Vehicle CPU State Judgment via Inter-CPU Communication and Voltage Monitoring
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Solution Overview
Problem
Conventional control devices for vehicle-mounted apparatuses face challenges in judging whether a CPU is in a reset state or experiencing abnormal inter-CPU communication, leading to difficulties in appropriate control during resets and potential operational instability.
Innovation Solution
Incorporating state judging sections within each CPU to assess the state based on inter-CPU communication and power supply voltage, allowing for accurate determination of CPU states and enabling appropriate control measures during resets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If only one CPU is reset at a time, then operational stability is improved, but the ability to judge CPU state deteriorates due to shut off inter-CPU communication
Solution Approach 1:
A reset signal output section is introduced as an intermediary component that outputs reset signals to both CPUs simultaneously. This mediator allows the system to maintain inter-CPU communication during reset operations, enabling the judging section to accurately determine CPU states while preserving operational stability.
Solution Approach 2:
The judging section continuously monitors inter-CPU communication status and provides feedback about CPU states. By using the communication status as feedback, the system can distinguish between a CPU that is intentionally reset versus one that has failed, resolving the detection difficulty caused by selective resetting.
2Ease of operation
If both CPUs are reset simultaneously, then control intervention capability is improved, but operational stability deteriorates
Solution Approach 1:
The system dynamically adjusts the resetting strategy based on operational needs. The reset signal output section can output reset signals to both CPUs simultaneously when control intervention is needed, while the judging section dynamically monitors communication status to maintain stability by identifying and handling reset states appropriately.
3Ease of manufacture
If inter-CPU communication is shut off during reset, then reset operation is simplified, but the ability to distinguish reset state from abnormal state deteriorates
Solution Approach 1:
The reset signal output section acts as an intermediary that maintains communication pathways open during reset operations. This allows the judging section to receive continuous feedback about CPU states through the communication interface, enabling precise distinction between reset states and abnormal states without complicating the reset operation.
Solution Approach 2:
The system replaces physical isolation methods (mechanically shutting off communication) with signal-based detection (electronic monitoring of communication status). The judging section uses software/firmware logic to interpret communication patterns and determine CPU states, achieving accurate state distinction without physical communication shutdown.
Data Source
AI summary
A control device for a vehicle-mounted apparatus, the control device includes: a second CPU state judging section provided to the first CPU, and configured to judge a state of the second CPU based on a state of the inter-CPU communication and a voltage value of the electric power supplied from the first electric power supply section, or the second reset signal; and a first CPU state judging section provided to the second CPU, and configured to judge a state of the first CPU based on the state of the inter-CPU communication and a voltage value of the electric power supplied from the second electric power supply section, or the first reset signal.