【導(dǎo)讀】單片機(jī)建議選用STC12C520XAD系列SKDIP28封裝。字符液晶選用LCD1602A。如果需要用到運(yùn)放，可以選用LM358或324。顯示要求：保留1位小數(shù)點(diǎn)，單位用N。關(guān)的外文資料不少于3000漢字。被測電容范圍較大，選用振蕩電路時(shí)，要考慮這個(gè)因素。用外部中斷測量震蕩頻率，然后計(jì)算電容值。必要時(shí)可用施密特觸發(fā)器對信號整形。因此掌握好精密型數(shù)字電容表制作的一般設(shè)計(jì)方法，對于工。路等幾個(gè)階段的發(fā)展，到位處理器的出現(xiàn)，使數(shù)字電容表的性能產(chǎn)生了質(zhì)的飛躍。本文設(shè)計(jì)的基于單片機(jī)的數(shù)字電容表，其主要構(gòu)成采用的是單片機(jī)和字符液晶LCD1602A。更可靠的特點(diǎn)和易于調(diào)試的優(yōu)點(diǎn)，可以提高電容表工作的可靠性和性能指標(biāo)。系統(tǒng)故障診斷提供了便捷的工具。內(nèi)部含有自校零雙積分電容表所需的全部模擬和數(shù)字電路。阻電容和LED數(shù)碼管就可組成一只精確而穩(wěn)定的數(shù)字電容表。顯示方面采用字符液晶LCD1602A的動(dòng)態(tài)顯示，需要CPU時(shí)刻對顯示器件進(jìn)行數(shù)據(jù)刷新，具有很好的實(shí)用性。

　　

【正文】 下數(shù)據(jù)表格 表 41 電容測量值與實(shí)際值的比較 被測電容值 測量值 通過表中的數(shù)據(jù)可以看出仿真的數(shù)據(jù)還是比較準(zhǔn)確的，但是在實(shí)際的操作中，測量值可能沒有這么準(zhǔn)確，因?yàn)樵趯?shí)際的電路中， 555 芯片輸出的方波可能不會(huì)如仿真時(shí)的那么標(biāo)準(zhǔn)平滑，波形不會(huì)那么理想，再 加上單片機(jī)的測量也會(huì)存在一些誤差，所以綜合以上的一些考慮，真實(shí)中的測量結(jié)果肯定要比仿真中的結(jié)果誤差大。 所以本次的方案算然說不能過非常精確的測出結(jié)果來，但是相比較一些能夠測出比較精確結(jié)果的電路來，本電路是實(shí)現(xiàn)起來很容易，測量結(jié)果也比較準(zhǔn)確，實(shí)際操作中比較有保障的一種電路。 石家莊鐵道大學(xué)四方學(xué)院畢業(yè)設(shè)計(jì) 19 第 5 章 結(jié) 論 畢業(yè)論文是一次非常好的將理論與實(shí)際相結(jié)合的機(jī)會(huì)，通過對電容測試儀的課題設(shè)計(jì)，鍛煉了我的實(shí)際動(dòng)手能力，增強(qiáng)了我解決實(shí)際工程問題的能力，同時(shí)也提高我查閱文獻(xiàn)資料、設(shè)計(jì)規(guī)范以及電腦制圖等其他專業(yè)能力 水平。 本設(shè)計(jì)的硬件電路比較簡單，這大大的降低了成本。而采用單片機(jī)可以提高系統(tǒng)的可靠性和穩(wěn)定性， 縮小系統(tǒng)的體積 ,調(diào)試和維護(hù)方便。本設(shè)計(jì)通過由 555 芯片和電容電阻組成的振蕩電路來輸出方波，通過單片機(jī)定時(shí)器 T0 測量其脈沖寬度，從而達(dá)到測量其周期的目的，再通過單片機(jī)軟件編程，對數(shù)據(jù)進(jìn)行進(jìn)一步的計(jì)算從而得出被測電容的值，再通過 LCD1602 顯示出其測量值。 系統(tǒng)的軟件部分是系統(tǒng)實(shí)現(xiàn)功能的關(guān)鍵，軟件部分是 在 Keil51 的平臺(tái)上 使用是 C語言編寫程序。本系統(tǒng)通過一個(gè)測量按鍵啟動(dòng)整個(gè)測量程序，通過外部中斷零 INT0來控制計(jì) 數(shù)器 T0 的開始和停止， INT0 采用邊沿觸發(fā)方式，在第一個(gè)脈沖邊沿啟動(dòng)T0，使 T0 開始計(jì)數(shù)，在第二個(gè)脈沖邊沿停止 T0 計(jì)數(shù)，然后通過對數(shù)據(jù)的計(jì)算和處理最后將數(shù)據(jù)顯示在 LCD1602 上。 總之，整個(gè)系統(tǒng)的工作正常，完成了設(shè)計(jì)任務(wù)的全部要求 雖然本設(shè)計(jì)完成了設(shè)計(jì)任務(wù)，但無法得到十分精確的測量結(jié)果，這主要是有以下幾點(diǎn)原因，首先單片機(jī)對于脈沖寬度的測量精確度有限，其次是外界的干擾對波形有一定的影響，還有硬件自身也有一部分原因。 希望在之后的設(shè)計(jì)之中能夠得到進(jìn)一步解決。 石家莊鐵道大學(xué)四方學(xué)院畢業(yè)設(shè)計(jì) 20 參考文獻(xiàn) [1] 楊素行 . 模擬電子技術(shù)基礎(chǔ) 簡明教程 (第三版 ).高等教育出版社 . [2] 李群芳，肖看 . 單片機(jī)原理接口及應(yīng)用技術(shù) [M]. 北京：清華大學(xué)出版社， 2020： 36～ 47. [3] 周堅(jiān) . 單片機(jī)輕松入門 [M]. 第二版 . 北京：北京航空航天大學(xué)出版社， 2020： 60～ 80. [4] 高峰 . 單片微型計(jì)算機(jī)原理與接口技術(shù) [M]. 第二版 . 北京：科學(xué)出版社， 2020： 15～ 20. [5] 趙廣林 . 常用電子元器件識別 /檢測 /選用一讀通 .北京 [M]. 電子工業(yè)出版社 3241. [6] 劉衛(wèi)國 . C 語言程序設(shè)計(jì) [M]. 北京：鐵道大學(xué)出版 社， 2020： 30～ 41. [7] 徐愛鈞 , 彭秀華 . KeilCx51 單片機(jī)高級語言編程與 uVision2 應(yīng)用實(shí)踐 [M] .電子工業(yè)出版社 2020 年 3142. [8] 夏繼強(qiáng) . 單片機(jī)實(shí)驗(yàn)與實(shí)踐教程 . 北京：北京航空航天大學(xué)出版社 , 2020. [9] 謝自美 . 電子線路設(shè)計(jì)實(shí)驗(yàn)測試 (第二版 ).武漢 :華中理工大學(xué)出版社， 2020. [10] Stephan innovations demanded by PCB tools:Industial Diamond Review[J],2020(3):32. [11] des Relations Intermationals[M] :Dalloz,1988. [12] 康華光 . 