UFSx Firmw.: UFS USB V2.8 (c) SarasSoft 2007.
Features This device allows a host (or an Operating System) to connect a device. Any device can be connected to a USB host controller. Such a controller may be part of a computer, such as its on-board motherboard, or a USB host controller chip that is included in a device, such as a USB mass storage device. A USB host controller implements the USB protocol, and provides the facilities to attach a device to a computer, to configure and manage the device, and to manage the data transfer to and from the device. Host Controllers The USB host controller is the most critical part of the USB device. This is the software component that handles the communications with the USB device. As the name indicates, the USB host controller implements the USB protocol. The USB host controller serves as an interface between the USB device and the computer. The USB host controller is connected to both the host bus and the peripheral bus. When a USB device is inserted into a computer, the host controller assigns it an address, assigns it a configuration, and provides power to it. Data Transfer In addition to connecting the host and the device, the USB host controller manages the data transfer between the two. This transfer is not a serial data transfer, but is accomplished via a parallel data path called a pipe. The USB host controller supports a number of data transfer protocols. As mentioned, these protocols include: the bulk transfer protocol, the interrupt transfer protocol, and the isochronous transfer protocol. The host controller may select one or more of these protocols for the data transfer between the host and the device. Pipes The pipes are used to transfer the data from the host to the device and from the device to the host. There are five types of pipes: control, bulk, interrupt, isochronous, and standard. Control pipes are used for configuration and status information. Bulk pipes are used for data. The remaining pipes are used to transfer interrupts and isochronous data. The number of pipes available for data transfer depends on the protocol that is used by the USB host controller. For example, the host controller may support two control pipes and twelve bulk pipes. The host controller may support two control pipes and four bulk pipes for the Interrupt Transfer protocol. For the Isochronous Transfer protocol, the host controller may support a maximum of four pipes. Device assignment The USB device is assigned an address, an interface, and a configuration by the USB host controller.