USB Host Shield

The Arduino USB Host Shield is designed based on the MAX3421E used to connect a USB device to your Arduino board. MAX3421E is a USB peripheral/host controller containing digital logic and analogue circuitry. This is necessary to implement a full-speed USB peripheral or a full-/low-speed host compliant to USB specification rev 2.0. The shield supports the following device classes:

• HID devices: keyboards, mice, joysticks, etc.
• Support Game controllers like Sony PS3, Nintendo Wii, Xbox360.
• USB to serial converters: FTDI, PL-2303, ACM, as well as certain cell phones and GPS receivers.
• ADK-capable Android phones and tablets.
• Support Digital cameras like Canon EOS, Powershot, Nikon DSLRs, and P&S, as well as generic PTP.
• Mass storage devices like USB sticks, memory card readers, external hard drives, etc.
• Bluetooth dongles.

Arduino communicates with the MAX3421E via the SPI bus through the ICSP header. In digital pins 10, 11, 12, and 13 on the Uno and pins 10, 50, 51, and 52 on the Mega. On both boards, pin 10 is used to select the MAX3421E. Pins 7, 8, and 9 are used for GPX, INT, and RES pins.

The UNO USB shield for Arduino operates with standard (dual 5/3.3V) and 3.3V boards. This USB shield host complies with USB Specification Revision 2.0 (Full-Speed 12Mbps Peripheral, Full-/Low-Speed 12Mbps/1.5Mbps Host). Moreover, this shield is compatible with Mass storage devices, such as USB sticks, memory card readers, external hard drives (FAT32 Type File System – Mega Arduino only).o types of devices.

The Host device (server) in the shield controls the peripheral device(client
) and also provides power to it. Soon after the Arduino USB HOST function is established, it communicates with other USB devices and supports the USB HUB function. When a  USB device like a mouse or a keyboard is connected to your computer, the computer acts as the host and controls (or polls) the client device (keyboard or mouse or even an Arduino).