If you’ve been wondering, “Who invented OTG?” then you’ve come to the right place. USB On-The-Go (OTG) is a USB specification that allows certain USB devices to take on the role of a host and connect to other USB devices. OTG also allows for these devices to swap roles, which makes them more flexible. For example, mobile phones can act as host devices when connected to a host computer. They can also present themselves as a USB Mass Storage Device (USB flash drive) when connected to another host computer.
The basic idea behind OTG is that OTG cables are USB connectors with micro-A and micro-B plugs at the ends. The fifth pin, known as the ID pin, is a key feature of an OTG device. The USB 2.0 Specification includes the current USB 1.1 specification, but also introduces a third speed. Therefore, your gadget should recognize an OTG device when connected to it. The following table describes the various types of OTG.
A USB OTG device is backward compatible with USB 2.0 and USB 3.0. This means that it will behave the same as a standard USB host when connected to a standard USB device. Typically, the OTG device requires a separate power source for TPL listed products. The powered USB hub can sidestep this problem because it provides power according to USB specifications. The device may also be backward compatible with older USB devices.
USB OTG introduced a new type of communication that allows two USB devices to interact without a PC. This new standard doesn’t add peer-to-peer connections, but instead introduces the dual-role device, which can act as both a host and a peripheral device. This device can exchange roles with any USB device, whether it’s a standard A mini-B. And, because the USB OTG connector can work with other USB devices, it’s easy to use OTG.
OTG was first used in mobile devices, such as iPods. The device is a standard “micro-B” plug, which features a floating ID pin. The mini-B device can automatically detect this pin and configure itself as an MTV, PTP, or mass storage. The A-Device can power down the VBUS wire, if necessary, and can detect when the B-Device has stopped functioning.
The basic OTG Vbus pulsing circuits are illustrated in FIG. 5. The transistor 604 is driven by the input 600, which is 3.3 volts. A resistor 603 limits the current drive from the 3.3-volt supply 610. The transistor charges the capacitor 605, which discharges through resistor 601 in series with resistor 602, and signals the B-Device to receive the SRP.