ECU Data Protection Against Improper Reset
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Solution Overview
Problem
Electronic control units face data loss due to instantaneous power supply interruptions, which can reset the microcomputer and prevent data stored in battery-backed RAM from being written to non-volatile memory, leading to loss of operational data and impaired fault analysis capabilities.
Innovation Solution
An electronic control unit with a RAM work area and non-volatile memory, utilizing a controller to store data in both the RAM and non-volatile memory, with a save area for data protection during improper resets, ensuring data is written to the non-volatile memory when operation stops and read back into RAM upon restart.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is stored only in battery-backed RAM, then data can be continuously updated during operation, but data is lost when instantaneous power supply interruption occurs
Solution Approach 1:
The system performs preliminary data backup by continuously writing data from RAM to non-volatile memory during normal operation. This preliminary action ensures that data is preserved before power interruption occurs, resolving the contradiction between continuous data updates and data retention reliability during power failures.
Solution Approach 2:
The system creates a copy of data from battery-backed RAM and stores it in non-volatile memory. This copying mechanism ensures that even if power is interrupted and RAM data is lost, the copied data in non-volatile memory remains intact, thereby preventing data loss while maintaining continuous data updates.
2Reliability
If data is written to non-volatile memory during operation, then data protection is improved, but processing time increases due to additional write operations
Solution Approach 1:
Instead of writing data to non-volatile memory continuously or at every operation, the system uses periodic action by writing data at predetermined intervals or when specific conditions are met. This reduces the frequency of write operations, thereby decreasing processing time overhead while still maintaining adequate data protection capability.
Solution Approach 2:
The system changes the parameter of data writing frequency based on operational conditions. By dynamically adjusting when and how often data is written to non-volatile memory, the system optimizes between data protection reliability and processing time efficiency, writing more frequently when data is critical and less frequently when stability is maintained.
3Reliability
If shutdown processing is performed to write data to non-volatile memory, then data is protected from power interruption, but data is lost when improper reset occurs before shutdown completes
Solution Approach 1:
The system performs preliminary data backup to non-volatile memory before improper reset can occur by continuously writing data during operation. This preliminary action ensures that even if shutdown processing is interrupted by improper reset, the data has already been protected in non-volatile memory, preventing data loss.
Solution Approach 2:
The system provides beforehand cushioning by maintaining continuous data backup operations during normal operation. This creates a protective buffer that ensures data is already secured in non-volatile memory before any power interruption or improper reset occurs, thereby cushioning against potential data loss scenarios.
Data Source
AI summary
An ECU includes a RAM; a non-volatile memory; and a controller for controlling reading of data from, and writing of data into, the RAM and non-volatile memory. The controller is configured to: store data generated during operation into the RAM, write the data into a storage area of the non-volatile memory when the operation stops, and read the data from the non-volatile memory into the RAM when the operation starts, and control a control target using the data. When determining that an improper reset is expected, the controller writes at least part of the data generated during the operation and stored in the RAM into a save area, different from the data storage area, of the non-volatile memory. When the operation restarts from the improper reset, the controller reads, into the RAM, the data that has been written in the storage and save areas.