Mechanical and electronic standards
USB signals are transmitted using twisted pairs labeled D+ and D-, respectively, and they each use half-duplex differential signals and work together to counteract electromagnetic interference on long wires.
1. Standard USB connector contacts
|
Contacts
|
Function (host)
|
Function (device)
|
|---|---|---|
|
1
|
VBUS (4.75－5.25 V)
|
VBUS (4.4－5.25 V)
|
|
2
|
D-
|
D-
|
|
3
|
D+
|
D+
|
|
4
|
Grounding
|
Grounding
|
2. Mini USB connector contacts
Mini USB Interface In addition to the 4th pin, all other USB interface functions are the same as those of standard USB. The 4th needle becomes the ID, and it is connected to the 5th needle on the mini-A, and can also be connected to the 5th needle on the mini-B.
|
Contacts
|
Features
|
colour
|
|---|---|---|
|
1
|
VBUS (4.4–5.25 V)
|
red
|
|
2
|
D−
|
White
|
|
3
|
D+
|
green
|
|
4
|
ID
|
|
|
5
|
Grounding
|
black
|
3. Micro USB interface
|
Contacts
|
Features
|
colour
|
|---|---|---|
|
1
|
VBUS (4.4–5.25 V)
|
red
|
|
2
|
D−
|
white
|
|
3
|
D+
|
green
|
|
4
|
ID
|
|
|
5
|
Grounding
|
black
|
4. Micro-USB plug
On January 4, 2007, the USB-IF installed the Micro-USB plug standard. The standard will replace Mini-USB on many new smart phones and PDAs. The plug-in life of the Micro-USB plug is 10,000 times. Compared to Mini-USB plugs, its height is halved and its width is almost the same. The OMTP organization recently announced that Micro-USB will become the standard interface for mobile device data and power.
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Post time: Apr-11-2018