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USB Complete fourth- P45:This book focuses on Windows programming for PCs, but other computers and operating systems also have USB support, including Linux and Apple Computer’s Macintosh. Some real-time kernels also support USB. | Chapter 17 Accompanying each question is a reference to a section in the USB specification with more information. Device Framework The Device Framework tests verify that a device responds correctly to standard control requests. The USB Command Verifier USBCV software utility performs the tests. The USB Command Verifier Compliance Test Specification describes the tests. The USBCV software and test-specification document are available from the USB-IF s website. The USBCV software requires a PC with a USB 2.0 host controller. In addition any low- or full-speed devices being tested must connect to the host via an external USB 2.0 hub. When you run USBCV the software replaces the host-controller s driver with its own test-stack driver. On exiting USBCV the software restores the original driver. The USB-IF recommends running the software only on hosts that are using Microsoft s USB drivers. You can run the tests while using a USB mouse and keyboard or you can use a PS 2 mouse and keyboard if the system supports them. Before running USBCV create a Windows restore point so you can return to your previous system configuration if something goes wrong with the stack switch. The software has test suites for Chapter 9 Current Measurement HID Hub and OTG. In the Chapter 9 tests the host issues the standard control requests defined in Chapter 9 of the USB 2.0 specification and performs additional checks on the information returned by a device Figure 17-5 . For example on retrieving a device descriptor the software checks to see that the bMaxPacketSize0 value is valid for the device s speed and that the bDeviceClass value is either a value for a standard class or FFh vendor-defined . The software requests the device descriptor when the device is in the default address and configured states at both full and high speeds if the device supports both and in every supported configuration. The Chapter 9 tests also include these Enumerate the device multiple times with different .
