數(shù)據(jù)記錄儀畢業(yè)設(shè)計(jì)開題報(bào)告和外文翻譯

1、<p><b>　　畢業(yè)設(shè)計(jì)附件</b></p><p>　　題目：數(shù)據(jù)記錄儀—總體方案設(shè)計(jì)，及顯示電路、軟件</p><p>　　姓　 名： </p><p>　　學(xué)　 號： </p><p>　　學(xué) 院： </p>&l

2、t;p>　　專 業(yè)： </p><p>　　指 導(dǎo) 教 師： </p><p>　　協(xié)助指導(dǎo)教師： </p><p><b>　　2009年8月7日</b></p><p><b>　　目 錄</b>&l

3、t;/p><p><b>　　畢業(yè)設(shè)計(jì)任務(wù)書1</b></p><p>　　畢業(yè)設(shè)計(jì)開題報(bào)告2</p><p>　　畢業(yè)設(shè)計(jì)外文原文及譯文6</p><p>　　畢業(yè)設(shè)計(jì)程序清單15</p><p>　　大學(xué)畢業(yè)設(shè)計(jì)（論文）任務(wù)書</p><p>　　題目： 數(shù)據(jù)記錄

4、儀—總體方案設(shè)計(jì)及顯示電路、軟件 </p><p>　　專業(yè)： 指導(dǎo)教師： </p><p>　　學(xué)院： 學(xué)號： </p><p>　　班級： 姓名：

5、 </p><p>　　一、主要內(nèi)容和基本要求</p><p>　　設(shè)計(jì)數(shù)據(jù)記錄儀總體方案、制定各個(gè)子系統(tǒng)之間的接口（包括硬件及軟件），并設(shè)計(jì)顯示部分的硬件電路及軟件程序。應(yīng)包括如下功能： </p><p>　　可以對至少3路模擬量進(jìn)行采集。</p><p>　　數(shù)據(jù)采集的時(shí)間間隔可調(diào)。</p>

6、<p>　　能夠適應(yīng)不同的模擬量形式（0-5V及4-20mA）以及不同的物理量（溫度、壓力、流量）和量程。</p><p>　　采集的數(shù)據(jù)通過USB口存入U(xiǎn)盤。</p><p>　　具有無線傳輸功能，采集的數(shù)據(jù)可以通過無線模塊傳輸給上位計(jì)算機(jī)（PC機(jī)）。</p><p><b>　　二、主要參考資料</b></p>&

7、lt;p>　　[1]胡健.單片機(jī)原理及接口技術(shù)[M].北京:機(jī)械工業(yè)出版社,2004.10 </p><p>　　[2]郭俊杰.基于USB接口的多通道數(shù)據(jù)采集儀設(shè)計(jì)[J].兵工自動化,2007.2(26) </p><p>　　[3]陳天如.計(jì)算機(jī)網(wǎng)絡(luò)與通信[J].電氣自動化,2006.3(28)</p><p>　　[4]金甌帆.單片機(jī)模擬串口的設(shè)計(jì)[D].

8、電子世界,2005(2)</p><p>　　[5]張友德.單片微型機(jī)原理、應(yīng)用和實(shí)驗(yàn)[M].上海:復(fù)旦大學(xué)出版社,2008-01-01</p><p><b>　　三、進(jìn)度要求</b></p><p><b>　　1周：完成開題報(bào)告</b></p><p>　　2-4周：完成基本電路設(shè)計(jì)</

9、p><p>　　5-10周：調(diào)試、修改</p><p>　　11-12周：英文翻譯及論文</p><p>　　13周：論文修改裝訂，準(zhǔn)備答辯</p><p><b>　　14周：答辯</b></p><p>　　大學(xué)畢業(yè)設(shè)計(jì)開題報(bào)告</p><p>　　題目：

10、 </p><p>　　專業(yè)： 指導(dǎo)教師： </p><p>　　學(xué)院： 學(xué)號： </p><p>　　班級： 姓名： </p><p>

