Control Program Self-Test in Electronic Controllers After Rewriting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electronic control devices with secure boot functions are vulnerable to starting incorrect or tampered control programs due to potential errors in rewriting, posing a risk of improper operation.
Innovation Solution
Incorporating a memory unit with rewritable and non-rewritable regions, a control executing unit, and a test executing unit that executes tests on rewritten control programs using test data from the non-rewritable region to ensure normal operation by comparing calculated results with anticipated test results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the control program is made rewritable to allow updates, then the adaptability of the electronic control device is improved, but the reliability deteriorates due to risk of starting incorrect or tampered programs
Solution Approach 1:
The memory unit is divided into a rewritable region (for the control program) and a non-rewritable region (for test data and anticipated test results). This segmentation allows the control program to be updated while preserving immutable reference data for verification, thus resolving the contradiction between adaptability and reliability.
Solution Approach 2:
Test data and anticipated test results are pre-stored in the non-rewritable region before the control program is rewritten. This preliminary action ensures that verification data is available and cannot be tampered with, allowing safe program updates while maintaining reliability.
2Reliability
If a secure boot function is implemented to verify program authenticity, then the reliability is improved, but the device complexity increases due to additional verification mechanisms
Solution Approach 1:
The electronic control device performs self-verification by executing the control program with test data and comparing the actual test result with the anticipated test result stored in the non-rewritable region. This self-service approach simplifies the verification system by eliminating the need for external authentication mechanisms during normal operation.
Solution Approach 2:
The test data and anticipated test results are copied to a protected non-rewritable region, creating an immutable reference copy that can be used for verification without modifying the original program. This copying mechanism simplifies the verification process while maintaining reliability.
3Reliability
If test execution is performed after every control program rewrite, then the reliability is improved by detecting abnormal programs, but the productivity decreases due to additional testing time
Solution Approach 1:
Instead of comprehensive testing, the system performs a targeted partial test by executing only the control program with pre-stored test data and comparing the result with the anticipated outcome. This partial action approach provides sufficient verification to detect abnormal programs while minimizing the time penalty and preserving productivity.
Data Source
AI summary
The present disclosure discloses an electronic control device. The electronic control device includes a memory unit, a control executing unit, and a test executing unit. The memory unit includes a rewritable region, which stores a control program, and a non-rewritable region, which stores test data and an anticipated test result. The control executing unit acquires input data and calculates a control value by executing the control program using the input data. The test data corresponds to the input data. The test executing unit: executes the test by running the control program using the test data in response to rewriting of the control program; determines whether the control program after rewriting works normally by comparing a test result calculated based on the test data and the anticipated test result; and permits start of the control program according to the determining result.