Multi-Matrix Bus Arbitration Priority Propagation
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Solution Overview
Problem
Existing microcontroller bus systems face instability and performance issues due to inconsistent arbitration schemes, congestion, and the need for complex protocols and oversized queues, especially in systems with no native quality of service support, leading to blocked high-priority requests and reduced system-wide efficiency.
Innovation Solution
A multi-matrix bus system that proactively propagates the highest priority request from an upstream arbitration node, ensuring each downstream node recognizes the highest priority request, using a single priority coding scheme to guarantee priority consideration across the network, thereby maintaining a consistent and reactive arbitration scheme without complex protocols or oversized queues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bus slaves are provided with large queues to store transfer requests, then network congestion is reduced and high-priority requests are not ignored, but area is wasted and queue management complexity increases
Solution Approach 1:
The patent applies preliminary action by proactively propagating priority information upstream before congestion occurs. Instead of waiting for queues to fill up and then backlogging requests, the system预先 (in advance) identifies high-priority requests and propagates their priority values upstream through the bus matrix, enabling early arbitration decisions that prevent queue overflow and eliminate the need for large slave queues.
Solution Approach 2:
The patent implements feedback by creating a closed-loop priority propagation mechanism. Priority values are propagated upstream and arbitration decisions are made based on this feedback information. The system continuously monitors and adjusts arbitration based on real-time priority information flowing through the bus matrix, enabling dynamic response to changing traffic conditions without requiring oversized queues.
2Speed
If local arbitration is used at each bus node, then arbitration decisions are made quickly at each node, but system-wide arbitration consistency is lost and high-priority requests may be blocked
Solution Approach 1:
The patent merges local arbitration capabilities with system-wide priority awareness by combining distributed arbitration nodes with centralized priority propagation. Each local arbitration node maintains its fast decision-making capability while simultaneously receiving and processing propagated priority information from upstream, effectively merging local speed with global consistency in a single unified arbitration system.
Solution Approach 2:
The patent makes each arbitration node universal by enabling it to perform both local arbitration functions and system-wide priority propagation functions. The arbitration nodes are designed to handle multiple roles: making local arbitration decisions, propagating priority information upstream, and responding to propagated priority values, thereby achieving both speed and consistency through multi-functionality.
3Area of stationary object
If bus protocols with strong ordering constraints are used, then bus area and latency are reduced, but quality of service support is lost and stability problems occur
Solution Approach 1:
The patent segments the arbitration function from the bus protocol itself. Instead of embedding quality of service support directly in the strongly-ordered bus protocol, the patent separates priority propagation and arbitration logic into distinct modules that operate on top of the simple bus protocol. This segmentation allows the bus protocol to remain area-efficient with strong ordering while QoS support is provided by the separate priority propagation mechanism.
Solution Approach 2:
The patent introduces priority propagation as an intermediary layer between the simple strongly-ordered bus protocol and the quality of service requirements. This intermediary mechanism carries priority information upstream without requiring changes to the underlying bus protocol, allowing QoS support to be added while maintaining the area efficiency and strong ordering characteristics of the original protocol.
4Device complexity
If priority values are statically associated with transfer requests, then arbitration is simple at each node, but dynamic urgency changes cannot be accommodated and performance decreases
Solution Approach 1:
The patent introduces dynamics into the arbitration system by enabling priority values to change dynamically during request propagation. Instead of static priority associations, the system allows priority values to be updated and re-propagated as requests move through the bus matrix, accommodating changing urgency conditions while maintaining relatively simple arbitration node logic through incremental updates.
Solution Approach 2:
The patent changes the priority parameter from a static property to a dynamic one that can be modified during transmission. Priority values are initially associated with requests but can be updated as requests are propagated upstream, allowing the system to respond to changing conditions by modifying the priority parameter without requiring complex re-arbitration at each node.
Data Source
AI summary
A multi-matrix bus system is disclosed that provides proactive quality of service (QoS) by propagating, as soon as possible through an arbitration node in a network transfer request path, a highest priority value coming from an upstream arbitration node or master that has a current bus request pending at the arbitration node. The bus system ensures that any last downstream arbitration node knows at any time which is the highest priority request pending in the network transfer request path from the masters that are competing to share the bus layer switches and arbitration nodes in the network transfer request path.