Microsoft Technology Licensing, LLC

Eiko Junus

John Allen Tardif

Wei Guo

Harjit Singh

Ankur Varma

Mitchell Stephen Dernis

Gregory George Williams

Stephen Z Au

An extension to the Universal Serial Bus (USB) protocol that utilizes reserved bits in the OHCI Endpoint Descriptors to signal which root hub port(s) should transmit the data. Typically, all ports transmit (broadcast) data. The present invention encodes transmission information that can be used by the hardware to effectively control which port(s) need to be tri-stated. However, by setting, the 'on' bits for all the ports, the present invention retains standard USB functionality. Also provided is a method to increase the bandwidth of low speed devices connected to the USB bus by increasing the data payload for such devices.

Extended USB protocol with selective broadcast mechanism

A Multiple Input Shift Register (MISR) is used to generate signatures, based on data from a device under test, in order to validate the proper sequence and content of the data over a defined period of time. The MISR described herein includes the ability to 'tag' the signatures for each time period using an incrementing value, and make that tag and the signature readable by a test controller. The MISR has the flexibility to be reset to a known initial state (or otherwise load a seed value) at the beginning of each time period or to continue accumulating signatures without being reset (or using the seed value). Accumulation of signatures over an extended period of time allows a test controller to validate that no errors occurred during a long term test without having to closely monitor the intermediate results.

Digital signature generation for hardware functional test

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Eiko Junus