USB On-The-Go logo
USB On-The-Go , often abbreviated to USB
OTG or just OTG, is a specification first
used in late 2001 that allows USB devices
such as digital audio players or mobile
phones to act as a host, allowing other
USB devices such as USB flash drives ,
digital cameras , mice or keyboards to be
attached to them. Use of USB On-The-Go
allows those devices to switch back and
forth between the roles of host and client
devices. For instance, a mobile phone
may read from removable media as the
host device, but present itself as a USB
Mass Storage Device when connected to
a host computer.
In other words, USB On-The-Go
introduces the concept of a device
performing both master and slave roles –
whenever two USB devices are
connected and one of them is a USB On-
The-Go device, they establish a
communication link . The device
controlling the link is called the master
or host, while the other is called the
slave or peripheral.