Bus Guardian Clock Synchronization for Network Efficiency
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Solution Overview
Problem
In distributed real-time computer systems using time-triggered communications protocols, the need for independent clock sources in communication controllers and bus guardians leads to increased costs and reduced efficiency due to the requirement for long 'interframe gaps' to prevent data packet overlap, which can result in low data transmission efficiency, especially in applications like automobile technology.
Innovation Solution
A communications network where the bus guardian is continuously synchronized with the global clock signal of the communication controller, eliminating the need for a precise clock oscillator in the bus guardian, and using watchdog circuits to monitor clock signals and prevent unauthorized access, allowing for tight time tolerances and short 'interframe gaps' without compromising fault-silent properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bus guardian uses an independent clock source, then the fail-silent property is ensured through independent monitoring, but the interframe gaps must be enlarged to accommodate clock frequency deviations, reducing data transmission efficiency
Solution Approach 1:
The patent merges the clock source of the bus guardian with the communication controller, eliminating the need for an independent clock oscillator in the bus guardian. The bus guardian uses the communication controller's clock signal, synchronized via the ARM signal, to generate its timing. This combination allows the system to maintain fail-silent properties through software-based monitoring while enabling shorter interframe gaps, thus improving data transmission efficiency.
2Ease of operation
If the bus guardian uses an independent clock source, then autonomous operation is achieved, but system costs increase due to additional clock oscillators
Solution Approach 1:
The communication controller's clock source serves dual purposes: it provides timing for the communication controller itself and also serves as the timing basis for the bus guardian. This multi-functionality eliminates the need for a separate clock oscillator in the bus guardian, reducing system cost while maintaining the bus guardian's ability to autonomously monitor and control bus access according to the communications schedule.
3Reliability
If the bus guardian uses an independent clock source, then independent time base is available for monitoring, but interframe gaps must be dimensioned for long-term stability, reducing efficiency
Solution Approach 1:
The system implements feedback-based synchronization where the bus guardian receives the ARM signal from the communication controller, which contains timing information based on the communication controller's clock. The bus guardian uses this feedback to adjust its timing and generate accurate time slots for monitoring, eliminating the need for large safety margins in interframe gaps while maintaining long-term timing accuracy.
Data Source
AI summary
The invention relates to a communications network with at least two network nodes, between which data may be transmitted via a transmission medium,in which a communications schedule is provided which allots time slots to the network nodes for access to the transmission medium,in which the network nodes each comprise at least one communication controller with a first scheduler for controlling access by the network nodes to the transmission medium according to the communications schedule,in which the communications network comprises at least one bus guardian with a second scheduler for monitoring accesses by the network nodes to the transmission medium according to a monitoring schedule,in which the communication controller comprises means for generating a local, independent clock signal and a global clock signal, which may be influenced by at least one parameter of the communications system andin which the global clock signal is provided both to control the first schedulers of the communication controllers and to control the second scheduler of the bus guardian.