Multi-Mode Task Monitoring Circuit for Diagnostic Coverage
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Solution Overview
Problem
Current automotive microcontrollers require significant design effort and computational load to implement hardware support for logical and temporal flow monitoring, as specified by the ISO26262 standard, which is necessary for achieving high diagnostic coverage.
Innovation Solution
A circuit and method for logical and temporal task monitoring that includes a task management circuit and a task recording circuit, capable of operating in multiple modes to check task execution states and durations, reducing the need for additional resources and increasing flexibility in control flow checkpoint insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hardware support for logical and temporal flow monitoring is implemented in automotive microcontrollers, then diagnostic coverage is improved, but design effort and computational load increase significantly
Solution Approach 1:
The monitoring circuit autonomously performs logical and temporal flow monitoring without requiring external software intervention. The circuit self-manages checkpoint detection, task state verification, and error signaling, eliminating the need for software to implement monitoring logic and reducing computational burden on the microcontroller core.
Solution Approach 2:
A dedicated monitoring circuit is introduced as an intermediary component between the task execution units and the diagnostic system. This circuit receives task state signals, performs monitoring operations, and generates diagnostic outputs, thereby isolating the complex monitoring functions from the main processor and reducing its computational load.
2Reliability
If hardware support for logical and temporal flow monitoring is implemented in automotive microcontrollers, then diagnostic coverage is improved, but computational load increases significantly
Solution Approach 1:
The monitoring circuit autonomously performs logical and temporal flow monitoring without requiring external software intervention. The circuit self-manages checkpoint detection, task state verification, and error signaling, eliminating the need for software to implement monitoring logic and reducing computational burden on the microcontroller core.
Solution Approach 2:
Software-based monitoring operations are replaced with hardware circuit operations. The monitoring functions that would traditionally require CPU execution of monitoring code are instead performed by dedicated hardware logic, significantly reducing computational load and energy consumption.
3Reliability
If control flow checkpoints are inserted with adequate granularity to reach requested diagnostic coverage, then diagnostic coverage is improved, but runtime computational load increases proportionally
Solution Approach 1:
The monitoring circuit autonomously performs logical and temporal flow monitoring without requiring external software intervention. The circuit self-manages checkpoint detection, task state verification, and error signaling, eliminating the need for software to implement monitoring logic and reducing computational burden on the microcontroller core.
4Reliability
If software countermeasures for logical and temporal flow monitoring are implemented, then diagnostic coverage is improved, but design effort and runtime computational load increase
Solution Approach 1:
Software-based monitoring operations are replaced with hardware circuit operations. The monitoring functions that would traditionally require CPU execution of monitoring code are instead performed by dedicated hardware logic, significantly reducing computational load and energy consumption.
Solution Approach 2:
The monitoring circuit autonomously performs logical and temporal flow monitoring without requiring external software intervention. The circuit self-manages checkpoint detection, task state verification, and error signaling, eliminating the need for software to implement monitoring logic and reducing computational burden on the microcontroller core.
Data Source
AI summary
A monitoring circuit performing logical and temporal task monitoring of a plurality of tasks comprises a task recording circuit and a task management circuit receiving as input a plurality of task signals, each task signal being indicative of an execution state of a respective task. The task management circuit comprises a managing circuit configured to operate in at least three modes depending on a respective event corresponding to either detection of a rising edge of a given task signal, occurrence of a trigger signal, or detection of a falling edge of a given task signal being monitored. In each mode the managing circuit is configured to check whether a variable representing the operation state of the task contains an expected value corresponding to the occurrence of the event enabling the respective mode, and output a result of the check operation in an error signal for the given task being monitored.