畢業(yè)設(shè)計(jì)基于STC89C51單片機(jī)的信號(hào)發(fā)生器的設(shè)計(jì)與實(shí)現(xiàn)【完整電路、程序】

1、 摘 要本文以stc89c51單片機(jī)為核心設(shè)計(jì)了一個(gè)低頻函數(shù)信號(hào)發(fā)生器。信號(hào)發(fā)生器采用數(shù)字波形合成技術(shù),通過硬件電路和軟件程序相結(jié)合,可輸出自定義波形,如正弦波、方波、三角波、三角波、梯形波及其他任意波形，波形的頻率和幅度在一定范圍內(nèi)可任意改變。波形和頻率的改變通過軟件控制，幅度的改變通過硬件實(shí)現(xiàn)。介紹了波形的生成原理、硬件電路和軟件部分的設(shè)計(jì)原理。本系統(tǒng)可以產(chǎn)生最高頻率798.6hz的波形。該信號(hào)發(fā)生器具有體積小、價(jià)格低、性能穩(wěn)定、功能齊全的優(yōu)點(diǎn)。關(guān)鍵詞:低頻信號(hào)發(fā)生器;單片機(jī);d /a轉(zhuǎn)換; 1設(shè)計(jì)選題及任務(wù)設(shè)計(jì)題目：基于單片機(jī)的信號(hào)發(fā)生器的設(shè)計(jì)與實(shí)現(xiàn) 任務(wù)與要求：設(shè)計(jì)一個(gè)由單片機(jī)控制的信

2、號(hào)發(fā)生器。運(yùn)用單片機(jī)系統(tǒng)控制產(chǎn)生多種波形，這些波形包括方波、三角波、鋸齒波、正弦波等。信號(hào)發(fā)生器所產(chǎn)生的波形的頻率、幅度均可調(diào)節(jié)。并可通過軟件任意改變信號(hào)的波形?；疽螅?.產(chǎn)生三種以上波形。如正弦波、三角波、矩形波等。 2.最大頻率不低于 500hz。并且頻率可按一定規(guī)律調(diào)節(jié)，如周期按1t,2t,3t,4t或1t，2t，4t，8t變化。 3.幅度可調(diào)，峰峰值在05v之間變化。 擴(kuò)展要求：產(chǎn)生更多的頻率和波形。 2系統(tǒng)概述2.1方案論證和比較211總體方案：方案一：采用模擬電路搭建函數(shù)信號(hào)發(fā)生器，它可以同時(shí)產(chǎn)生方波、三角波、正弦波。但是這種模塊產(chǎn)生的不能產(chǎn)生任意的波形（例如梯形波），并且頻率

3、調(diào)節(jié)很不方便。方案二：采用鎖相式頻率合成器，利用鎖相環(huán)，將壓控振蕩器（vco）的輸出頻率鎖定在所需頻率上，該方案性能良好，但難以達(dá)到輸出頻率覆蓋系數(shù)的要求，且電路復(fù)雜。方案三：使用集成信號(hào)發(fā)生器發(fā)生芯片，例如ad9854,它可以生成最高幾十mhz的波形。但是該方案也不能產(chǎn)生任意波形（例如梯形波），并且價(jià)格昂貴。方案四：采用at89c51單片機(jī)和dac0832數(shù)模轉(zhuǎn)換器生成波形，加上一個(gè)低通濾波器，生成的波形比較純凈。它的特點(diǎn)是可產(chǎn)生任意波形，頻率容易調(diào)節(jié)，頻率能達(dá)到設(shè)計(jì)的500hz以上。性能高，在低頻范圍內(nèi)穩(wěn)定性好、操作方便、體積小、耗電少。經(jīng)比較，方案四既可滿足課程設(shè)計(jì)的基本要求又能充分發(fā)揮

