This is the
configuration descriptor of the mouse we are examining. The analyser
is showing the significance of the 9 bytes which comprise the descriptor.
The first two
bytes show the length and descriptor type, as with any descriptor.
This is followed by a word which gives the total number of bytes
contained in the configuration descriptor collection. In this case
the four descriptors included contain a total of 34 bytes.
shows the number of interfaces in this device. Each interface could
represent a different function such as a keyboard function or an
audio transfer function. In this case though, we have a single interface
which we will see acts as a HID mouse function.
has a value of 1. This is the number which the Set Configuration
command must use to select this, the only, configuration.
has the value 0 to tell the host that this configuration has no
special string defined to describe it.
tells the host that the device is bus-powered, and supports the
remote wake-up functionality.
tells the host that the device will draw no more that one unit load,
or 100mA in normal operation.
In our current
mouse descriptor collection, the configuration descriptor is followed
by the (one and only) interface descriptor.