Half-duplex differential signaling helps to combat the effects of electromagnetic noise on longer lines.
In USB data cable Data+ and Data- signals are transmitted on a twisted pair. NRZI (Non Return to Zero Invert) encoding scheme used to send data with a sync field to synchronise the host and receiver clocks.
Micro-USB cable uses 4 shielded wires: two for power (+5v & GND), two for differential data signals (labelled as D+ and D- in pinout). May be N/C, GND or used as an attached device presence indicator (shorted to GND with resistor) The micro-USB connector is often used for portable devices charging (with micro-usb charging cable) or mobile devices data transfer (with micro-usb data cable). Nowdays Micro-USB competes with newer USB type C and Micro-USB 3.0.
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