11、;<b>　　一、課題任務(wù)與目的</b></p><p>　　課題任務(wù)：利用單片機(jī)技術(shù)，無線數(shù)傳技術(shù)，U盤存儲技術(shù)，數(shù)/模轉(zhuǎn)換技術(shù)完成一個(gè)多通道數(shù)據(jù)記錄儀。</p><p>　　課題目的：設(shè)計(jì)并完成一個(gè)新型數(shù)據(jù)記錄儀，選用一種數(shù)據(jù)存儲器從而實(shí)現(xiàn)數(shù)據(jù)記錄儀擁有大容量的存儲空間支持長時(shí)間連續(xù)的數(shù)據(jù)采集。數(shù)據(jù)以txt格式存儲在U盤中，易于在PC機(jī)上對數(shù)據(jù)進(jìn)行查看，轉(zhuǎn)存，分析

12、。 </p><p><b>　　二、調(diào)研資料情況</b></p><p><b>　　數(shù)據(jù)記錄儀的發(fā)展</b></p><p>　　數(shù)據(jù)記錄儀是一種從傳感器獲取測量結(jié)果，并將這些結(jié)果進(jìn)行存儲的電子儀器。在最簡單的形式中，技術(shù)人員將烤箱的溫度記錄在一張紙上就是數(shù)據(jù)記錄。隨著技術(shù)的發(fā)展，通過電子設(shè)備，這個(gè)過程已經(jīng)得到簡化和變

13、得比較精確、多用途和可靠。設(shè)備從簡單的存儲器發(fā)展到復(fù)雜的電腦系統(tǒng)。數(shù)據(jù)采集技術(shù)在過去40到50年以來已經(jīng)取得了很大的飛躍。舉例來說,在 50 年以前,在一個(gè)著名的學(xué)院實(shí)驗(yàn)室中,為追蹤用青銅做的坩堝中的溫度上升情況的裝置是由熱電偶、繼電器、查詢臺、一捆紙和一支鉛筆。隨著科學(xué)技術(shù)的發(fā)展，數(shù)據(jù)記錄儀也從一根鉛筆和一張紙，發(fā)展到長圖表記錄儀，再到可以使用液晶顯示器的顯示數(shù)據(jù)和圖形的數(shù)據(jù)記錄儀，經(jīng)歷了從手工到儀表，從有紙，到無紙的一個(gè)發(fā)展的過程。

14、采集速度也從最初的人工只能監(jiān)測幾個(gè)采集點(diǎn)，到現(xiàn)在每秒可以采集20萬個(gè)點(diǎn)的數(shù)據(jù)；存儲空間也在不斷的提升。</p><p><b>　　1鉛筆和紙</b></p><p>　　用鉛筆和紙的方式歷史悠久，而且它便宜、易獲得、快速和容易開始。而你所需要的就是捕捉到數(shù)字信息，然后開始用手記錄數(shù)據(jù)。不幸的是這種方法容易發(fā)生錯(cuò)誤、采集速度很慢和需要太多的人工分析。此外，它只能單通道

15、采集數(shù)據(jù)。 </p><p><b>　　2長條圖表記錄儀</b></p><p>　　現(xiàn)代多種版本的長條圖表記錄儀允許你從多個(gè)輸入取得數(shù)據(jù)。他們提供數(shù)據(jù)的長備紙記錄,因?yàn)閿?shù)據(jù)是圖解的格式,他們易于現(xiàn)場采集數(shù)據(jù)。一旦建立了長條圖表記錄儀，在沒有操作員或計(jì)算機(jī)的情況下，數(shù)記錄儀能夠自行運(yùn)轉(zhuǎn)。缺點(diǎn)是缺乏靈活性和精度低，時(shí)常限制在百分點(diǎn)。除此之外，它們的應(yīng)用受到了限制。舉例

16、來說，他們不能夠與另外的裝置輪流工作。還有就是筆和紙的維護(hù),紙的供給和數(shù)據(jù)的存儲,最重要的是紙的濫用和浪費(fèi)。但是記錄儀相當(dāng)容易建立和操作，為數(shù)據(jù)快速而簡單的分析提供永久的記錄。</p><p><b>　　3 PC機(jī)插件卡片</b></p><p>　　PC機(jī)插件卡片是單板測量系統(tǒng)，它利用ISA或PCI總線在PC機(jī)內(nèi)擴(kuò)大插槽。它們時(shí)常具有高達(dá)每秒1000點(diǎn)的閱讀速率。

