【正文】 究竟是哪個數(shù)碼管亮，則取決于COM端。 DS18B20數(shù)字溫度傳感器采集現(xiàn)場溫度，經(jīng)過單片機(jī)處理后顯示當(dāng)前溫度值，并與設(shè)定溫度值的上下限值作比較，若高于設(shè)定上限值或低于設(shè)定下限值則控制風(fēng)速進(jìn)行調(diào)整。s才能完成復(fù)位操作。時鐘電路復(fù)位電路AT89C51I/0口圖33 單片機(jī)最小系統(tǒng)原理框圖1. 時鐘電路在AT89C51單片機(jī)內(nèi)部有一振蕩電路，只要在單片機(jī)的XTAL1(18)和XTAL2(19)引腳外接石英晶體(簡稱晶振)，就構(gòu)成了自激振蕩器并在單片機(jī)內(nèi)部產(chǎn)生時鐘脈沖信號。注意加密方式1時，EA將內(nèi)部鎖定為RESET；當(dāng)/EA端保持高電平時，此間內(nèi)部程序存儲器。如想禁止ALE的輸出可在SFR8EH地址上置0。P3口也可作為AT89C51的一些特殊功能口，如下表所示：口管腳 備選功能 RXD（串行輸入口） TXD（串行輸出口） /INT0（外部中斷0） /INT1（外部中斷1） T0（計時器0外部輸入） T1（計時器1外部輸入） /WR（外部數(shù)據(jù)存儲器寫選通） /RD（外部數(shù)據(jù)存儲器讀選通）P3口同時為閃爍編程和編程校驗接收一些控制信號。并因此作為輸入時，P2口的管腳被外部拉低，將輸出電流。P0口：P0口為一個8位漏級開路雙向I/O口，每腳可吸收8TTL門電流。系統(tǒng)的框圖結(jié)構(gòu)如下：通過修改程序可方便實(shí)現(xiàn)系統(tǒng)升級。對于方案二，PWM的一個優(yōu)點(diǎn)是從處理器到被控系統(tǒng)信號都是數(shù)字形式的，無需進(jìn)行數(shù)模轉(zhuǎn)換。但是液晶顯示模塊價格昂貴，驅(qū)動程序復(fù)雜，從簡單實(shí)用的原則考慮，本系統(tǒng)采用方案一。方案一：采用數(shù)碼管顯示溫度，動態(tài)掃描顯示方式。方案一：采用電壓比較電路作為控制部件。此方案原理和方案一的原理大同小異，AD轉(zhuǎn)換電路一樣，就是模擬量輸入的處理方式不一樣，熱電偶的還需要配合橋式電路，整體更加復(fù)雜點(diǎn)，但是此方案的測溫范圍更廣。它的廣泛應(yīng)用和普及將給人們的日常生活帶來極大的方便，其發(fā)展趨勢可根據(jù)其性質(zhì)進(jìn)行相應(yīng)的改進(jìn)可以運(yùn)用與不同場合的溫度監(jiān)測控制，并帶來大量的經(jīng)濟(jì)效益。本設(shè)計為一種溫控風(fēng)扇系統(tǒng)，具有靈敏的溫度檢測和顯示功能，采用單片機(jī)AT89C51為核心控制器對風(fēng)扇轉(zhuǎn)速進(jìn)行控制，使用溫度傳感器DS18B20檢測溫度數(shù)據(jù)，通過數(shù)碼管顯示實(shí)時溫度，根據(jù)采集的溫度，實(shí)現(xiàn)了風(fēng)扇的自起自停?？捎墒褂谜咴O(shè)置高、低溫度值，測得溫度值在高低溫度之間時打開風(fēng)扇弱風(fēng)檔，當(dāng)溫度升高超過所設(shè)定的溫度時自動切換到大風(fēng)檔，當(dāng)溫度小于所設(shè)定的溫度時自動關(guān)閉風(fēng)扇，控制狀態(tài)隨外界溫度而定。本設(shè)計以AT89C51單片機(jī)為核心，通過溫度傳感器對外界環(huán)境溫度進(jìn)行數(shù)據(jù)采集，從而建立一個控制系統(tǒng)，使電風(fēng)扇隨溫度的變化而自動調(diào)節(jié)檔位，實(shí)現(xiàn)“溫度高、風(fēng)力大、溫度低、風(fēng)力弱”的性能。方案三：采用數(shù)字式集成溫度傳感器DS18B20作為感測溫度的核心元件，直接輸出數(shù)字溫度信號供單片機(jī)處理。溫度傳感器采用熱敏電阻或熱電偶等，溫度信號轉(zhuǎn)為電信號并放大，由集成運(yùn)放組成的比較電路判決控制風(fēng)扇轉(zhuǎn)速，當(dāng)高于或低于某值時將風(fēng)扇切換到相應(yīng)檔位。采用LED數(shù)碼管這種方案。方案一：采用變壓器調(diào)節(jié)方式，運(yùn)用電磁感應(yīng)原理將220V電壓通過線圈降壓到不同的電壓，控制風(fēng)扇電機(jī)接到不同電壓值的線圈上可控制電機(jī)的轉(zhuǎn)速，從而控制風(fēng)扇風(fēng)力大小。讓信號保持為數(shù)字形式可將噪聲影響降到最小。