USB On-The-Go

If implementing standard USB, devices must assume one role or the other, with computers generally set up as hosts, while (for example) printers normally function as a Peripheral.

In the absence of USB OTG, cell phones often implemented Peripheral functionality to allow easy transfer of data to and from computers.

The host controls all data transfers over the bus, with the devices capable only of signalling (when polled) that they require attention.

[citation needed] USB OTG recognizes that a device can perform both Host and Peripheral roles, and so subtly changes the terminology.

The choice between host and peripheral roles is handled entirely by which end of the cable the device is connected to.

[citation needed] After initial startup, setup for the bus operates as it does with the normal USB standard, with the A-device setting up the B-device and managing all communications.

Role swapping does not work through a standard hub, as one device will act as a host and the other as a peripheral until they are disconnected.

[3] The latest version of the supplement also defines behavior for an Embedded Host which has targeted abilities and the same USB Standard-A port used by PCs.

A "traditional" approach includes four controllers, resulting in more gates to test and debug: Also, most gadgets must be either a host or a device.

Pure mini-A receptacles also exist, used where a compact host port is needed, but OTG is not supported.

Micro-A adapters allow for connection to standard-A plugs, as used on fixed or standard devices.

[7] These three states are used in the cases of: USB 3.0 introduced a backwards compatible SuperSpeed extension of the micro-AB receptacle and micro-A and micro-B plugs.

The adapter enables any standard USB peripheral to be attached to an OTG device.

[9] Samsung[10][11] Android version 3.1 or newer supports USB OTG, but not on all devices.

[12][13] Specifications listed on technology web sites (such as GSMArena, PDAdb.net, PhoneScoop, and others) can help determine compatibility.

Using GSMArena as an example, one would locate the page for a given device, and examine the verbiage under Specifications → Comms → USB.