17、一般是8到16個(gè)采集通道，采集的數(shù)據(jù)直接存儲在電腦里，然后進(jìn)行分析。因?yàn)榭ㄆ举|(zhì)上是計(jì)算機(jī)的一部分,建立測試是容易的。缺點(diǎn)，PC機(jī)插件卡片時(shí)常只有12字的容量,容量太小。此外,PC機(jī)內(nèi)的電子環(huán)境很容易發(fā)出噪聲、產(chǎn)生高速率的時(shí)鐘和總線噪聲，電子接觸面限制PC機(jī)插件卡片的精度。同時(shí)為了測量一些非電量輸入信號，如壓力、溫度和阻力，需要一些外部信號監(jiān)測的器件。</p><p>　　4數(shù)據(jù)電子自動記錄儀</p>

18、<p>　　數(shù)據(jù)電子自動記錄儀是典型的單機(jī)儀器，一旦配備它們, 就能測量、記錄和顯示數(shù)據(jù)而不需要操作員或計(jì)算機(jī)參與。它們能夠處理多信號輸入，有時(shí)可達(dá)120通道。 精度可與臺式 DMM 相匹敵,由于它在22字、0.004個(gè)百分率的精度范圍內(nèi)運(yùn)轉(zhuǎn)。一些數(shù)據(jù)電子自動記錄儀有能力按比例測量。使用數(shù)據(jù)電子自動記錄儀的一個(gè)好處就是他們的內(nèi)部監(jiān)測信號。大部分能夠直接地測量若干不同的輸入信號，而不需要額外的信號監(jiān)測器件。一個(gè)通道能夠監(jiān)測熱

19、電偶、溫阻器（RTD）和電壓。</p><p>　　與PC機(jī)連接容易將數(shù)據(jù)傳送到電腦進(jìn)行進(jìn)一步的分析。大多數(shù)數(shù)據(jù)電子自動記錄儀可設(shè)計(jì)為柔性和簡單的組態(tài)和操作，而且經(jīng)由電池包裹或其它方法，多數(shù)提供遠(yuǎn)程位置的操作選項(xiàng)。</p><p><b>　　4前端數(shù)據(jù)采集</b></p><p>　　前端數(shù)據(jù)采集經(jīng)常做成模塊而且是典型地與PC機(jī)或控制器連接。

20、他們被用于自動化的測試中，為其它測試裝備采集數(shù)據(jù)、控制和循環(huán)檢測信號。發(fā)送信號測試裝備的零配件。前端運(yùn)轉(zhuǎn)的效率是非常高的,能與速度和精度與最好的單機(jī)儀器匹敵。前端數(shù)據(jù)采集在很多模型里都能運(yùn)行，包括VXI版本,如Agilent E1419A 多功能測量和VXI控制模型，雖然前端器成本已經(jīng)降低,但是這些系統(tǒng)依然會非常貴,除非你需要提供高的運(yùn)轉(zhuǎn)能力.</p><p>　　近些年隨著數(shù)據(jù)采集系統(tǒng)的廣泛應(yīng)用，人們對數(shù)據(jù)記錄

21、儀的主要技術(shù)指標(biāo)，如采樣頻率、分辨率、精度、控制方式、抗干擾能力、數(shù)據(jù)存儲容量及數(shù)據(jù)傳輸方式等方面都提出了越來越高的要求。數(shù)據(jù)記錄儀也從最早的單一通道的數(shù)據(jù)采集，發(fā)展到多條采集通道，可采集多種參量，如溫度、壓力、電流、速度、張力、位移等；可輸入多種信號，如標(biāo)準(zhǔn)電流、標(biāo)準(zhǔn)電壓、頻率信號等。采樣頻率由低速向到高速迅速發(fā)展，目前可達(dá)20萬個(gè)點(diǎn)/秒。多種的儲存介質(zhì)可供選擇，存儲容量也越來越大。可以通過各種無線傳輸技術(shù)向外傳輸數(shù)據(jù)。通道間隔離，抗

