【導(dǎo)讀】本課題要求應(yīng)用以51單片機為核心設(shè)計一自動打鈴系統(tǒng)，能完成基本計時和顯示功能，用LCD顯示時間、鈴聲可用蜂鳴器發(fā)出。方法；2）控制程序的設(shè)計及實現(xiàn)方法；3）提高學生對單片機實時控制系統(tǒng)的設(shè)計和調(diào)試能力。包括上下午標志，時、分的數(shù)字顯示，秒信號指。示，并能設(shè)置當前時間。上午8：00上課鈴：打鈴10秒、停2秒、再打鈴10秒。現(xiàn)1秒定時中斷，每產(chǎn)生一次中斷，存儲器內(nèi)相應(yīng)的秒值加1；若秒值達到60，則將其清零，并將相應(yīng)的分字節(jié)值加1；若分值達到60，則清零分字節(jié)，并將時字節(jié)值加1；若時值達到24，時處理并控制打鈴，不相同則返回主程序。時、調(diào)分、秒和強制打鈴及強制關(guān)鈴，以保證始終與標準時間相吻合。在給出地址“1”時，它利。P3口寫入“1”后，它們被內(nèi)部上拉為高電平，并用作輸入。P3口將輸出電流這是由于上拉的緣故。P3口也可作為AT89C51的一些特殊功能口，

　　

【正文】 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?；蛟S是愧疚于自己似乎把轉(zhuǎn)瞬即逝的很多個不同的日子過成了同一天的 樣子；或許是追溯過去，對自己那些近乎偏執(zhí)的怪異信念的醒悟，這些天以來，思緒一直很凌亂，在腦海中不斷糾纏?？傆X得自己自己似乎應(yīng)該去做點什么，或者寫點什么。二十年的人生軌跡深深淺淺，突然就感覺到有些事情，非做不可了。 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。 Junior high school, thought to have a crush on just means that the real growth, but over the past three years later, his writing of alumni in peace, suddenly found that isn39。t really grow up, it seems is not so important。 Then in high school, think don39。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。t remember his appearance. 童年時，覺得壓歲錢和新衣服是過年必備，但是隨著年齡的推進，會越來越發(fā)現(xiàn)，那些東西根本就可有可無；初中時，以為要有一場暗戀才意味著真正 的成長，但三年過去后，自己心平氣和的寫同學錄的時候，突然就發(fā)現(xiàn)是不是真正的成長了，好像并沒有那么重要了；然后到了高中，覺得非要吐露出自己的心聲才能為高中生涯里的懵懂情愫劃上一個句點，但畢業(yè)晚會的時候最終還是被梗塞在了咽喉，后來再次站在他曾經(jīng)揮汗如雨的球場，看著他投過籃球的球框時，突然間發(fā)現(xiàn)自己已經(jīng)想不起他的容顏。 Originally, this world, can produce a chemical reaction to an event, in addition to resolutely, have to do, and time. 原來，這個世界上，對某個事件能產(chǎn)生化學反應(yīng)的，除了非做不可的堅決，還有，時間。 A person39。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 23 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. 一個人的時候，自 己的想法總是特別地清晰。想要的，不想要的，界限明確，好像沒有什么可以撼動自己。也曾經(jīng)好像已經(jīng)下定了決心去做某件事，但更多的時候是最后又打起了退堂鼓。嫌惡過自己的怯懦，最終卻發(fā)現(xiàn)有很多 緣分 ，有很多錯過，好像冥冥之中真的已經(jīng)注定。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心劑，或者說，是自以為是的精神寄托罷了。 At the moment, the sky is dark, the air is fresh factor after just rained. Suddenly thought of blue plaid shirt。 Those were broken into various shapes of stationery。 From the corner at the beginning of deep friendship。 Have declared the end of the encounter that haven39。t start planning... Those years, those days of do, finally, like youth, will end in our life. 此刻，天空是陰暗的，空氣里有著剛下過雨之后的清新因子。突然想到那件藍格子襯衫；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；還有那場還沒有開始就宣告了終結(jié)的邂逅計劃 …… 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。 Baumgartner the disappointing news: Mission aborted. r plays an important role in this mission. Starting at the ground, conditions have to be very calm winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule attached, will move through the lower level of the atmosphere (the troposphere) where our daytoday weather lives. It will climb higher than the tip of Mount Everest ( miles/ kilometers), drifting even higher than the cruising altitude of mercial airliners ( miles/ kilometers) and into the stratosphere. As he crosses the boundary layer (called the tropopause),e can expect a lot of turbulence. The supersonic descent could happen as early as Sunda. The weatheThe balloon will slowly drift to the edge of space at 120,000 feet ( Then, I would assume, he will slowly step out onto something resembling an Olympic diving platform. Below, the Earth bees the concrete bottom of a swimming pool that he wants to land on, but not too hard. Still, he39。ll be traveling fast, so despite the distance, it will not be like diving 24 into the deep end of a pool. It will be like he is diving into the shallow end. Skydiver preps for the big jump When 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。s not needed. Instead, he plans to deploy his 270squarefoot (25squaremeter) main chute at an altitude of around 5,000 feet (1,524 meters). In order to deploy this chute successfully, he will have to slow to 172 mph (277 kph). He will have a reserve parachute that will open automatically if he loses consciousness at mach speeds. Even if everything goes as planned, it won39。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