Mechanics of USB cable and connector

給出了當前有且僅有的四種USB PLUG（所謂的公頭）。

對於Standard系列，1-4腳如下定義

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Contact Number 觸點號碼      Signal Name訊號名    Typical wiring Assignment
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1                                              VBUS                                  Red
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2                                             
D-                                       White
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3                                              D+                                      Green
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4                                             
GND                                   Black
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Shell外殼                                  Shield屏蔽                    Drain Wire排擾線
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對於Mini系列，1-5腳如下定義

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Contact Number                      Signal Name           Typical Wiring Assignment
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1                                             VBUS                                  Red
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2                                               D-                                     White
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3                                               D+                                    Green
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4                                               ID                             A:To GND | B: Float
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5                                               GND                                 Black
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Shell                                         Shield                            Drain Wire
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Standard A是最常見的，USB滑鼠鍵盤，多數隨身碟的接頭都是該類型，可以直接插入PC上的Standard A Receptacle（母頭）。Standard A的最大好處就是可以直接連到PC上不需要另外的USB連接線。

Standard B常見於比較“大型”的USB裝置上，比如印表機，掃描器等。

Mini系列和Standard的最大區別在於Standard系列只有4根線，而Mini系列有5根線，多了一根ID線，供OTG功能使用。Mini系列塊頭比較小，多見於小型USB手持功能，如MP3，PDA，手機等等。

Mini-
A規定接頭的塑膠部分為橢圓型，中間的USB標誌圖案也使用橢圓型括起來，最重要的是得把ID線接地了，如果要接電阻的話，阻抗必須<10歐。而
Mini-B則是ID線懸空或通過>100千歐的電阻接地，另外，規定Mini-B的塑膠部分應為矩形，USB
LOGO也用矩形括住。實際上用電阻的話必然增加USB線的成本，所以一般就是直接接地或者懸空了。