22、干擾能力強(qiáng)，能在惡劣的環(huán)境下工作。</p><p><b>　　數(shù)據(jù)記錄儀的現(xiàn)狀</b></p><p>　　根據(jù)對數(shù)據(jù)記錄儀的發(fā)展的研究，不難發(fā)現(xiàn)隨著科學(xué)技術(shù)的不斷發(fā)展，用于工控現(xiàn)場的嵌入式計(jì)算機(jī)的數(shù)據(jù)采集系統(tǒng)，由于工業(yè)現(xiàn)場環(huán)境的復(fù)雜性和多樣性，對數(shù)據(jù)采集系統(tǒng)的硬件和軟件設(shè)計(jì)提出了更高的要求，小型化、易便攜，數(shù)據(jù)易轉(zhuǎn)移，具有較高的抗震動沖擊能力，兼容性和散熱性好，高

23、可靠性和可維護(hù)性等。尤其是為滿足航空、航天、遙感技術(shù)的發(fā)展和應(yīng)用需求，數(shù)據(jù)記錄儀向著超高速、超大儲存容量方面發(fā)展。出現(xiàn)了瞬態(tài)記錄的概念，超大容量的數(shù)據(jù)儲存空間已達(dá)1TB。</p><p>　　但是在另外的一些領(lǐng)域與行業(yè)中，例如煤礦里面瓦斯?jié)舛鹊臋z測，酒廠釀酒罐的溫度檢測；藥品倉庫、制藥行業(yè)、資料檔案室溫濕度的記錄；冷庫、冷藏車、食品生產(chǎn)儲藏及化工反應(yīng)釜的溫度記錄；水壓自動記錄；管道壓力記錄等等。這些參量隨時(shí)間變化

24、緩慢，測量精度要求不高，但檢測過程漫長，記錄數(shù)據(jù)可長達(dá)數(shù)月，甚至整年，即要求數(shù)據(jù)記錄儀具有超大的存儲容量。針對這種市場需求，分析目前市場上的低速數(shù)據(jù)記錄儀，存儲容量?。ㄒ话阍贛B級），數(shù)據(jù)多以HXE格式直接儲存，不便于PC機(jī)查看和分析，用戶查看數(shù)據(jù)時(shí)需要通過專用軟件對數(shù)據(jù)進(jìn)行相應(yīng)的處理后才能查看，價(jià)格昂貴等問題。</p><p><b>　　參考資料:</b></p><

25、p>　　[1]韓茜.羅豐.吳順君高速大容量固態(tài)存儲系統(tǒng)的設(shè)計(jì)[J]-雷達(dá)科學(xué)與技術(shù)2005(2)</p><p>　　[2]沈沛,戈福慶. 淺淡記錄儀的發(fā)展趨勢[J]. 中國儀器儀表, 1998, (04)</p><p>　　[3]金建祥，楊穎，郭豪杰，李杰. 無紙記錄儀──記錄儀發(fā)展新趨勢[J]. 工業(yè)儀表與自動化裝置, 1995, (04)</p><p&g

26、t;　　三、初步設(shè)計(jì)方法與實(shí)施方案</p><p>　　用戶通過鍵盤和顯示器設(shè)定系統(tǒng)時(shí)鐘，選擇所要啟動的記錄通道，設(shè)定該通道的數(shù)據(jù)量程，采集頻率和采集次數(shù)。然后啟動該通道的數(shù)據(jù)記錄。本數(shù)據(jù)采集儀，會根據(jù)用戶設(shè)定的記錄參數(shù)，進(jìn)行定時(shí)記錄。設(shè)定時(shí)間到時(shí)，記錄儀將對應(yīng)通道口的模擬量數(shù)據(jù)進(jìn)行A/D轉(zhuǎn)換后，將所轉(zhuǎn)化后所得的數(shù)字量數(shù)據(jù)根據(jù)用戶輸入的該通道量程進(jìn)行相應(yīng)的計(jì)算。得到對應(yīng)當(dāng)前數(shù)字量的實(shí)際物理值。將此物理值，通道標(biāo)號

