Short for Enhanced Host Controller Interface. The Enhanced Host Controller Interface (EHCI) specification describes the register-level interface for a Host Controller for the Universal Serial Bus (USB). The EHCI specification describes a host controller that correctly supports all compliant USB 2.0 low-, full-, and high-speed devices. It includes a description of the hardware/software interface between system software and the host controller hardware. This specification is intended for hardware component designers, system builders and device driver developers.