【正文】 要寫 0 時(shí)序時(shí)，單總線要被拉低至少 60us，保證 DS18B20 能夠在 15us 到 45us 之間能夠正確地采樣 IO 總線上的“0”電平，當(dāng)要寫 1 時(shí)序時(shí)，單總線被拉低之后，在 15us 之內(nèi)就得釋放單總線。i++) { if((mand amp。 _nop_()。 _nop_()。 //右移 1 位 循環(huán) 8 次 } } 從 DS18B20 讀數(shù)據(jù) 當(dāng)從DS18B20讀數(shù)據(jù)時(shí)，主機(jī)產(chǎn)生讀時(shí)序。因此，為了讀出從讀時(shí)序開始算起15微秒的狀態(tài)主機(jī)必須停止把1/0引腳驅(qū)動(dòng)至低電平，在讀時(shí)序結(jié)束時(shí)，1/0引腳經(jīng)過外部的上拉電阻拉回至高電平。 unsigned char temp。i++) { temp=_cror_(temp,1)。 DQ=1。//接收 1 } else { temp=temp|0x00。以上三條同時(shí)滿足時(shí)， CPU 才有可能響應(yīng)中斷 [8]。 TMOD=0x01。 EA=1。 )。程序應(yīng)按照嚴(yán)格的時(shí)序進(jìn)行，以保證數(shù)據(jù)的完整性。單片機(jī)與溫度傳感器之間采用單總線通信標(biāo)準(zhǔn)，用簡(jiǎn)單、高效的通信電路實(shí)現(xiàn)檢測(cè)數(shù)據(jù)的讀取。本設(shè)計(jì)中由于采用了 AT89C51 單片機(jī)，性能可靠電路簡(jiǎn)單，適于批量生產(chǎn), 而且溫度傳感器 DS18B20 轉(zhuǎn)化溫度的方法非常簡(jiǎn)潔且精度高、測(cè)試范圍較廣。電路詳解[M].北京:電子工業(yè)出版社,1993[4] 在分布式測(cè)溫系統(tǒng)中的應(yīng)用[J].北京：淮陰工學(xué)學(xué)報(bào)，2022 [5] . [6] ，高等教育出版社[7] [M].上海：電子工業(yè)出版社,2022[8] [M].北京：清華大學(xué)出版社，2022附錄 A 軟件仿真圖附圖1 軟件仿真圖附錄 B 系統(tǒng)程序include include //_nop_()。//共陰數(shù)碼管顯示 0~F /* 共陰 LED 段碼表 0 1 2 3 4 5 6 7 8 9 不亮 */ uchar code ditab[16]={0,1,1,2,3,3,4,4,5,6,6,7,8,8,9,9}。uint h,i=0。t0。} } /***********11 微秒延時(shí)函數(shù) ****溫度用******************///void delay0(uint t){for(。 //段碼//P0=0X7F。 //段碼P0=0X1F。 //段碼P0=0X3F。 //段碼P0=0X5F。 //段碼P0=0X7F。for(i。 //選擇數(shù)碼管 2Delay(2)。 // 消隱 }*/ } /***********18B20 復(fù)位函數(shù)**********/ow_reset(void){char presence=1。DQ=0。 // 66uspresence=DQ。} ///**********18B20 寫命令函數(shù)*********///向 1WIRE 總線上寫一個(gè)字節(jié)void write_byte(uchar val){uchar i。_nop_()。_nop_()。//5usDQ = valamp。 //右移一位}DQ = 1。for (i=8。_nop_()。_nop_()。_nop_()。 //4us if(DQ)value|=0x80。}/***********讀出溫度函數(shù)**********/read_temp(){ow_reset()。 //溫度低 8 位temp_data[1]=read_byte()。 // 發(fā)送轉(zhuǎn)換命令}/***********溫度數(shù)據(jù)處理函數(shù)**********/void work_temp(){uchar n=0。0xf8)!=0x00){ temp_data[1]=~(temp_data[1])。 }display[4]=temp_data[0]amp。dotl=display[0]%10。display[3]=display[4]/100。//負(fù)溫度時(shí)最高位顯示 flag3=0。h25。h4。 // Skip ROMwrite_byte(0x44)。//開機(jī)顯示88881 秒 while(1){ wendu()。在此祝愿老師身體健康，工作順利。t charge you more than 35% of your pensation if you win the case.If you are thinking about signing up for a damagesbased agreement, you should make sure you39。s Premier League match at Chelsea on Sunday.I am going to be at the match tomorrow and I have asked to meet Yaya Toure, he told BBC Sport.For me it39。s actions.CSKA said they were surprised and disappointed by Toure39?？傆X得自己自己似乎應(yīng)該去做點(diǎn)什么，或者寫點(diǎn)什么。t really grow up, it seems is not so important。Originally, this world, can produce a chemical reaction to an event, in addition to resolutely, have to do, and time.　 　 原來，這個(gè)世界上，對(duì)某個(gè)事件能產(chǎn)生化學(xué)反應(yīng)的，除了非做不可的堅(jiān)決，還有，時(shí)間。也曾經(jīng)好像已經(jīng)下定了決心去做某件事，但更多的時(shí)候是最后又打起了退堂鼓。 Those were broken into various shapes of stationery。