27、，轉(zhuǎn)換的具體時(shí)間、日期轉(zhuǎn)換成相應(yīng)的ASCII碼發(fā)送到U盤中，并以txt格式儲存。轉(zhuǎn)換后的數(shù)據(jù)將被保存到相應(yīng)的文件中。</p><p>　　本數(shù)據(jù)采集儀配有無線數(shù)傳系統(tǒng)。在上位機(jī)上，通過軟件發(fā)送命令，可以隨時(shí)將已采集的數(shù)據(jù)傳送到上位機(jī)上。</p><p><b>　　1更改儲存方法</b></p><p>　　現(xiàn)在的數(shù)據(jù)記錄儀對數(shù)據(jù)的記錄多儲存于

28、數(shù)據(jù)記錄儀的內(nèi)存中，數(shù)據(jù)的查看很不方便，需要通過特殊軟件將數(shù)據(jù)傳輸?shù)接?jì)算機(jī)中。而且其數(shù)據(jù)儲存空間為固定的，這樣采集的數(shù)據(jù)量也受到了限制。</p><p>　　所以，將對數(shù)據(jù)的儲存方法進(jìn)行更改。采用U盤作為存儲器，U盤的好處在于其容量可變，不同大小的U盤所能儲存的數(shù)據(jù)量不同。當(dāng)一個(gè)U盤存儲滿了以后，只需要更換一個(gè)U盤就可以繼續(xù)進(jìn)行數(shù)據(jù)的記錄。</p><p>　　數(shù)據(jù)是以txt格式儲存到U盤

29、中，查看數(shù)據(jù)十分的方便，拔下U盤插到任何一臺計(jì)算機(jī)中就可以查看數(shù)據(jù)，對數(shù)據(jù)進(jìn)行分析。</p><p>　　經(jīng)過此改進(jìn)，可使數(shù)據(jù)記錄儀使用更加人性化，使用起來更加的方便。</p><p><b>　　2降低成本</b></p><p>　　此次所設(shè)計(jì)的數(shù)據(jù)記錄儀，采用單片機(jī)技術(shù)為核心技術(shù)，作為整個(gè)系統(tǒng)的中樞控制器，降低了一部分的制造成本。<

30、/p><p>　　由于儲存方式的改變，儲存介由擴(kuò)展內(nèi)存改為U盤存儲，降低了存儲介質(zhì)的成本。目前，基于USB2.0接口的移動存儲設(shè)備已經(jīng)被廣泛使用，尤其是采用USB-FLASH技術(shù)的U盤產(chǎn)品的容量由幾年前的16M增加到現(xiàn)在的4G以上。U盤通常是作為計(jì)算機(jī)的外部存儲設(shè)備，其造價(jià)也相對低廉，適用范圍廣闊。</p><p><b>　　四、預(yù)期結(jié)果</b></p>

31、<p>　　預(yù)期結(jié)果是完成一個(gè)具有多路數(shù)據(jù)采集的數(shù)據(jù)記錄儀，擁有至少三路的模擬量通道，可接受0-5v或4-20mA 的信號輸入，并將數(shù)據(jù)進(jìn)行數(shù)模轉(zhuǎn)換后以txt格式儲存到U盤中。 系統(tǒng)中帶有無線接收發(fā)送裝置，可通過上位機(jī)對整個(gè)儀器進(jìn)行監(jiān)控，通過無線傳輸方式將數(shù)據(jù)傳送至上位pc機(jī)。</p><p><b>　　五、進(jìn)度計(jì)劃</b></p><p><b&g

32、t;　　1周：完成開題報(bào)告</b></p><p>　　2-4周：完成基本電路設(shè)計(jì)</p><p>　　5-10周：調(diào)試、修改</p><p>　　11-12周：英文翻譯及論文</p><p>　　13周：論文修改裝訂，準(zhǔn)備答辯</p><p><b>　　14周：答辯</b><

33、/p><p>　　大學(xué)畢業(yè)設(shè)計(jì)（論文）外文原文及譯文</p><p>　　題目：數(shù)據(jù)記錄儀—總體方案設(shè)計(jì)及顯示電路、軟件 </p><p>　　專業(yè)： 指導(dǎo)教師： </p><p>　　學(xué)院：

