USB Accessories on Android Tablets
Probably the most common use of a USB port is connecting to a PC to transfer files between the PC and tablet. This link discusses that method in detail –> How to Connect a Tablet to a PC.
There are 3 types of USB ports available that can be used on a USB device. The difference between USB 1.0, 2.0, and 3.0 are significant:
- USB 1.0 - 12 Mbit/s, Does not support extension cables or USB hubs due to power limitations. There are not any devices that are using this USB type any longer.
- USB 2.0 – 480 Mbit/s (60 MB/s) High Speed (40 times faster than 1.0), also added support for battery charging and micro ports.
- USB 3.0 - 5 Gbit/s (625 MB/s) (10 times faster than 2.0), lower power consumption, backward compatible with USB 2.0 and 1.0.
Most tablet PCs being released today have USB 2.0 ports with a couple that have USB 3.0. While there are not many USB accessories using USB 3.0 yet, this would still be the preference for any tablet.
Android tablet PCs support a variety of USB devices in two modes, Host and Accessory. When a USB device is operating in Accessory mode, the device is acting as the Host. Examples of USB accessory devices include medical equipment, robotics controllers; docking stations; diagnostic devices; musical equipment; kiosks; card readers; etc.
USB devices running in Host mode include digital cameras, keyboards, mice, Pens, Bluetooth dongles, and game controllers. It is important to note that you must have Android 3.1 or greater in order to use a USB device in Host mode.
The degree of success you will have using a USB device will vary, meaning, some will work, some will not work. One might work on an Acer tablet, but not work on a Samsung tablet, and vice versa. The USB APIs are the same for all Android 3.1+ tablets, however, each manufacturer applies some customizations to the OS for their own tablets. Samsung’s TouchWiz OS overlay is an example of this.
In theory, you should be able to connect an USB keyboard, mouse, and storage device to a tablet PC. Which some readers have done with varying degrees of success. Also, be aware of the size of the USB connector, most tablets use a micro USB connector, which is not a common connector size for keyboard, mice, etc.
When you connect a keyboard to the USB slot, then open an app that uses a keyboard, instead of the on-screen keyboard automatically opening, you will see an icon on the notification bar which looks like a keyboard, which is indicating that the tablet recognizes that an external keyboard is attached. If you touch the keyboard icon, a dialog will open allowing you to select options for using the external keyboard.
Reports from various forums recommend using a USB hub with a connector that fits into your USB connector (use an adapter to make it fit). Then plug the USB devices into the hub. It also seems that a tablet will only read one storage device at a time. So plugging in a USB memory card and a camera will not work, be sure to remove your SD memory card before you connect a USB memory stick.
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