突然想到那件藍(lán)格子襯衫；那些被折成各種各樣形狀的信紙；那段從街角深巷伊始的友誼；還有那場(chǎng)還沒有開始就宣告了終結(jié)的邂逅計(jì)劃……那些年那些天的非做不可，終于和青春一樣，都將在我們的人生中謝幕。t. Baumgartner still will free fall at a speed that would cause you and me to pass out, and no parachute is guaranteed to work higher than 25,000 feet (7,620 meters).cause there。ll be traveling fast, so despite the distance, it will not be like diving into the deep end of a pool. It will be like he is diving into the shallow end. Skydiver preps for the big jumpWhen he jumps, he is expected to reach the speed of sound 690 mph (1,110 kph) in less than 40 seconds. Like hitting the top of the water, he will begin to slow as he approaches the more dense air closer to Earth. But this will not be enough to stop him pletely.If he goes too fast or spins out of control, he has a stabilization parachute that can be deployed to slow him down. His team hopes it39。 Have declared the end of the encounter that haven39。那些曾經(jīng)所謂的非做不可，只是青蔥年華里自己給自己注射的一支強(qiáng)心劑，或者說，是自以為是的精神寄托罷了。s time, your ideas are always special to clear. Want, want, line is clear, as if nothing could shake his. Also once seemed to be determined to do something, but more often is he backed out at last. Dislike his cowardice, finally found that there are a lot of love, there are a lot of miss, like shadow really have been doomed. Those who do, just green years oneself give oneself an arm injection, or is a selfrighteous spiritual.　 　 一個(gè)人的時(shí)候，自己的想法總是特別地清晰。t want to give vent to out your inner voice can be in the high school children of the feelings in a period, but was eventually infarction when graduation party in the throat, later again stood on the pitch he has sweat profusely, looked at his thrown a basketball hoops, suddenly found himself has already can39。The end of our life, and can meet many things really do?　 　 而窮盡我們的一生，又能遇到多少事情是真正地非做不可？During my childhood, think lucky money and new clothes are necessary for New Year, but as the advance of the age, will be more and more found that those things are optional。 May be back in the past, to oneself the paranoid weird belief disillusionment, these days, my mind has been very messy, in my mind constantly. Always feel oneself should go to do something, or write something. Twenty years of life trajectory deeply shallow, suddenly feel something, do it.　 　 一字開頭的年齡已經(jīng)到了尾聲。s 21 win.Michel Platini, president of European football39。s antiracism taskforce, is in London for the Football Association39。t agree with the disciplinary action your employer has taken against you? your employer dismisses you and you think that you have been dismissed unfairly.For more information about dismissal and unfair dismissal, see Dismissal.You can make a claim to an employment tribunal, even if you haven39。導(dǎo)師嚴(yán)謹(jǐn)?shù)闹螌W(xué)態(tài)度、敏銳的直覺和對(duì)科學(xué)的執(zhí)著追求都深深的影響了我，她對(duì)我的嚴(yán)格要求讓我學(xué)到了知識(shí)，掌握了科研的方法，也獲得了實(shí)踐鍛煉的機(jī)會(huì)。h120。}//開機(jī)顯示 8888ow_reset()。 //顯示溫度值 秒(H=250) } }