34、 學(xué)號： </p><p>　　班級： 姓名： </p><p><b>　　外文原文</b></p><p>　　出處：http://www.usb.org/developers/docs/&

35、lt;/p><p>　　Protocol Layer</p><p>　　1.1 Byte/Bit Ordering</p><p>　　Bits are sent out onto the bus least-significant bit (LSb) first, followed by the next LSb, through to the mostsignif

36、icant bit (MSb) last. In the following diagrams, packets are displayed such that both individual bits and fields are represented (in a left to right reading order) as they would move across the bus. </p><p>

37、　　Multiple byte fields in standard descriptors, requests, and responses are interpreted as and moved over the bus in little-endian order, i.e., LSB to MSB.</p><p>　　1.2 SYNC Field</p><p>　　All p

38、ackets begin with a synchronization (SYNC) field, which is a coded sequence that generates a maximum edge transition density. It is used by the input circuitry to align incoming data with the local clock. A SYNC from an

39、initial transmitter is defined to be eight bits in length for full/low-speed and 32 bits for high-speed. Received SYNC fields may be shorter as described in Chapter 7. SYNC serves only as a synchronization mechanism and

40、is not shown in the following packet diagrams. The last</p><p>　　1.3 Packet Field Formats</p><p>　　Field formats for the token, data, and handshake packets are described in the following section

41、. Packet bit definitions are displayed in unencoded data format. The effects of NRZI coding and bit stuffing have been removed for the sake of clarity. All packets have distinct Start- and End-of-Packet delimiters. The S

42、tart-of- Packet (SOP) delimiter is part of the SYNC field.</p><p>　　1.4 Token Packets</p><p>　　Figure 8-5 shows the field formats for a token packet. A token consists of a PID, specifying either

43、 IN, OUT, or SETUP packet type and ADDR and ENDP fields. The PING special token packet also has the same fields as a token packet. For OUT and SETUP transactions, the address and endpoint fields uniquely identify the end

44、point that will receive the subsequent Data packet. For IN transactions, these fields uniquely identify which endpoint should transmit a Data packet. For PING transactions, these fi</p><p>　　Token packets ha

45、ve a five-bit CRC that covers the address and endpoint fields as shown above. The CRC does not cover the PID, which has its own check field. Token and SOF packets are delimited by an EOP after three bytes of packet field

46、 data. If a packet decodes as an otherwise valid token or SOF but does not terminate with an EOP after three bytes, it must be considered invalid and ignored by the receiver.</p><p>　　1.4.1 Start-of-Frame Pa

47、ckets</p><p>　　Start-of-Frame (SOF) packets are issued by the host at a nominal rate of once every 1.00 ms 0.0005 ms for,a full-speed bus and 125 μs 0.0625 μs for a high-speed bus. SOF packets consist of a P

48、ID indicating packet type followed by an 11-bit frame number field as illustrated in Figure 8-13. </p><p>　　The SOF token comprises the token-only transaction that distributes an SOF marker and accompanying

49、frame number at precisely timed intervals corresponding to the start of each frame. All high-speed and fullspeed functions, including hubs, receive the SOF packet. The SOF token does not cause any receiving function to g

50、enerate a return packet; therefore, SOF delivery to any given function cannot be guaranteed.</p><p>　　The SOF packet delivers two pieces of timing information. A function is informed that an SOF has occurred

51、 when it detects the SOF PID. Frame timing sensitive functions, that do not need to keep track of frame number (e.g., a full-speed operating hub), need only decode the SOF PID; they can ignore the frame number and its CR

52、C. If a function needs to track frame number, it must comprehend both the PID and the time stamp. Full-speed devices that have no particular need for bus timing information ma</p><p>　　1.4.2 Handshake Packet

53、s</p><p>　　Handshake packets are used to report the status of a data transaction and can return values indicating successful reception of data, command acceptance or rejection, flow control, and halt conditi

54、ons. Only transaction types that support flow control can return handshakes. Handshakes are always returned in the handshake phase of a transaction and may be returned, instead of data, in the data phase. Handshake packe

