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.
| Pin | Name | Cable color | Description |
|---|---|---|---|
| 1 | VCC | Red | +5 VDC |
| 2 | D- | White | Data - |
| 3 | D+ | Green | Data + |
| 4 | ID | may be Dark Blue | Mode Detect. May be N/C, GND or used as an attached device presence indicator (shorted to GND with resistor) |
| 5 | GND | Black | Ground |
micro USB pinout signals
USB is a serial bus. Micro-USB cable uses 4 shielded wires: two for power (+5v & GND), 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. See also newer Micro-USB 3.0 cable pinout.
Micro-USB connectors
Micro-USB connectors, which were announced in 2007 have a similar width to Mini-USB, but approximately half the thickness, enabling their integration into thinner portable devices. There are two variants of plugs: Micro-A connector and Micro-B connector and two variants of receptacles - Micro-AB (for both Micro-A and Micro-B connectors) and Micro-B.
The device with the 5-pin connector has a pullup to high on the connector. Low (small value resistor to ground or connection to ground) if you are connecting an accessory that the device must ask as a host for. Additional Pseudo-standards added by some device manufacturers: If there is no-connect on the data pins, the device will assume it is connected to a charging only cable. Most devices can receive power in host mode, even though this is not part of the standard.
Power Delivered by Micro-USB 2.0 must not exceed 3A / 20 V (60 W), usually 2A/5V charger is used.
USB On-The-Go
USB On-The-Go (OTG) introduces the concept of a device performing both master and slave roles. It Allows portable devices (such as cell phones which support OTG) to connect directly to other devices such as USB keyboards, mice and mass-storage devices.All current OTG devices are required to have Micro-AB receptacle usb connector usually marked as 'host aor some symbol.
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