4、其優(yōu)勢(shì)，電路簡(jiǎn)單，易控制，性價(jià)比高，所以采用該方案.212改變幅度方案：方案一：可以將送給da的數(shù)字量乘以一個(gè)系數(shù)，這樣就可以改變da輸出電流的幅度，從而改變輸出電壓；但是這樣做有很嚴(yán)重的問題，單片機(jī)在做乘法運(yùn)算時(shí)需要很長(zhǎng)的時(shí)間，這樣的話輸出波形的頻率就會(huì)很低，達(dá)不到至少500hz的要求；并且該方案的輸出電壓做不到連續(xù)可調(diào)，當(dāng)da的輸入數(shù)字量比較小時(shí)，輸出的波形失真就會(huì)比較嚴(yán)重。方案二：將輸出電壓通過一個(gè)運(yùn)算放大器的放大。這樣還有個(gè)優(yōu)點(diǎn)是幅度連續(xù)可調(diào)。經(jīng)比較，方案二既可滿足課程設(shè)計(jì)的基本要求，并且電路也挺簡(jiǎn)單。2.2工作原理數(shù)字信號(hào)可以通過數(shù)/模轉(zhuǎn)換器轉(zhuǎn)換成模擬信號(hào)，因此可通過產(chǎn)生數(shù)字信號(hào)再轉(zhuǎn)

5、換成模擬信號(hào)的方法來獲得所需要的波形。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再配置鍵盤及、數(shù)模轉(zhuǎn)換及波形輸出、放大電路等部分，即可構(gòu)成所需的波形發(fā)生器，其信號(hào)發(fā)生器構(gòu)成系統(tǒng)框圖如下圖所示。系統(tǒng)框圖89c51是整個(gè)波形發(fā)生器的核心部分，通過程序的編寫和執(zhí)行，產(chǎn)生各種各樣的信號(hào)，并從鍵盤接收數(shù)據(jù)，進(jìn)行各種功能的轉(zhuǎn)換和信號(hào)幅度的調(diào)節(jié)。當(dāng)數(shù)字信號(hào)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。波形rom表是將信號(hào)一個(gè)周期等間距地

6、分離成64個(gè)點(diǎn)，儲(chǔ)存在單片機(jī)得ron內(nèi)。具體rom表是通過matlab生成的，例如正弦表，matlab生成的程序如下：x=0:2*pi/64:2*pi; y=round(sin(x)*127)+1283單元電路設(shè)計(jì)與分析3.1.1主控電路設(shè)計(jì)中主要采用stc89c51型單片機(jī)，它具有如下優(yōu)點(diǎn)：（1）擁有完善的外部擴(kuò)展總線，通過這些總線可方便地?cái)U(kuò)展外圍單元、外圍接口等。（2）該單片機(jī)內(nèi)部擁有4k字節(jié)的flash rom程序存儲(chǔ)器空間和256字節(jié)的ram數(shù)據(jù)存儲(chǔ)空間，完全可以滿足程序的要求。由于該芯片可電擦寫，故可重復(fù)使用。如果更改程序內(nèi)容，可將芯片拿下重新燒寫。（3）該單片機(jī)與工業(yè)標(biāo)準(zhǔn)的mcs5

7、1型機(jī)的指令集和輸出引腳兼容。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。當(dāng)中央處理器cpu正在處理某件事的時(shí)候外界發(fā)生了緊急事件，要求cpu暫停當(dāng)前的工作，轉(zhuǎn)而去處理這個(gè)緊急事件。在波形發(fā)生器中，用兩個(gè)開光直接與外部中斷0和外部中斷1的管腳相連，其中s1開光用來改變波形，s2開光用來改變頻率。在程序主函數(shù)中，我們寫了個(gè)死循環(huán)一直輸出一個(gè)默認(rèn)的波形，當(dāng)s1或s2按下又抬起時(shí)，程序會(huì)暫時(shí)跳出死循環(huán)，進(jìn)入中斷處理程序，從而對(duì)波形和頻率進(jìn)行改變。時(shí)鐘電路。由于頻率較大時(shí)，三角波、正弦波、方波等波中每一點(diǎn)延時(shí)時(shí)間為幾微秒，故延時(shí)時(shí)間還要加上指令時(shí)間即可得到指定頻率的波形，該電路用11.05

8、92mhz晶振。 主控電路圖3.1.2 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。dac0832主要由8位輸入寄存器、8位dac寄存器、8位d/a轉(zhuǎn)換器以及輸入控制電路四部分組成。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。dac0832是電流型輸出，在應(yīng)用時(shí)外接運(yùn)放使之成為電壓型輸出。根據(jù)對(duì)dac0832的數(shù)據(jù)鎖存器和dac寄存器的不同的控制方式，dac0832有三種工作方式：直通方式、單緩沖方