55、ts are delimited by an EOP after one byte of packet field. If a packet decodes as an</p><p>　　1.ACK indicates that the data packet was received without bit stuff or CRC errors over the data field and that th

56、e data PID was received correctly. ACK may be issued either when sequence bits match and the receiver can accept data or when sequence bits mismatch and the sender and receiver must resynchronize to each other. An ACK ha

57、ndshake is applicable only in transactions in which data has been transmitted and where a handshake is expected. ACK can be returned by the host for IN transactions an</p><p>　　2.NAK indicates that a functio

58、n was unable to accept data from the host (OUT) or that a function has no data to transmit to the host (IN). NAK can only be returned by functions in the data phase of IN transactions or the handshake phase of OUT or PIN

59、G transactions. The host can never issue NAK. NAK is used for flow control purposes to indicate that a function is temporarily unable to transmit or receive data, but will eventually be able to do so without need of host

60、 intervention.</p><p>　　3.STALL is returned by a function in response to an IN token or after the data phase of an OUT or in response to a PING transaction. STALL indicates that a function is unable to trans

61、mit or receive data, or that a control pipe request is not supported. The state of a function after returning a STALL (for any endpoint except the default endpoint) is undefined. The host is not permitted to return a STA

62、LL under any condition.</p><p>　　The STALL handshake is used by a device in one of two distinct occasions. The first case, known as “functional stall,” is when the Halt feature associated with the endpoint i

63、s set. A special case of the functional stall is the “commanded stall.” Once a function’s endpoint is halted, the function must continue returning STALL until the condition causing the halt has been cleared through host

64、intervention.</p><p>　　Protocol stall is unique to control pipes. Protocol stall differs from functional stall in meaning and duration. A protocol STALL is returned during the Data or Status stage of a contr

65、ol transfer, and the STALL condition terminates at the beginning of the next control transfer (Setup). The remainder of this section refers to the general case of a functional stall.</p><p>　　2 Transaction P

66、acket Sequences</p><p>　　The packets that comprise a transaction varies depending on the endpoint type. There are four endpoint types: bulk, control, interrupt, and isochronous.</p><p>　　Batch t

67、ransaction type were characterized by the error detection and retry way to ensure the host and function of data between the components of the ability to send error-free. Flow control and hang in some conditions, the data

68、 phase handshake signals are replaced, resulting in two with no data transfer phase of the transaction.</p><p>　　When the host is ready to receive a batch of data when it sends the input tag. Feature port th

69、rough the return packet, or if unable to return data, NAK, or STALL handshake is returned as a response. NAK means the feature is temporarily unable to return data, and STALL be stopped permanently, said the port needs t

70、o USB system software intervention. If the host receives a legitimate data packets, then it uses ACK handshake to answer. If you receive data with the host detects an error, then it does</p><p>　　Control of

71、transmission at least two transaction stages: the establishment and status. Transmission can be selectively controlled, including the establishment and status data between the stages of phase. In the establishment phase,

72、 the establishment of services for the features of the control port to transmit information. Establishment of issues in the format similar to the output, but the use of the building rather than the output of the PID. Bui

73、lding is always in the establishment of services </p><p>　　Control the data transmission phase, if any, by more than one input or output transaction structure, compliance and batch send the same protocol rul

74、es. All the data phase of the transaction must have the same direction (that is, all input or all output). In the data phase, the amount of data to be sent, and its direction is specified in the establishment phase. If t

75、he amount of data exceeds the previously identified data packet size, the data in support of the largest packet size of the number o</p><p>　　Control of the state of transmission phase is the last one operat

76、ion sequence. State phase at a relatively earlier stage of the data to characterize the changes in flow direction, and always use the DATA1 PID. For example, if the data phase transaction constituted by the output, the s

77、tate is a single input transaction. If the control sequence is no data transmission phase, then it is by the establishment phase and the subsequent transaction by the input stages, consisting of the state.</p><

78、;p>　　Interrupt transactions may consist of IN or OUT transfers. Upon receipt of an IN token, a function may return data, NAK, or STALL. If the endpoint has no new interrupt information to return (i.e., no interrupt is

79、 pending), the function returns a NAK handshake during the data phase. If the Halt feature is set for the interrupt endpoint, the function will return a STALL handshake. If an interrupt is pending, the function returns t

80、he interrupt information as a data packet. The host, in response to </p><p>　　When an endpoint is using the interrupt transfer mechanism for actual interrupt data, the data toggle protocol must be followed.

