USB Info: Frequently Asked Questions

USB On-The-Go

Q1: Why has USB OTG been developed?
A1: Portable computing devices such as hand-helds, cell phones and digital cameras that today connect to the PC as a USB peripheral will benefit from having additional capability to connect to other USB devices. USB OTG defines a dual-role device, which can act as either a host or peripheral, and can connect to either a PC or other portable devices through the same connector.

Q2: Do both portable devices have to be dual-role in order for both devices on order to connect and operate?
A2: No, dual-role devices will connect to all PCs, and will also have host functionality to connect to supported USB peripherals.

Q3: Does USB OTG eliminate the need for a PC?
A3: No. In fact, USB OTG complements the concept of the "Extended PC", where the PC is at the center of the consumer's extended world of digital devices. By enabling basic functions between digital devices, USB OTG augments the capability of these PC peripherals, making them more valuable to consumers and corporate users.

Q4: Will USB OTG devices connect to the PC? Will they connect to any other USB peripheral?
A4: Yes, USB OTG devices will connect to PCs, as they are 100% compliant to the USB 2.0 specification. They will also have limited host capability that allows them to connect to a targeted set of other USB peripherals.

Q5: How does USB OTG compare with Bluetooth? Does it compete with it?
A5: USB OTG does not compete directly with Bluetooth. USB OTG allows devices to connect to many of the 1 billion supported USB devices, which have been shipping for over 5 years, while Bluetooth is just now shipping. USB OTG is much faster and cheaper than Bluetooth. However, USB OTG is expected to co-exist with Bluetooth on some portable devices such as hand-helds and cell phones, just as USB does today.

Q6: How does USB OTG compare with 1394? Does it compete with it?
A6: Since USB On-The-Go is targeted toward existing USB peripherals, it continues to differ in application focus with 1394, just as USB does today.

Q7: What happens when you plug two USB OTG dual-role devices together?
A7: When two dual role devices get connected together via a cable, the cable sets a default host and default peripheral. If the application is such that the roles need to be reversed, then the Host Negotiation Protocol (HNP) will provide a handshake that performs that function. This reversal will be completely invisible to the user.

Q8: Where can I find out more?
A8: The specification and more information on USB OTG can be found on the USB-IF website's OTG Developer's page at www.usb.org/developers/onthego/.

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