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A tiny change makes a big difference

Typically, USB works on a host/client basis (also known as master/slave). This means the host device - let's say a PC - is in control of the peripherals (clients) connected to it. It has the drivers and the software to understand the peripherals and access their data.

That's why when you connect your Android device to your computer, it is detected as a 'mass storage device' in the same way a USB stick or portable hard drive would be. This also explains why you can't connect two peripheral devices together - one has to be a host.

The unused SENSE pin is shorted to GND in USB OTG cables.

USB On-The-Go is different. With a tiny wiring change in the cable, your Android device (which is usually a client) can act as a host, allowing you to attach a wide variety of peripherals directly to your Android and access them the same way a laptop or PC would!

This requires a special USB OTG cable or adapter, and an Android smartphone which is OTG compatible. While there is no physical difference you can see with an OTG cable or adapter, be sure to look out for a USB product which clearly states On-The-Go or OTG support if this function is required.

What devices are OTG compatible?

The following list of OTG compatible devices has been farmed from the internet, and may not be 100% accurate or complete. For the final word on whether or not your device is OTG compatible, check your product packaging or user manual for the USB OTG logo, or simply do a search online of your devices' model number and the keyword 'OTG'.

What devices can you use with USB OTG?

• Keyboards and Mice - Most USB keyboards and mice can be attached via OTG and work splendidly on Android. Don't expect support for multimedia keys or macros, but for pointing, clicking and typing, it's great.
• Game Controllers -We know for sure that Wired Xbox 360 and PS3 controllers work, and its possible that others do, too. Not all games support controllers, but with a little set-up and maybe a third-party app, you can play games on your Android just like you do on your console.
• USB Sticks & Memory Cards - Regular USB-based flash drives and memory card adapters work great with OTG. This makes it easy to transfer files without needing a PC, which is great when away from home.
• Portable Hard Drives - Portable HDDs which have their own external power supply can work just like USB memory sticks, but if your portable HDD needs power from USB, it probably won't get enough juice from your Android to operate.
• USB Hubs - Yes! You can plug in basic USB hubs to connect multiple devices at once, like a keyboard, mouse and game controller at the same time. Not such a good idea if you want to attach and copy between multiple USB sticks, though.
• Cameras - DSLRs and Point-and-Shoot cameras which can transfer files via USB can also work just like a USB stick (or any other 'mass storage device').
• Other Phones - Sure! You can totally connect another phone to your OTG host and access its files - it's just like a big, smart USB stick.
• Ethernet Adapters - Some basic Network Adapters can work with OTG, providing fast wired network or internet access via Rj45 cable. A life-safer when the WiFi goes down or your hotel is stuck in 2006.
• Wireless Dongles - This is a bit hit and miss. Some dongles (eg: Xbox 360 Wireless Controller Receivers) can work with a third-party app installed, and others can also be made to operate, but the rule of thumb is that these won't be as reliable as their wired alternatives.
• Musical Instruments - Things like MIDI keyboards can be compatible with OTG with the right app installed.
• Digital Drawing Tablets - Digital Pens, Art Tablets and other devices which control a mouse pointer can also be OTG compatible so long as they don't need special drivers.
• Web Cameras - Some web cams can be used via a third-party app called SimpleWebCam, which at time of writing was not on the Play store and is only available from the authors website.

In theory, most devices which are HID compliant (Human Interface Device) should work great with Android and USB OTG, as well as any device which can work as a 'mass storage device' like Mp3 players and memory card readers. For more exotic peripherals like printers and scanners, the odds of them working are infinitesimally small because Android doesn't have the specialised drivers to communicate with them.

Need and OTG adapter cable?

We have OTG adapters for USB 2.0, USB 3.0 and USB 3.1 Type-C devices:

USB 2.0
OTG Adapter

USB 3.0
OTG Adapter

USB 3.1
Type-C OTG
Adapter

Lost when On-The-Go?

USB OTG can be a bit tricky and varies from devices to device. If you have any questions or corrections, please contact us - the more info we have the better!