USB Extension Device Managing Bus Event Timing
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Solution Overview
Problem
Current USB technologies are limited to a maximum distance of 5 meters between a host and a USB device, restricting the physical range of USB devices due to signal propagation delays, which hinders the efficient propagation of USB bus events over longer distances.
Innovation Solution
A system comprising an upstream facing port connected to a host via a USB connection and a downstream facing port connected to a USB device, capable of establishing a communication link over a non-USB communication link, allowing for the extension of USB events and maintaining bus state control by prolonging signals associated with bus resets and resumes until completion notifications are received.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If USB communication is extended beyond 5 meters, then the physical range of USB devices is improved, but signal propagation delays cause timing guideline violations
Solution Approach 1:
The patent introduces an intermediary device (USB extension device or hub) that acts as a mediator between the host and the USB device. This intermediary receives timing-critical signals from the host, processes them locally, and generates appropriate extended timing signals for the downstream USB device, thereby decoupling the timing requirements from the physical distance.
Solution Approach 2:
The patent segments the USB communication system into multiple sections with intermediate devices that can independently manage timing. By dividing the long cable connection into shorter segments with active intermediaries, each segment can maintain proper timing while the overall system achieves extended range.
2Productivity
If the response time window is reduced to ensure bandwidth efficiency, then bandwidth utilization is improved, but the physical range is limited
Solution Approach 1:
The intermediary device maintains the strict timing windows required for bandwidth efficiency while enabling extended cable lengths. It receives requests within the standard timing window from the host and manages the extended communication path to ensure responses are delivered within the required time frame, thus preserving bandwidth utilization despite increased distance.
3Loss of time
If signal propagation speed is increased, then the response time is reduced, but the physical distance that can be covered at a given time is extended
Solution Approach 1:
The intermediary device compensates for signal propagation delays by actively managing the timing of signals over extended distances. It receives signals from the host, processes them with appropriate timing adjustments, and forwards them to the USB device, ensuring that response times meet specifications regardless of cable length.
Data Source
AI summary
Methods and apparatus for implementing a port management protocol which can be used to manage communication between one or more USB devices and a USB host at a distance greater than that allowed by the USB Specifications are provided. In one aspect, a method for prolonging a bus event of a USB device at least until a notification is received that a corresponding bus event has been completed by the USB host is provided; and subsequently exchanging bus traffic between the USB host and USB device upon completion of the bus event by both devices.