9、式和雙緩沖方式。本設(shè)計(jì)選用直通方式。dac0832的數(shù)據(jù)口和單片機(jī)的p0口相連。csda：片選信號(hào)輸入線（選通數(shù)據(jù)鎖存器），低電平有效；wr：數(shù)據(jù)鎖存器寫選通輸入線，負(fù)脈沖（脈寬應(yīng)大于500ns）有效。由ile、cs、wr1的邏輯組合產(chǎn)生le1，當(dāng)le1為高電平時(shí)，數(shù)據(jù)鎖存器狀態(tài)隨輸入數(shù)據(jù)線變換，le1的負(fù)跳變時(shí)將輸入數(shù)據(jù)鎖存；數(shù)模轉(zhuǎn)換電路3.1.3運(yùn)算放大電路和低通濾波電路lm324的5管腳與dac0832的（iout2）12管腳相連，lm324的6管腳與dac0832的（iout1）11管腳相連，lm324的7管腳與dac0832的ref（9）管腳相連.第一級(jí)運(yùn)算放大器的作用是將dac08

10、32輸出的電流信號(hào)轉(zhuǎn)化為電壓信號(hào)v1，第二級(jí)運(yùn)算放大器的作用是將v1通過反向放大電路-（r2/r1）倍。題目要求輸出的電壓在0-5v可調(diào)，而v1的電壓大約是5v，所以r1選擇5k的電阻，r2選擇10k的電位器，這樣最大的輸出電壓為5*（10/2）=10，最小電壓為0，可以實(shí)現(xiàn)題目要求的0-5v。在第二個(gè)運(yùn)算放大器的輸出端連了一個(gè)低通濾波器。如果不加低通濾波器，也能夠生成波形，但是產(chǎn)生的信號(hào)中毛刺很多，加一個(gè)低通濾波器不僅起到的濾波的作用，還起到了平滑的作用。低通濾波器的截止頻率f=1/(2*pi*r3*c6),這里我們選擇r3 為100歐姆電阻，c6為104電容，截止頻率f=16khz。實(shí)驗(yàn)表

11、明，此時(shí)的輸出波形效果不錯(cuò)。3.1.4 串口通信電路通用異步收發(fā)器(uart)是一種串行接口，一般微處理器中都包含這種外設(shè)接口。異步串行接口提供了一種簡(jiǎn)單的途徑，使兩個(gè)器件無(wú)需共享同一個(gè)時(shí)鐘信號(hào)就能進(jìn)行通信。如果再加入一個(gè)合適的電平轉(zhuǎn)換器max232，串口就能能用在rs232和rs485等網(wǎng)絡(luò)中實(shí)現(xiàn)通信，或者與計(jì)算機(jī)的com端口連接。串口只需兩根信號(hào)線(rx和tx)即可實(shí)現(xiàn)，而且只要兩端器件都采用同樣的位格式和波特率，那么它們無(wú)需其它任何對(duì)方的信息就可以成功傳輸數(shù)據(jù)。串口通信電路圖3.2系統(tǒng)軟件設(shè)計(jì)軟件設(shè)計(jì)上，根據(jù)功能分了幾個(gè)模塊編程。模塊主要有：主程序模塊、外部中斷0模塊，外部中斷1模塊。主

12、程序：主程序先是進(jìn)行一些初始化的工作，然后根據(jù)波形標(biāo)志a,b,c,d,e的值進(jìn)入相應(yīng)的while 循環(huán)。這樣寫的好處是輸出的波形頻率可以790多hz。在while循環(huán)中，單片機(jī)根據(jù)地址標(biāo)志位不停低查表，然后把查得的值賦給dac0832的數(shù)據(jù)口，然后地址標(biāo)志位加一，并判斷地址標(biāo)志位是否等于64，如果是就置0再往下執(zhí)行，如果不是直接往下執(zhí)行。然后根據(jù)頻率標(biāo)志位進(jìn)行相應(yīng)的延時(shí)。主程序流程圖中斷服務(wù)程序：本程序中兩個(gè)外部中斷分別起到了控制波形和頻率的作用。在程序中還加入了消抖部分。4安裝調(diào)試及測(cè)量數(shù)據(jù)分析4.1調(diào)試過程;1 不通電，用萬(wàn)用表根據(jù)電路圖仔細(xì)檢查各線路連接是否正常。2 首先是調(diào)試單片機(jī)部分