81、This allows the function to know that the data has been received by the host and the event condition may be cleared. This “guaranteed” delivery of events allows the function to only send the interrupt information until i

82、t has been received by the host rather than having to send the interrupt data every time the function is polled and until the USB System Software clear</p><p>　　3 Data Toggle Synchronization and Retry</p&

83、gt;<p>　　The USB provides a mechanism to guarantee data sequence synchronization between data transmitter and receiver across multiple transactions. This mechanism provides a means of guaranteeing that the handsha

84、ke phase of a transaction was interpreted correctly by both the transmitter and receiver. Synchronization is achieved via use of the DATA0 and DATA1 PIDs and separate data toggle sequence bits for the data transmitter an

85、d receiver. </p><p>　　Only in the receiver can receive data and with the correct data PID received error-free packet when the receiver sequence bit before switching. But only in the data transmitter to recei

86、ve a legitimate ACK handshake when the transmitter sequence bit before switching. Data transmitter and receiver must be synchronized in the transaction the beginning of the timing of their position. Synchronization mecha

87、nism used varies with the transaction type. ISO does not support data transmission switch synch</p><p>　　Control transfers use the SETUP token for initializing host and function sequence bits. Figure 8-44 sh

88、ows the host issuing a SETUP packet to a function followed by an OUT transaction. The numbers in the circles represent the transmitter and receiver sequence bits. The function must accept the data and return ACK. When th

89、e function accepts the transaction, it must set its sequence bit so that both the host’s and function’s sequence bits are equal to one at the end of the SETUP transaction.</p><p>　　If data cannot be accepted

90、 or the received data packet is corrupted, the receiver will issue a NAK or STALL handshake, or timeout, depending on the circumstances, and the receiver will not toggle its sequence bit. Any non-ACK handshake or timeout

91、 will generate similar retry behavior. The transmitter, having not received an ACK handshake, will not toggle its sequence bit. As a result, a failed data packet transaction leaves the transmitter’s and receiver’s sequen

92、ce bits synchronized and untoggled</p><p>　　The transmitter is the last and only agent to know for sure whether a transaction has been successful, due to its receiving an ACK handshake. A lost or corrupted A

93、CK handshake can lead to a temporary loss of synchronization between transmitter and receiver as shown in Figure 8-47. Here the transmitter issues a valid data packet, which is successfully acquired by the receiver; howe

94、ver, the ACK handshake is corrupted.</p><p>　　At the end of transaction i, there is a temporary loss of coherency between transmitter and receiver, as evidenced by the mismatch between their respective seque

95、nce bits. The receiver has received good data, but the transmitter does not know whether it has successfully sent data. On the next transaction, the transmitter will resend the previous data using the previous DATA0 PID.

96、 The receiver’s sequence bit and the data PID will not match, so the receiver knows that it has previously accepted thi</p><p>　　The data transmitter must guarantee that any retried data packet is identical

97、(same length and content) as that sent in the original transaction. If the data transmitter is unable, because of problems such as a buffer underrun condition, to transmit the identical amount of data as was in the origi

98、nal data packet, it must abortthe transaction by generating a bit stuffing violation for full-/low-speed. An error for high-speed must be forced by taking the currently calculated CRC and complementing </p><p&

99、gt;　　4 Error Detection and Recovery</p><p>　　The USB permits reliable end-to-end communication in the presence of errors on the physical signaling layer. This includes the ability to reliably detect the vast

100、 majority of possible errors and to recover from errors on a transaction-type basis. Control transactions, for example, require a high degree of data reliability; they support end-to-end data integrity using error detect

101、ion and retry. Isochronous transactions, by virtue of their bandwidth and latency requirements, do not permit retries </p><p>　　Neither the device nor the host will send an indication that a received packet

102、had an error. This absence of positive acknowledgement is considered to be the indication that there was an error. As a consequence of this method of error reporting, the host and USB function need to keep track of how m