In-system Design, Inc.

Eric J Luttmann

David C Gilbert

David D Luke

Ronald J Richter

A Universal Serial Bus (USB) peripheral bridge and method for operation are disclosed. The bridge simulates a device disconnect condition to its upstream USB hub or host, even though it remains connected and powered, when its associated peripheral is not ready to communicate, powered off, or physically disconnected. For an IEEE-1284-1994 peripheral connection, the bridge senses the condition of the PLH peripheral line. If the PLH line is deasserted or floating, the bridge simulates a device disconnect condition by either allowing its upstream hub or host to take the D&plus; data line low, or taking the line low itself. By not allowing itself to be enumerated on the USB unless its associated peripheral is ready, the bridge avoids confusion at the host and wasted bus resources. At the same time, the bridge may remain physically connected to the host regardless of the state of the peripheral, even if the bridge is powered from the host.

Universal serial bus peripheral bridge simulates a device disconnect condition to a host when the device is in a not-ready condition to avoid wasting bus resources

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Boise, ID, United States of America

Eric J Luttmann