Watchdog Timer Segmentation for Interrupt Abnormality Detection
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Solution Overview
Problem
In multiple-interrupt systems, detecting abnormal operations caused by interrupt processing is challenging, especially when multiple interrupts occur in parallel or at the same priority level, as existing systems lack effective mechanisms for automatic recovery and cause analysis.
Innovation Solution
Implementing a watchdog timer (WDT) system with predetermined time-out values for each interrupt priority, where WDTs are started at the time of interrupt requests, and prioritizing interrupt requests based on the timeout of lower-priority WDTs to detect abnormal operations accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single WDT is used to monitor system operation, then the system structure remains simple, but the ability to detect abnormal operations in multiple-interrupt systems deteriorates
Solution Approach 1:
The patent divides the single WDT into multiple WDTs, with each WDT corresponding to a specific interrupt priority level. This segmentation allows each WDT to independently monitor the timing of interrupts at its priority level, enabling precise detection of abnormal operations in multiple-interrupt systems while maintaining manageable system complexity through structured organization.
Solution Approach 2:
Each WDT is configured with specific local characteristics tailored to its corresponding interrupt priority level. The WDTs have different time-out values and monitoring scopes according to their priority levels, allowing optimized detection for specific interrupt scenarios rather than a one-size-fits-all approach.
2Measurement precision
If multiple WDTs are provided for different interrupt priorities, then abnormal operation detection capability improves, but the system complexity increases
Solution Approach 1:
Each WDT is designed to serve multiple functions: it monitors timing for its specific interrupt priority level, detects abnormal operations, and can trigger appropriate responses. The WDTs collectively provide comprehensive monitoring across all interrupt priorities while each individual WDT remains a standardized component with well-defined behavior.
Solution Approach 2:
The WDTs are pre-configured with appropriate time-out values before the system operates. This preliminary setup ensures that each WDT is ready to detect abnormal operations at its priority level without requiring complex runtime configuration, simplifying the overall system management.
3Speed
If interrupt processing is suspended for higher-priority interrupts, then real-time responsiveness improves, but the detection of suspended interrupt abnormalities becomes difficult
Solution Approach 1:
The patent segments the interrupt monitoring into separate WDTs for each priority level. When an interrupt is suspended, its corresponding WDT continues to run independently and can detect abnormalities in the suspended interrupt processing. This segmentation allows simultaneous high-priority interrupt response and monitoring of lower-priority suspended interrupts.
Solution Approach 2:
The WDTs provide continuous feedback on the timing status of interrupt processing at each priority level. When an interrupt is suspended or abnormal conditions occur, the WDT generates signals that can trigger appropriate responses, including detection and reporting of abnormal operations in suspended interrupt processing.
Data Source
AI summary
A controller for controlling interrupt processing in a multiple-interrupt system is provided. The controller includes multiple watchdog timers (WDTs), each provided for each of interrupt priorities. The controller includes interrupt priority selectors, each of which receives each interrupt request signal and outputs an activation signal to a corresponding WDT according to the priority of the interrupt request signal. The controller includes an interrupt processing circuit, which when a WDT has timed out, outputs, to a processor, an interrupt request signal having a priority one or more levels higher than the priority corresponding to the WDT. When multiple causes of interrupt are assigned to one of the interrupt priorities, the interrupt processing circuit gives priority to an interrupt request signal caused by the timeout of a WDT lower in priority level than the interrupt priority to detect that an abnormal operation has occurred in interrupt processing having the lower level priority.