USB Signaling via Intermediate Transport Modules
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Solution Overview
Problem
USB signaling technologies face limitations in flexibility, particularly with regards to maximum cable length and transaction delays, which are challenging in environments requiring extended isochronous data links.
Innovation Solution
A system with first and second modules that anchor the host-side and device-side ends of an intermediate transport link, detecting isochronous endpoint activation and autonomously generating data requests to buffer and forward isochronous data, while blocking host requests until data is available, thereby extending USB signaling distances without violating USB timing specifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If USB cable length is extended beyond 5 meters, then the signaling distance is improved, but USB timing violations occur
Solution Approach 1:
The patent introduces an intermediate transport link with first and second modules that act as mediators between the USB host and device. These modules convert USB signals to intermediate transport signals, enabling extended distance communication while maintaining USB timing compliance through autonomous data request generation and buffering mechanisms.
Solution Approach 2:
The patent segments the USB communication path into multiple components: USB host, first module (host-side), intermediate transport link, second module (device-side), and USB device. This segmentation allows each component to be optimized independently, with the intermediate modules handling timing and buffering to enable extended cable lengths without violating USB timing specifications.
2Length of stationary object
If intermediate transport link is introduced, then cable length limitation is overcome, but device complexity increases
Solution Approach 1:
The first and second modules perform multiple functions: signal conversion between USB and intermediate transport protocols, autonomous data request generation, data buffering, and timing management. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in system complexity while enabling extended signaling distances.
3Reliability
If autonomous data request generation is implemented, then timing violations are avoided, but automation extent increases
Solution Approach 1:
The second module monitors USB signals to detect isochronous endpoint activation and uses this feedback to autonomously generate appropriately-timed data requests. The first module buffers incoming data and provides it to the host in response to host data requests, while blocking host requests from propagating to the device until forwarded data is available. This feedback mechanism ensures USB timing compliance while managing automation.
Data Source
AI summary
According to one aspect of the teachings herein, a system includes first and second modules that respectively anchor host-side and device-side ends of an intermediate transport link that interconnects a USB host to a USB device. The system detects when the host activates an isochronous endpoint in the device for an isochronous IN data transaction, and the second module autonomously generates data requests for the device and forwards the isochronous data output from the device towards the first module. In turn, the first module buffers the data and provides it to the host in response to host's data requests. However, the first module blocks host requests from propagating to the device and it NACKs host requests until forwarded data is available from the second module. Such operation remains transparent to the host and device, while avoiding USB timing violations, even for extended intermediate transport links.