13、，da和運(yùn)算放大器芯片不接。用stc_isp_v483軟件通過串口下程序?？词欠窨梢哉Ｏ鲁绦?。3當(dāng)可以正常下程序時(shí)，給51單片機(jī)下一個(gè)讓所有i/0口一會(huì)兒輸入0，延時(shí)，再輸出1，以此類推。用萬(wàn)用表測(cè)量各i/o口得電壓是不是一會(huì)兒高，一會(huì)兒低。4安上da和運(yùn)算放大器芯片，給單片機(jī)下一個(gè)輸出正弦波的測(cè)試程序，通過示波器看輸出是否正常。5 給單片機(jī)下一個(gè)完整的程序，分別按下s1，看波形是否改變。按下s2，看頻率是否改變。4.2頻率的測(cè)量數(shù)據(jù)： 單位：hz周期t2t3t4t5t6t7t8t理論值798.6399.3266.2199.7159.7133.1114.199.8實(shí)際值798.6399.62

14、66.5199.9159.9133.3114.299.94.3出現(xiàn)的問題與解決的方法：1.調(diào)試單片機(jī)的串口時(shí)，發(fā)現(xiàn)不能正常的下程序。我想可能是單片機(jī)壞了借了一塊學(xué)習(xí)板測(cè)試了一下單片機(jī)芯片，發(fā)現(xiàn)可以正常下載。這說明很可能是max232的電路出了問題。我仔細(xì)查看了電路圖，又上網(wǎng)查了下其他的max232的電路圖，發(fā)現(xiàn)我的電路圖和別人的不一樣。我是按照郭天翔的那本新概念51單片機(jī)c語(yǔ)言教程 入門、提高、開發(fā)、拓展全第130頁(yè)的串口電路畫的圖，電路圖中max232的tiou1接串口的第3腳。而其他書上有些電路圖卻是max232的tiou1接到了串口的第2腳。于是我將max232的tiou1接串口的第2腳

15、，再下程序，終于可以正常下載了。2剛開始寫的測(cè)試程序輸出的波形失真很大。我想可能是波形的rom表里的數(shù)據(jù)值過小，導(dǎo)致da輸出的誤差很大。因而臥將波形的rom表里的數(shù)據(jù)值調(diào)大，在測(cè)試時(shí)發(fā)現(xiàn)波形變得好多了。3.調(diào)試波形的時(shí)候我發(fā)現(xiàn)矩形波的失真比較大。我想到可能是低通濾波器的截止頻率太低了，因而我將rc低通濾波器的電阻由1k換成了100歐姆，效果好了很多。4.4系統(tǒng)仿真波形：矩形波鋸齒波正弦波4.5效果分析：由4.2的頻率理論值與實(shí)際值，可知頻率在t,2t,3t,4t,5t,6t,7t,8t上頻率誤差很小。最終的波形輸出效果也很不錯(cuò)。4.6測(cè)量?jī)x器示波器 直流穩(wěn)壓電源萬(wàn)用表5結(jié)束語(yǔ)基于單片機(jī)的信號(hào)發(fā)

16、生器設(shè)計(jì)，這個(gè)信號(hào)發(fā)生器的設(shè)計(jì)中涉及到一個(gè)典型的控制過程。通過單片機(jī)控制一個(gè)模數(shù)轉(zhuǎn)換器dac0832產(chǎn)生所需要的電流，然后使用運(yùn)算放大器lm324可以將其電流輸出線性地轉(zhuǎn)換成電壓輸出，再將電壓經(jīng)過運(yùn)算放大器的放大，可以得到足夠幅度的信號(hào)。通過程序的控制，可以產(chǎn)生一系列有規(guī)律的波形。這樣一個(gè)信號(hào)發(fā)生裝置在控制領(lǐng)域有相當(dāng)廣泛的應(yīng)用范圍。最終做出來的信號(hào)發(fā)生器滿足了題目中的所有要求：1.產(chǎn)生五種波形。正弦波、三角波、矩形波、梯形波，鋸齒波。 2.最大頻率為798.6hz。并且頻率可按按1t,2t,3t,4t,5t,6t,7t,8t變化。3.幅度可調(diào)，峰峰值在05v之間變化。 當(dāng)然還是存在不足的地方，

