USB Pinout

August 14, 2008

Since I have done a lot of writing in the past about USB devices, I often get questions about the actual USB hardware. One of the biggest questions that I get is about the USB pinout specifications. Just what are each of those pins and what do they do.

Well, the USB pinout varies, depending upon which type of USB plug and receptical you have.

Series A USB Pinout

This is usually what you see most USB devices such as mice and keyboards using. These are four pin devices, two pins for power (1,4) and two pins for data (2,3). The power pins transfer 5V DC.

Series B USB Pinout

These are more popular on USB hard drives, CD/DVD drives and scanners. Just like Series A, these are four pin devices, two pins for power (1,4) and two pins for data (2,3). The power pins transfer 5V DC.

Mini-USB Series A USB Pinout

The Mini-USB series went to a five pin design, even though one pin is either not used or is redundant. You will usually see these on cameras or other such devices. Pins 1 and 5 are for power and pins 2 and 3 provide data access. Pin 4 is connected to pin 5 for redundancy.

Mini-USB Series B USB Pinout

Just like Mini-USB Series A, Series B used five pins, two for power (1,5) and two for data (2,3). Pin 4 is not connected and serves no purpose.

Summary Tables

Standard USB Pinout & Cable Color Code

Pin Wire Color                     Function
1 Red                                    V BUS (5V)
2 White                                  Data-
3 Green                                  Data+
4 Black                                  Ground

Mini-USB Type-A Pinout & Cable Color Code

Pin Wire Color                   Function

1 Red                                    V BUS (5V)
2 White                                 Data-
3 Green                                 Data+
4 Joined to pin 5 ID
5 Black                                 Ground

Mini-USB Type-B Pinout & Cable Color Code

Pin Wire Color                 Function

1 Red                                 V BUS (5V)
2 White                              Data-
3 Green                              Data+
4 Not connected (*) ID
5 Black                              Ground

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