【正文】 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 28diving 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。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(méi)有開(kāi)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。 Have declared the end of the encounter that haven39。 Those were broken into various shapes of stationery。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(shuō)，是自以為是的精神寄托罷了。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。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。Originally, this world, can produce a chemical reaction to an event, in addition to resolutely, have to do, and time.　 　 原來(lái)，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。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 really grow up, it seems is not so important。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。總覺(jué)得自己自己似乎應(yīng)該去做點(diǎn)什么，或者寫(xiě)點(diǎn)什么。 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(kāi)頭的年齡已經(jīng)到了尾聲。s actions.CSKA said they were surprised and disappointed by Toure39。s 21 win.Michel Platini, president of European football39。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 antiracism taskforce, is in London for the Football Association39。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。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。這次課程設(shè)計(jì)終于順利完成了，在設(shè)計(jì)中遇到了很多編程問(wèn)題，最后在宋陽(yáng)老師的辛勤指導(dǎo)下，終于游逆而解。通過(guò)這次課程設(shè)計(jì)使我懂得了理論與實(shí)際相結(jié)合是很重要的，只有理論知識(shí)是遠(yuǎn)遠(yuǎn)不夠的，只有把所學(xué)的理論知識(shí)與實(shí)踐相結(jié)合起來(lái)，從理論中得出結(jié)論，才能真正為社會(huì)服務(wù)，從而提高自己的實(shí)際動(dòng)手能力和獨(dú)立思考的能力。因此作為二十一世紀(jì)的大學(xué)來(lái)說(shuō)掌握單片機(jī)的開(kāi)發(fā)技術(shù)是十分重要的。如果選擇的是方波，則用查表的方法求出相應(yīng)的數(shù)據(jù)，并通過(guò) D/A 轉(zhuǎn)換器將數(shù)據(jù)轉(zhuǎn)換成模擬信號(hào)，形成所需波形信號(hào)。圖 主程序流程圖 1114圖 為各波形子程序的流程圖。主程序的流程圖如圖 所示，在程序開(kāi)始運(yùn)行之后，首先是對(duì) 8155 進(jìn)行初始化，之后判斷信號(hào)頻率值，如符合所需的頻率，則重置時(shí)間常數(shù)，并通過(guò)顯示器顯示出來(lái)，不符則返回。其器件模型如圖 所示。 圖 時(shí)鐘電路9 顯示電路顯示電路是用來(lái)顯示波形信號(hào)的頻率，使得整個(gè)系統(tǒng)更加合理，從經(jīng)濟(jì)的角度出發(fā)，所以顯示器件采用 LED 數(shù)碼管顯示器。