HID Hides

This chapter describes the Human Input Device (HID) model, a standard way of interacting with user input devices. A HID device uses various descriptors to define its capabilities. A Report descriptor details the input reports that it can generate and the output reports it can receive. The next chapter describes how to write Windows client device drivers and user mode applications that can talk to HID devices.

The HID specification is an abstract model for most types of input device that people will use to control their computers. An input device can be a plain old keyboard, for example, a vehicle simulation rudder, or the soft on/off button for the computer.

The HID specification was written originally for USB devices and closely follows the USB descriptor model. However, it is sufficiently generic for HID to be used with other types of device.

Naturally, most of the time a HID device provides input data to the computer. However, you can output to a HID device (e.g., to turn on the NumLock LED on a keyboard). You can also control a feature of the device, such as the font used on a display device or an LED color.

In Windows, the system HID class driver provides an abstract view of the input device. The HID device itself can be a USB device, a IEEE 1394 device or even a plain PC-compatible device, provided an appropriate HID minidriver is written to interface to the bus or device.

In...