時(shí)序 19
4.3.3 頻率計(jì)硬件電路整體設(shè)計(jì) 20
5 系統(tǒng)的軟件設(shè)計(jì) 22
5.1 Keil C簡(jiǎn)介 22
5.2 頻率計(jì)程序的建立過(guò)程 23
5.3 軟件功能模塊設(shè)計(jì) 27
5.3.1 LCD初始化設(shè)置模塊 28
5.3.2 浮點(diǎn)數(shù)到ASCII碼轉(zhuǎn)換模塊 28
5.3.3 定時(shí)/計(jì)數(shù)器初始化模塊 29
5.3.4 定時(shí)器中斷服務(wù)模塊子程序 29
6 系統(tǒng)的模擬及仿真 31
6.1 Proteus ISIS簡(jiǎn)介 31
6.1.1 Proteus ISIS的概況簡(jiǎn)介及特點(diǎn) 31
6.1.2 Proteus ISIS的運(yùn)行概況 31
6.1.3 用Proteus 軟件虛擬單片機(jī)實(shí)驗(yàn)的優(yōu)點(diǎn) 32
6.2 系統(tǒng)的模擬與仿真過(guò)程 33
6.3 頻率計(jì)系統(tǒng)仿真分析 37
結(jié)束語(yǔ) 41
致謝 42
參考文獻(xiàn) 43