Mini-USB Connector pinout

USB (Universal Serial Bus) designed to connect peripherals and exist in a wide variety of digital devices.

Pin	Name	Cable color	Description
1	VCC	Red	+5 VDC
2	D-	White	Data -
3	D+	Green	Data +
X	ID		May be N/C, GND or used as an attached device presence indicator (shorted to GND with resistor)
4	GND	Black	Ground

USB pinout signals

USB is a serial bus. It uses 4 shielded wires: two for power (+5v & GND) and two for differential data signals (labelled as D+ and D- in pinout). NRZI (Non Return to Zero Invert) encoding scheme used to send data with a sync field to synchronise the host and receiver clocks. In USB data cable Data+ and Data- signals are transmitted on a twisted pair. No termination needed. Half-duplex differential signaling helps to combat the effects of electromagnetic noise on longer lines. Contrary to popular belief, D+ and D- operate together; they are not separate simplex connections.

USB cable wires:

Shielded:
Data: 28 AWG twisted
Power: 28 AWG - 20 AWG non-twisted
Non-shielded:
Data: 28 AWG non-twisted
Power: 28 AWG - 20 AWG non-twisted

Power Gauge	Max length
28	0.81 m
26	1.31 m
24	2.08 m
22	3.33 m
20	5.00 m