17、比如不能實(shí)現(xiàn)頻率的按一個(gè)小的步進(jìn)調(diào)整。并且當(dāng)頻率太小時(shí)矩形波會(huì)有些失真。信號(hào)發(fā)生器可以生成更多的波形，只需要再加些波形表即可。在這里得感謝學(xué)校為我們提供個(gè)這樣一個(gè)實(shí)踐的機(jī)會(huì)，當(dāng)然還得感謝實(shí)驗(yàn)室指導(dǎo)老師們的細(xì)心指導(dǎo)。參考文獻(xiàn)：1 郭天翔.新概念51單片機(jī)c語(yǔ)言教程 入門、提高、開發(fā)、拓展全.北京.電子工業(yè)出版社 2009.12 童詩(shī)白.模擬電路技術(shù)基礎(chǔ)m.北京：高等教育出版社，2000.171202.附錄1：總電路圖18附錄2：源程序#include#define uchar unsigned char#define uint unsigned intsbit csda=p22;sbit wr=

18、p21;sbit s1=p32;sbit s2=p33;uchar k=0,p=0,delay=0;uchar bxxz=0;pinglv=0;uchar a=1,b=0,c=0,d=0,e=0;uchar code sin64=135,145,158,167,176,188,199,209,218,226,234,240,245,249,252,254,254,253,251,247,243,237,230,222,213,204,193,182,170,158,146,133,121,108,96,84,72,61,50,41,32,24,17,11,7,3,1,0,0,2,5,9,14,

19、20,28,36,45,55,66,78,90,102,114,128;uchar code juxing64=255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0;uchar code juchi64=0,4,8,12,16,20,24,28,32,36,40,45,

20、49,53,57,61,65,69,73,77,81,85,89,93,97,101,105,109,113,117,121,125,130,134,138,142,146,150,154,158,162,166,170,174,178,182,186,190,194,198,202,206,210,215,219,223,227,231,235,239,243,247,251,255;uchar code tixing64=0,13,26,39,52,65,78,91,104,117,130,143,156,169,182,195,208,221,234,247,247,247,247,24

21、7,247,247,247,247,247,247,247,247,247,247,247,247,247,247,247,247,247,247,247,247,247,242,229,216,203,190,177,164,151,138,125,112,99,86,73,60,47,34,21,8;uchar code sanjiao64=0,8,16,24,32,40,48,56,64,72,80,88,96,104,112,120,128,136,144,152,160,168,176,184,192,200,208,216,224,232,240,248,248,240,232,2

22、24,216,208,200,192,184,176,168,160,152,144,136,128,120,112,104,96,88,80,72,64,56,48,40,32,24,16,8,0;void delay1()int a,b;for(a=1;a0;a-)for(b=122;b0;b-);void int0() interrupt 0ex0=0;delay1();if(s1=0)bxxz+;if(bxxz=5)bxxz=0;switch(bxxz)case 0 :a=1,b=0,c=0,d=0,e=0;break;case 1 :a=0,b=1,c=0,d=0,e=0;break

23、;case 2 :a=1,b=0,c=1,d=0,e=0;break;case 3 :a=0,b=0,c=0,d=1,e=0;break;case 4 :a=0,b=0,c=0,d=0,e=1;break;delay1();while(!s1);while(!s1);ex0=1;void int1() interrupt 2ex1=0;delay1();if(s2=0)p+;if(p=8) p=0;switch(p)case 1 :pinglv=3;break;case 2 :pinglv=6;break;case 3 :pinglv=9;break;case 4 :pinglv=12;bre

24、ak;case 5 :pinglv=15;break;case 6 :pinglv=18;break;case 7 :pinglv=21;break;default :pinglv=0;break;delay1();while(!s2);while(!s2);ex1=1;void main()csda=0;wr=0;ea=1;it0=1;ex0=1;it1=1;ex1=1;while(1)while(a) delay=pinglv;p0=sink;k+;if(k=64)k=0;while(delay) delay-;while(b) delay=pinglv;p0=juxingk;k+;if(

