Clock Supervision Using an Auxiliary Reference for Fault Detection
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Solution Overview
Problem
Existing electronic systems in vehicles, particularly those with multiple microcontroller units (MCUs), face challenges in reliably detecting and responding to clock faults, such as missing or deviating clock frequencies, which can lead to safety-critical failures and hinder diagnostic operations.
Innovation Solution
A clock supervision unit with an auxiliary and deviation unit, capable of independently analyzing clock signals using a monitor clock, allowing for autonomous reaction to clock faults and classification of fault severity, thereby initiating appropriate error handling procedures, including shutdowns or software-based corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If all clocks are derived from a system clock and fault detection relies on the system clock, then the system structure is simple, but the detection reliability deteriorates when the system clock fails
Solution Approach 1:
The patent introduces an auxiliary clock as an intermediary reference that is independent of the system clock. The auxiliary clock serves as a mediator to detect system clock faults without being affected by system clock failures. When the system clock fails, the auxiliary clock provides a stable reference for the activity unit to detect the absence or frequency deviations of the system clock, thereby resolving the reliability issue while maintaining relatively simple system structure.
2Ease of operation
If the system uses a single reference clock for fault detection, then the system is simple to operate, but the ability to classify and respond to different fault types deteriorates
Solution Approach 1:
The patent segments the fault detection function into multiple independent units: the activity unit detects presence/absence faults, the deviation unit detects frequency deviation faults, and the classification unit categorizes fault severity. This segmentation allows the system to operate simply through modular components while achieving versatile fault classification by combining their outputs to distinguish between critical and non-critical faults.
3Device complexity
If clock fault detection is performed without an auxiliary reference clock, then the device complexity is low, but the measurement precision of clock fault detection deteriorates
Solution Approach 1:
The patent creates a copy of the clocking function through the auxiliary clock, which replicates the timing reference functionality independently from the system clock. The auxiliary clock provides a copied reference signal that enables precise measurement of system clock characteristics without adding complex detection circuitry, as the comparison between the original system clock and its auxiliary copy enables accurate fault detection.
Data Source
AI summary
The present invention relates to a clock supervision unit (100) and an electronic system clocked by at least one clock (c*) and using the clock supervision unit (100). The clock supervision unit (100) analyzes the at least one clock (c*) based on a monitor clock (m*) provided together with the at least one clock (c*) or separately to the clock supervision unit (100). The clock supervision unit (100) at least comprises an activity unit (210), a deviation unit (220) and an auxiliary clock generator (240). The auxiliary clock generator (240) outputs an auxiliary clock (a*). The activity unit (210) detects the presence of the monitor clock (m*) based on the auxiliary clock (a*) and the presence of the auxiliary clock (a*) based on the monitor clock (m*). The deviation unit (220) detects clock faults in the monitor clock (m*) based on the auxiliary clock (a*). With the clock supervision unit (100) according to the present invention, the at least one clock (c*) can be supervised in more detail and it is possible to react on different clock faults in the at least one clock c* with different error handling procedures, e.g. by initiating a shutdown of the devices controlled by the electronic system.