Method and apparatus for extending communications over USB
First Claim
1. A system for extension of communications between a USB host and a USB device over an extended distance, comprising:
- a USB-compliant near-end link coupled to the USB host;
a USB-compliant far-end link coupled to the USB device;
a near-end extender unit coupled to the near-end link; and
a non-USB communications channel connecting the near-end extender unit to a far-end extender unit to define a relay extension;
the near-end extender unit including means for translating communications received from the USB host from a USB-compliant reflective signal to a first terminated signal and means for transmitting the first terminated signal via the non-USB communications channel;
the far-end extender unit coupled to the far-end link and including means for translating communications received from the near end extender unit as the first terminated signal via the non-USB communications channel back to a USB-compliant reflective signal and relaying the USB-compliant reflective signal to the USB device.
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Abstract
Method and apparatus are described for improving information transfer over USB. In one approach, hub-based extension is realized wherein power is distributed using auxiliary wiring distinct from signal and power wiring present in conventional USB cabling. Additional signals allow optimization of power distribution for powering attached devices, and for detecting and handling illegal connection configurations. In another approach, improvements are realized through use of alternative signaling techniques which eschew reflective and high-speed common-mode signaling. Described are various configuration, media and signal-protocol combinations, including implementations containing embedded hubs. Methods ensuring reliable system behavior are also described, including determination of extension path delay and use of topology-enforcement hubs. In other approaches, further improvements are realized by allowing information exchanges to take longer than the nominal timeout period, or by allowing host requests to be delayed for transmission until the extended bus is available for use.
62 Citations
35 Claims
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1. A system for extension of communications between a USB host and a USB device over an extended distance, comprising:
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a USB-compliant near-end link coupled to the USB host;
a USB-compliant far-end link coupled to the USB device;
a near-end extender unit coupled to the near-end link; and
a non-USB communications channel connecting the near-end extender unit to a far-end extender unit to define a relay extension;
the near-end extender unit including means for translating communications received from the USB host from a USB-compliant reflective signal to a first terminated signal and means for transmitting the first terminated signal via the non-USB communications channel;
the far-end extender unit coupled to the far-end link and including means for translating communications received from the near end extender unit as the first terminated signal via the non-USB communications channel back to a USB-compliant reflective signal and relaying the USB-compliant reflective signal to the USB device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method for USB extension of a communications link between a USB host and a USB device signal over an extended distance, comprising:
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providing a non-USB communications channel between a USB-compliant near-end link coupled to the USB host and a USB-compliant far-end link coupled to the USB device to define a relay extension;
translating communications received from one of the USB host and USB device from a USB-compliant reflective signal to a terminated signal;
transmitting the terminated signal via the non-USB communications channel;
translating the terminated signal received via the non-USB communications channel back to a USB-compliant reflective signal; and
relaying the USB-compliant reflective signal to the other of the USB device and USB host. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. An extension-optimized, self-powered hub for use in a USB-compliant system, the hub comprising:
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USB hub circuitry;
an upstream USB connection;
a downstream USB connection; and
an auxiliary power connection. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35)
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Specification