Configuration descriptor

The configuration descriptor describes one of the device configurations to the host. The descriptor contains the following information about a particular configuration:

• the total length of the configuration: this is the number of bytes required to transfer this configuration descriptor and the interface and endpoint descriptors associated to it
• its number of interfaces – must be >= 1
• its configuration value – this is not an index and can be any non-zero value
• whether the configuration is self-powered
• whether the configuration supports remote wakeup
• its maximum power consumption

The full format of the configuration descriptor is specified in section 9.6.3, Configuration, of the USB specification.