25、k=64)k=0;while(delay) delay-;while(c) delay=pinglv;p0=juchik;k+;if(k=64)k=0;while(delay) delay-;while(d) delay=pinglv;p0=tixingk;k+;if(k=64)k=0;while(delay) delay-;while(e) delay=pinglv;p0=sanjiaok;k+;if(k=64)k=0;while(delay) delay-;g an employment tribunal claiemployment tribunals sort out disagree

26、ments between employers and employees.you may need to make a claim to an employment tribunal if: you dont 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 un

27、fair dismissal, seedismissal.you can make a claim to an employment tribunal, even if you haventappealedagainst the disciplinary action your employer has taken against you. however, if you win your case, the tribunal may reduce any compensation awarded to you as a result of your failure to appeal.rem

28、ember that in most cases you must make an application to an employment tribunal within three months of the date when the event you are complaining about happened. if your application is received after this time limit, the tribunal will not usually accept i.if you are worried about how the time limit

29、s apply to you, take advice from one of the organisations listed underfurther help.employment tribunals are less formal than some other courts, but it is still a legal process and you will need to give evidence under an oath or affirmation.most people find making a claim to an employment tribunal ch

30、allenging. if you are thinking about making a claim to an employment tribunal, you should get help straight away from one of the organisations listed underfurther help.if you are being represented by a solicitor at the tribunal, they may ask you to sign an agreement where you pay their fee out of yo

31、ur compensation if you win the case. this is known as adamages-based agreement. in england and wales, your solicitor cant charge you more than 35% of your compensation if you win the case.if you are thinking about signing up for a damages-based agreement, you should make sure youre clear about the t

32、erms of the agreement. it might be best to get advice from an experienced adviser, for example, at a citizens advice bureau. to find your nearest cab, including those that give advice by e-mail, click onnearest cab.for more information about making a claim to an employment tribunal, seeemployment tr

33、ibunals.the (lack of) air up there watch mcayman islands-based webb, the head of fifas anti-racism taskforce, is in london for the football associations 150th anniversary celebrations and will attend citys premier league match at chelsea on sunday.i am going to be at the match tomorrow and i have as

34、ked to meet yaya toure, he told bbc sport.for me its about how he felt and i would like to speak to him first to find out what his experience was.uefa hasopened disciplinary proceedings against cskafor the racist behaviour of their fans duringcitys 2-1 win.michel platini, president of european footb

35、alls governing body, has also ordered an immediate investigation into the referees actions.cska said they were surprised and disappointed by toures complaint. in a statement the russian side added: we found no racist insults from fans of cska.age has reached the end of the beginning of a word. may b

36、e guilty in his seems to passing a lot of different life became the appearance of the same day; 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 somet

37、hing. 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(gè)不同的日子過成了同一天的樣子；或許是追溯過去，對(duì)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。總覺得自己自己似乎應(yīng)該去做點(diǎn)什么，或者寫點(diǎn)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

38、，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 year

39、s later, his writing of alumni in peace, suddenly found that isnt really grow up, it seems is not so important; then in high school, think dont 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 part

40、y 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 cant remember his appearance.童年時(shí)，覺得壓歲錢和新衣服是過年必備，但是隨著年齡的推進(jìn)，會(huì)越來越發(fā)現(xiàn)，那些東西根本就可有可無(wú)；初中時(shí)，以為要有一場(chǎng)暗戀才意味著真正的成長(zhǎng)，但三年過去后，自己心平氣和的寫同學(xué)錄的時(shí)候，突然就發(fā)現(xiàn)是不是真正的成長(zhǎng)了，好像并沒有那么重要了；然后到了高

41、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(gè)句點(diǎn)，但畢業(yè)晚會(huì)的時(shí)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(chǎng)，看著他投過籃球的球框時(shí)，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(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。a persons time, your ideas are always specia

42、l 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

43、 do, just green years oneself give oneself an arm injection, or is a self-righteous spiritual.一個(gè)人的時(shí)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(dòng)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(shí)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(cuò)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(qiáng)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

44、 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 havent start planning. those years, those days of do, finally, like yout

45、h, 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(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。baumgartner the disappointing news: mission aborted. r plays an important role in this mission. starting at the ground, conditions have to be very calm - win

46、ds 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 day-to-day weather lives. it will climb higher than the tip of mount everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising altitude of commercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. as he crosses the boundary