電容 CC2 對(duì)振蕩頻率有穩(wěn)定作用，其容量的選擇為 30pf，振蕩器選擇頻率為 12MHz 的石英晶體。 “S3”號(hào)鍵代表鋸齒波輸出， “S4”號(hào)鍵為10Hz 的頻率信號(hào)， “S5”號(hào)鍵為 100Hz 的頻率信號(hào)， “S6”號(hào)鍵為 500Hz 的頻率信號(hào)， “S7”號(hào)鍵為 1KHz 的頻率信號(hào) [3]。圖 數(shù)模轉(zhuǎn)換電路 按鍵接口電路1230UR??8圖 為鍵盤(pán)接口電路的原理圖，圖中鍵盤(pán)和 8155 的 PA 口相連，AT89C51 的P0 口和 8155 的 D0 口相連，AT89C51 不斷的掃描鍵盤(pán)，看是否有鍵按下，如有，則根據(jù)相應(yīng)按鍵作出反應(yīng)。由圖 可知，DAC0832 的片選地址為 7FFFH，當(dāng) P25 有效時(shí)，若 P0 口向其送的數(shù)據(jù)為 00H， 則 U1 的輸出電壓為 0V。但實(shí)際上， DAC0832 輸出的電量也不是真正能連續(xù)可調(diào)，而是以其絕對(duì)分辨率為單位增減，是準(zhǔn)模擬量的輸出。單片機(jī)鍵盤(pán)電路顯示電路復(fù)位電路數(shù)/模轉(zhuǎn)換電路放大電路波形輸出7圖 主控電路圖 數(shù)/模轉(zhuǎn)換電路由于單片機(jī)產(chǎn)生的是數(shù)字信號(hào)，要想得到所需要的波形，就要把數(shù)字信號(hào)轉(zhuǎn)換成模擬信號(hào)，所以該文選用價(jià)格低廉、接口簡(jiǎn)單、轉(zhuǎn)換控制容易并具有 8 位分辨率的數(shù)模轉(zhuǎn)換器 DAC0832。如果有鍵按下，則在讀控制端會(huì)產(chǎn)生一個(gè)讀信號(hào)，使單片機(jī)讀入信號(hào)。在波形發(fā)生器中，只用到片內(nèi)定時(shí)器／計(jì)數(shù)器溢出時(shí)產(chǎn)生的中斷請(qǐng)求，即是在 AT89C51 輸出一個(gè)波形采樣點(diǎn)信號(hào)后，接著啟動(dòng)定時(shí)器，在定時(shí)器未產(chǎn)生中斷之前，AT89C51 等待，直到定時(shí)器計(jì)時(shí)結(jié)束，產(chǎn)生中斷請(qǐng)求，AT89C51 響應(yīng)中斷，接著輸出下一個(gè)采樣點(diǎn)信號(hào)，如此循環(huán)產(chǎn)生所需要的信號(hào)波形[6]。中斷系統(tǒng)是使處理器具有對(duì)外界異步事件的處理能力而設(shè)置的。在波形發(fā)生器中，將其作定時(shí)器使用，用它來(lái)精確地確定波形的兩個(gè)采樣點(diǎn)輸出之間的延遲時(shí)間。(sin1)25(25)/tDiYA????? 7第三章 硬件設(shè)計(jì) 硬件原理框圖硬件原理方框圖如圖 所示。（4）頻率范圍：10~1000Hz 。（2） “S4”號(hào)鍵為 10Hz 的頻率信號(hào)， “S5”號(hào)鍵為 100Hz 的頻率信號(hào)，“S6”號(hào)鍵為 500Hz 的頻率信號(hào)， “S7”號(hào)鍵為 1KHz 的頻率信號(hào)，6 個(gè) LED 顯示器輸出信號(hào)的頻率值，選用共陽(yáng)極 LED。 設(shè)計(jì)功能（1）本方案利用 8155 擴(kuò)展 8 個(gè)獨(dú)立式按鍵，6 個(gè) LED 顯示器。（2）將一個(gè)周期的信號(hào)分離成 256 個(gè)點(diǎn)（按 X 軸等分） ，每?jī)牲c(diǎn)之間的時(shí)間間隔為 T，用單片機(jī)的定時(shí)器產(chǎn)生，其表示式為： T=T/256。當(dāng)數(shù)字信號(hào)89C51單片機(jī)接口電路D/A轉(zhuǎn)換器濾波放大 輸出 4經(jīng)過(guò)接口電路到達(dá)轉(zhuǎn)換電路，將其轉(zhuǎn)換成模擬信號(hào)也就是所需要的輸出波形。89C51 單片機(jī)本身就是一個(gè)完整的微型計(jì)算機(jī)，具有組成微型計(jì)算機(jī)的各部分部件：中央處理器 CPU、隨機(jī)存取存儲(chǔ)器RAM、只讀存儲(chǔ)器 ROM、I/O 接口電路、定時(shí)器/計(jì)數(shù)器以及串行通訊接口等，只要將 89C51 再配置鍵盤(pán)及其接口、顯示器及其接口、數(shù)模轉(zhuǎn)換及波形輸出、指示燈及其接口等四部分，即可構(gòu)成所需的波形發(fā)生器，其信號(hào)發(fā)生器構(gòu)成原理框圖如圖 所示。它不僅采用軟硬件結(jié)合，軟件控制硬件的方法來(lái)實(shí)現(xiàn)，