Overview

This chapter introduces the Universal Serial Bus (USB) by giving an overview of the technology, its low-level structure, and its device framework. The next chapter looks at how to write Windows device drivers using the USB Device Interface (USBDI). This chapter takes a brief look at the available classes of USB device that have common characteristics. The subsequent chapters look in detail at one of these classes for Human Input Devices (HID) ^[1].

The Universal Serial Bus (USB) is the recommended way to connect new low-speed or medium-speed external devices to PCs. It is simple for users to plug in a new USB device or remove one, even if the PC is switched on. The system configures itself automatically to accommodate the new device, prompting for the necessary driver.

The USB Specification defines all the basic physical, electrical, and logical characteristics of all USB systems. The Windows system drivers define the closely related USB Driver Interface (USBDI) for use by USB client device drivers. This chapter and the next look at both these USB models.

The USB specifications are available from the USB website at http://www.usb.org/developers/ in PDF format. I recommend that you also get the USB Compatibility Test software, usbcomp.exe. This includes the USBCheck tool to check whether a USB device meets some of the higher-level specifications. It also contains the HIDView program to inspect and test HID devices. The "Ignore hubs (Memphis only)" box should be checked for Windows 98. The Windows 2000...