《電子技術(shù)基礎(chǔ)》（模擬部分 第五版） [M]. 高等教育出版社 , 2020. [13] 戴衛(wèi)恒 . 51 單片機(jī) C 語言應(yīng)用程序設(shè)計(jì)實(shí)例精講 [M]. 北京：電子工業(yè)出版， 石家莊鐵道大學(xué)四方學(xué)院畢業(yè)設(shè)計(jì) 21 致 謝 此次設(shè)計(jì)實(shí)踐是本科四年來對自己所學(xué)知識的一個(gè)總結(jié)，其難度、復(fù)雜性 、對設(shè)計(jì)的要求都是以前所不能比擬的。所要用到的知識及相關(guān)的資料有相當(dāng)部分超出我們四年的所學(xué)，需要我們自己通過其他途徑獲取信息，自己在重新學(xué)習(xí)增長自己的知識和認(rèn)識。 在此特別感謝楊老師，在此次設(shè)計(jì)中給予我很多幫助，是自己深刻認(rèn)識到了雖然自己要畢業(yè)了，可是自己要學(xué)習(xí)的東西還有很多很多，并對我要求嚴(yán)格，在各方面對我進(jìn)行細(xì)心指導(dǎo)，讓自己為馬上要參加工作打下了良好的基礎(chǔ)，在此表示誠摯的致意和衷心的感謝。 在這四年中，還要感謝全體老師，是他們在教學(xué)上的認(rèn)真負(fù)責(zé)，為廣大學(xué)生創(chuàng)造了良好的學(xué)習(xí)環(huán)境。 還要特別感謝我的同學(xué)，正 是與他們在許多問題上的交流、討論，在他們的幫助之下，我的論文才得以順利完成。 最后向所有關(guān)心和幫助過我的人表示真心的感謝 ! 石家莊鐵道大學(xué)四方學(xué)院畢業(yè)設(shè)計(jì) 22 附 錄 附錄 A 外文資料 Singlechip SCM is also known as microcontroller (Microcontroller Unit), monly used letters of the acronym MCU that it was first used in industrial control. Only a single chip by the CPU chip developed from a dedicated processor. The first design is by a large number of peripherals and CPU on a chip in the puter system, smaller, more easily integrated into a plex and demanding on the volume control device which. INTEL39。sZ80 is the first designed in accordance with this idea processor, then on the development of microcontroller and dedicated processors have parted ways. Single chip, also known as singlechip microcontroller, it is not plete a certain logic chips, but to a puter system integrated into a to a microputer, and puter than just the lack of a microcontroller I / O devices. General talk: a chip bees a puter. Its small size, light weight, cheap, for the study, application and development of facilities provided. At the same time, learning to use the MCU is to understand the principle and structure of the puter the best choice. SCM and the puter functions internally with similar modules, such as CPU, memory, parallel bus, the same effect as well, and hard disk memory devices, and different is its performance of these ponents were relatively weak many of our home puter, but the price is low , usually not more than 10 yuan you can do with it ...... some control for a class is not very plicated electrical work is enough of. We are using automatic drum washing machine, smoke hood, VCD and so on appliances which could see its shadow! It is primarily as a control section of the core ponents It is an online realtime control puter, controlline is that the scene is needed is a stronger antijamming ability, low cost, and this is, and offline puter (such as home PC), the main difference. Single chip MCU is through running, and can be modified. Through different procedures to achieve different functions, in particular special unique features, this is another device 石家莊鐵道大學(xué)四方學(xué)院畢業(yè)設(shè)計(jì) 23 much effort needs to be done, some great efforts are very difficult to do. A not very plex functions if the 5039。