系統(tǒng)的框圖結(jié)構(gòu)如下：數(shù)碼管驅(qū)動電路風(fēng)扇驅(qū)動電路風(fēng)扇復(fù)位電路溫度采集電路單片機(jī)晶振電路按鍵設(shè)置電路數(shù)碼管顯示圖31 系統(tǒng)框圖AT89C51是美國ATMEL公司生產(chǎn)的低電壓，高性能CMOS 8位單片機(jī)，片內(nèi)含4k bytes的可反復(fù)擦寫的只讀程序存儲器（PEROM）和128 bytes的隨機(jī)存儲數(shù)據(jù)存儲器（RAM）；器件采用ATMEL公司的高密度、非易失性存儲技術(shù)生產(chǎn)；兼容標(biāo)準(zhǔn)MSC51指令系統(tǒng)，片內(nèi)置通用8位中央處理器（CPU）和Flash存儲單元，功能強(qiáng)大AT89C51可靈活應(yīng)用于各種控制領(lǐng)域。當(dāng)P0口的管腳第一次寫1時，被定義為高阻輸入。這是由于內(nèi)部上拉的緣故。RST：復(fù)位輸入。此時， ALE只有在執(zhí)行MOVX，MOVC指令是ALE才起作用。在FLASH編程期間，此引腳也用于施加12V編程電源（VPP）。圖中電容C1和C2的作用是穩(wěn)定頻率和快速起振，電容選30pF，晶振頻率選擇12MHz。圖36 DS18B20溫度采電路本電路的顯示驅(qū)動模塊是由74HC573芯片來完成的，74HC573包含八路D 型透明鎖存器，每個鎖存器具有獨(dú)立的D 型輸入，以及適用于面向總線的應(yīng)用的三態(tài)輸出。COM端與單片機(jī)的I/O接口相連接，由單片機(jī)輸出位位選碼到I/O接口，控制何時哪一位數(shù)碼管被點(diǎn)亮。按鍵釋放后，單片機(jī)內(nèi)部的上拉電阻使I/O口仍然保持高電平。如主機(jī)控制DS18B20完成溫度轉(zhuǎn)換這一過程，根據(jù)DS18B20的通訊協(xié)議，須經(jīng)三個步驟：每一次讀寫之前都要對DS18B20進(jìn)行復(fù)位，復(fù)位成功后發(fā)送一條ROM指令，最后發(fā)送RAM指令，這樣才能對DS18B20進(jìn)行預(yù)定的操作。判斷設(shè)置鍵是否按下設(shè)置按鍵按下延時去抖判斷當(dāng)前設(shè)置模式設(shè)置上限設(shè)置下限退出設(shè)置判斷加、減鍵是否按下修改設(shè)置的閥值結(jié)束NYYN圖44按鍵程序流程圖第五章 系統(tǒng)調(diào)試系統(tǒng)調(diào)試中為驗證DS18B20是否能在系統(tǒng)板上工作，將手心靠攏或者捏住芯片，即可發(fā)現(xiàn)LED顯示的前兩位溫度也迅速升高，驗證了DS18B20能在系統(tǒng)板上工作?？偨Y(jié)本次畢業(yè)設(shè)計的課題為智能溫控風(fēng)扇，本次課題是專業(yè)知識與實(shí)際很好的一次結(jié)合，為了更好的完成這次畢業(yè)設(shè)計，我們查閱了大量的關(guān)于溫度控制類書籍、學(xué)術(shù)論文等相關(guān)資料。正是在老師耐心的指導(dǎo)和熱情的幫助下，我們才能順利地完成這次畢業(yè)設(shè)計的任務(wù)。//設(shè)置溫度sbit key2=P3^6。39。 for(ms。 //DQ復(fù)位 delay_18B20(8)。 for (i=8。 for (i=8。 }}/**************讀取ds18b20當(dāng)前溫度************/void ReadTemperature(){ uchar a=0。 //跳過讀序號列號的操作 WriteOneChar(0xBE)。 //第1位 P0=0x00。delay(1)。P0=table[d3]。//松手檢測 } while(flag==1) { d1=18。 if(shang=100)shang=100。 display()。 if(key3==0) { xia=1。//按鍵掃描函數(shù) display()。i++){dj=0。} } if(wen_dushang){dj=1。 while(1) { ReadTemperature()。t help but sing the folk songs, Nasun says. The vastness of Inner Mongolia and the lack of entertainment options for people living there, made their lives lonely. The nomadic people were very excited about our visits, Nasun recalls. We didn39。