Embedded Hosts - USB Mass Storage: Designing and Programming Devices and Embedded Hosts - page 267

The chip has two host/device SIEs and four USB transceivers that allow the
device to have any of these configurations:
1 to 4 hosts
1 or 2 devices
1 host and 1 device
1 OTG device and one device-only function
1 OTG device and up to two additional hosts
In a mass-storage host application, the chip can be configured to function as
a mass-storage host, as an OTG device that can function as a mass-storage
host and device, or as a mass-storage host and device at the same time.
The development board also has an IDE interface that connects to a daugh-
ter board that can hold a small hard drive. With a drive attached, the devel-
opment board can function as a USB drive.
The kit includes a GNU C compiler, assembler, linker, debugger, a develop-
ment environment, and utilities. Example firmware supports FAT file sys-
tems and USB host communications with mass-storage devices.
Host Software
Several sources offer software for use in embedded systems functioning as
mass-storage hosts. Windows CE 5.0 includes a USB host mass-storage
driver. Linux includes mass-storage drivers and is suitable for some embed-
ded applications. Other sources offer USB host stacks for use with a variety
of embedded-system operating systems, host controllers, and CPU architec-
tures. Sources for host stacks with mass-storage support include Accelerated
Technology, Intoto, Jungo Ltd., Micro Digital, On Time Software, and
SoftConnex.
A Mass-storage Host Module
Another approach to designing an embedded host is the USBwiz TM chip
from GHI Electronics. This is the same company that offers the uALFAT
chip described in Chapter 8. The USBwiz is a Philips LPC2138 ARM pro-
cessor programmed to support FAT file systems and several USB device
classes, including mass storage. The chip interfaces to a Philips ISP1160
USB host controller chip.