Microcontroller Self-Check Using Watchdog and Checksum Verification
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Solution Overview
Problem
Micro control chip manufacturers face significant burdens in ensuring that their chips meet safety check standards, as they need to provide detailed documentation for software and hardware updates, and there is a risk of excessive current causing danger due to false actions or malfunctions.
Innovation Solution
A self-check system and method that includes a memory storing a safety check program, a watchdog circuit, and a processing unit to periodically execute safety checks, reset the chip system if necessary, and verify checksum data to ensure the micro control chip operates safely and meets regulatory standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the manufacturer provides detailed documentation for software and hardware updates to meet safety standards, then the safety compliance is ensured, but the burden on manufacturers increases significantly
Solution Approach 1:
The micro control chip automatically performs self-check operations and generates execution records without external intervention. The system monitors its own safety-critical circuits, executes check programs, and stores results in memory, enabling it to serve its own safety verification needs without requiring manual documentation from manufacturers
Solution Approach 2:
The system implements a feedback mechanism where the processing unit continuously monitors the execution status of safety check programs, stores results in memory with execution flags, and provides this information to external inspection systems. This automated feedback loop replaces manual documentation processes while ensuring safety compliance
2Reliability
If the micro control chip performs periodic safety checks during operation, then dangerous malfunctions are prevented, but the system complexity increases
Solution Approach 1:
The processing unit serves multiple functions: it executes both main applications and safety check programs, manages memory operations, controls the watchdog circuit, and generates execution records. This multi-functionality allows the system to perform safety checks without adding dedicated separate hardware components, thereby limiting the increase in system complexity
Solution Approach 2:
The safety check system is merged with the existing micro control chip architecture. The check programs are stored in the same memory as main applications, the processing unit handles both safety and application tasks, and the watchdog circuit is integrated into the system. This consolidation achieves safety functionality without proportionally increasing overall system complexity
3Reliability
If the watchdog circuit is used to trigger reset when counting value overflows, then the chip system is protected from false actions, but the risk of excessive current causing danger remains
Solution Approach 1:
The system performs preliminary safety checks on power supply circuits, control signals, and other safety-critical functions before they can cause harmful effects. The processing unit executes check programs that detect potential failures in advance, and the watchdog circuit is configured to trigger reset before excessive current or dangerous conditions can develop
Solution Approach 2:
The system implements protective measures in advance by continuously monitoring safety-critical circuits and preparing reset mechanisms. The watchdog circuit maintains a counting mechanism that will trigger reset if the processing unit fails to respond, providing a cushioning protection layer that prevents false actions from developing into dangerous conditions
Data Source
AI summary
A self-check system and a method thereof are disclosed. In the self-check system, a memory stores a safety check program, a main application program and a predetermined checksum data. The safety check program include a circuit check program, a watchdog circuit reset program and a checksum check program. When a chip system is powered on, a processing unit executes the main application program, and then executes an interrupt call to generate an interrupt, so as to execute the safety check program and the circuit check program to check a to-be-checked circuit. The processing unit also executes the watchdog circuit reset program to reset a counting value of a watchdog circuit. The processing unit also executes the checksum check program to calculate a checksum data of the first safety check program, and reset the chip system when the calculated checksum data is not equal to the predetermined checksum data.