s with the United States developed 74 series, or the 6039。s CD4000 series of these pure hardware buttoned, then the circuit must be a large PCB board! But if the United States if the 7039。s with a series of successful SCM market, the result will be a drastic change! Just because you are prepared by microputer programs can achieve high intelligence, high efficiency and high reliability! As the microcontroller on the costsensitive, so now the dominant software or the lowest level assembly language, which is the lowest level in addition to more than binary machine code language, and as so low why is the use? Many highlevel language has reached the level of visual programming Why is not it? The reason is simply that there is no home puter as a single chip CPU, not as hard as a mass storage visualization of small highlevel language program which even if only one button, will reach tens of K of size! For the home PC39。s hard drive in terms of nothing, but in terms of the MCU is not acceptable. SCM in the utilization of hardware resources to be very high for the job so although the original is still in the pilation of a lot of use. The same token, if the giant puter operating system and applications run up to get home PC, home PC, also can not afford to. Can be said that the twentieth century across the three power era, that is, the age of electricity, the electronic age and has entered into the puter age. However, this puter, usually refers to the personal puter, referred to as PC. It consists of the host, keyboard, monitor and other ponents. Another type of puter, most people do not know how. This puter is to give all kinds of intelligent machines single chip (also known as microcontroller). As the name suggests, this puter system took only a minimal integrated circuit, can be a simple operation and control. Because it is small, usually hidden in the charged mechanical stomach in. It is in the device, like the human brain plays a role, it goes wrong, the whole plant was paralyzed. Now, this microcontroller has a very broad field of use, such as smart meters, realtime industrial control, munications equipment, navigation systems, and household appliances. Once all kinds of products were using SCM, can serve to upgrade the effectiveness of products, often in the product name preceded by the adjective intelligent, such as intelligent washing machines. Now some technical personnel of factories or other amateur electronics developers to engage in out of certain products, not the circuit is too plicated, that function is too simple and can easily be copied. The reason may be stuck in the product did 石家莊鐵道大學(xué)四方學(xué)院畢業(yè)設(shè)計(jì) 24 not use a microcontroller or other programmable logic device. SCM history SCM was born in the late 20th century, 70, experienced SCM, MCU, SOC three stages. First model the single chip microputer (Single Chip Microputer) stage, mainly seeking the best of the best