s cultural foray overseas, has been widely panned by its home audience. Retitled Empresses in the Palace, the American version has been shortened from its original 76 episodes at 45 minutes each, to six 90minute episodes. The quick pacing threw off many native viewers, who are accustomed to a more leisurely daytimesoapstyle narrative rhythm. (Chinese TV stations would run two or three episodes every day.) I did not finish the fulllength version and found the truncated one not difficult to follow. What39。m nothing if not that! In his text he expounds on the idea that one must give their life a purpose. And that is the true topic of this entry. These last four years have been so easy: teach for a grand total of six hours a week, and the rest of my time is mine. Since I39。 he wondered how in the world he came to belong there. Indeed his penning and publishing this essay caused his exmunication from high society and also caused him a lot of legal trouble. The legal trouble came as a result of the fact that he was speaking out against the government. I like to reference such texts from time to time as an example both of the fact that history does repeat itself and that this world is not so big that what applies to one society does not in any way touch another society. On a much smaller scale,Emerson39。s president, who is also a renowned tenor, tells China Daily. During a tour in 1985, he went to a village and met an elderly local man, who told him a story about his friendship with a solider from Shenyang, capital of Northeast China39。s Zhangye city during their journey to Kazakhstan, May 5, 2015. The caravan, consisting of more than 100 camels, three horsedrawn carriages and four support vehicles, started the trip from Jingyang county in Shaanxi on Sept 19, 2014. It will pass through Gansu province and Xinjiang Uygur autonomous region, and finally arrive in Almaty, formerly known as AlmaAta, the largest city in Kazakhstan, and Dungan in Zhambyl province. The trip will cover about 15,000 kilometers and take the caravan more than one year to plete. The caravan is expected to return to Jingyang in March 2016. Then they will e back, carrying specialty products from Kazakhstan A small art troupe founded six