USB 2.0 Enhanced

SANTA CLARA, Calif., December 20, 2000
Intel Corporation has announced the first public release of its USB 2.0 Enhanced Host Controller Interface (EHCI) Specification. The spec standardizes the interface between the USB 2.0 host controller and its software driver. Intel is licensing the spec on a royalty-free basis to all interested parties. During the development of USB 1.0, the existence of two versions of host controller interface specs (UHCI and OHCI) made it more difficult for OS vendors to develop software support for multiple implementations of host controllers in the industry, according to Jason Ziller, Intel technology initiatives manager. For USB 2.0, Intel's goal was to develop one spec that the entire industry would use, increasing compatibility of the various implementations and making it easier to develop software support for all.

Intel developed the EHCI spec with contribution from NEC, Philips, Lucent, Microsoft and Compaq. The spec defines an architecture that is fully compatible with USB 1.1 and 2.0 devices and hubs. It can even run USB 1.1 devices with existing USB 1.1 software drivers. The architecture is also highly optimized, and therefore consumes minimum CPU overhead - less than the amount that a USB 1.1 UHCI host controller consumes. In addition, existing USB 1.1 devices connect to USB 1.1 "companion" controllers, and therefore leave all of the high-speed bandwidth for USB 2.0 high-speed devices.

Intel is developing compliance testing to complement the EHCI spec, which has so far been licensed to more than 25 companies. Compliance testing will be made available to the industry in order for vendors to demonstrate compliance to the spec. The initial test suite is expected to be released in the first half of next year.

This first public version of the EHCI spec is designated revision 0.95. This release enables production shipment of discrete USB 2.0 host controllers, such as ones already announced by NEC and Lucent. Final version of the EHCI spec is expected to be released next year after final validation tests are completed. The EHCI spec and license agreement can be found on Intel's website at developer.intel.com/technology/usb/.