USB Time Synchronization via Distributed Local Timebases
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Solution Overview
Problem
Existing integrated circuits face challenges in synchronizing local timebases with a global timebase across multiple components, particularly in systems like USB devices where precise time alignment is crucial for event synchronization.
Innovation Solution
The proposed solution involves a distributed timebase circuit that provides multiple local timebases synchronized to a global timebase, along with a Time Synchronization Circuit (TSC) that captures timestamps based on both the global and local timebases, ensuring consistent time measurement across the apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single global timebase is used across all components, then time consistency is improved, but device complexity increases due to the need for distribution and synchronization infrastructure
Solution Approach 1:
The system divides the timebase functionality into multiple distributed local timebases, each maintained by individual components, rather than using a single centralized timebase. This segmentation allows each component to have its own time reference while still achieving overall synchronization through the TSC's timestamp correlation mechanism.
Solution Approach 2:
The Time Synchronization Circuit (TSC) acts as an intermediary that captures and correlates timestamps from multiple local timebases with the global timebase. This intermediary component enables time consistency across distributed components without requiring direct complex interconnections between all components.
2Device complexity
If multiple local timebases are distributed across components, then device complexity is reduced, but time synchronization precision deteriorates due to drift and lack of coordination
Solution Approach 1:
The TSC continuously captures timestamps from local timebases and the global timebase, creating a feedback mechanism that monitors time drift. This feedback enables detection and correction of synchronization deviations, maintaining time precision despite the distributed nature of the timebases.
Solution Approach 2:
The system performs preliminary timestamp capture and correlation through the TSC before time drift becomes significant. By continuously recording timestamps at defined interface points, the system proactively maintains synchronization accuracy rather than reacting to drift after it occurs.
3Ease of operation
If timestamps are captured at interface points, then ease of operation is improved, but measurement precision may be affected by interface processing delays
Solution Approach 1:
The TSC automatically captures timestamps at defined interface points without requiring manual intervention or complex external synchronization procedures. This self-service approach simplifies operation while maintaining precision by using the interface's own timing signals (such as SOF packets) as reference points.
Data Source
AI summary
An apparatus includes components, a distributed timebase circuit, an interface and a Time Synchronization Circuit (TSC). The timebase circuit is configured to provide local timebases in physical proximity to the components, and synchronize the local timebases to a global timebase so as to provide a consistent time measurement. The interface is configured to be coupled to one or more devices. Transmissions on the interface are logically divided into a plurality of frames. Time on the interface is defined based on a frame number identifying a particular frame. The TSC is configured to capture a first timestamp based on the frame number corresponding to a point in time on the interface, and to concurrently capture a second timestamp based on a local timebase corresponding to the point in time, wherein the first timestamp and the second timestamp correlate time on the interface to the consistent time measurement.