Figure 2 shows how the Renesas UASP driver works together with the Renesas USB 3.0 Host Controller driver and other software elements in the complete software solution for supporting USB devices. The top-level application program interfaces with either the standard Mass Storage Class (MSC) driver in Windows, which operates in BOT mode, or with the new UASP driver, which bypasses the MSC driver and interfaces directly with the Renesas USB 3.0 Host Controller Drivers (Root Hub and xHCI). The UASP driver also interacts with the MSC driver in various ways as needed.

73593_fig2

Figure 2: Renesas’ UASP, Hub and xHCI software stack used with Microsoft Windows XP, Vista and Windows 7.

It should be noted that there is no public standard at present for the interface between the UASP driver and the USB 3.0 xHCI driver. The Renesas UASP driver is designed specifically to operate with the Renesas xHCI driver and other compatible xHCI drivers.