EEPROM Storage Permission Flag for Vehicle Diagnosis Control
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Solution Overview
Problem
Conventional electronic control systems for vehicle diagnosis cannot accurately determine when to store diagnosis results in a rewritable nonvolatile memory, leading to unnecessary or erroneous data storage during vehicle manufacturing, and fail to prevent tampering with permanent diagnostic trouble codes.
Innovation Solution
An electronic control system that requires external storage permission to store diagnosis results in a rewritable nonvolatile memory, ensuring that only necessary data is stored after the vehicle is in use, using an EEPROM storage permission flag controlled by an external device or data center.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the ECU stores diagnosis results in rewritable nonvolatile memory without external permission control, then diagnosis results are automatically saved, but unnecessary or erroneous diagnosis results during manufacturing are stored
Solution Approach 1:
The system performs preliminary action by setting the storage permission flag to 'stored' before the vehicle is delivered to the user. This preliminary setting prevents unnecessary or erroneous diagnosis results from being stored during manufacturing and testing phases, while still allowing automatic storage of valid diagnosis results after the vehicle is put into service.
2Ease of manufacture
If the ECU allows storage of diagnosis results without external control, then storage is simple and fast, but the system cannot prevent tampering with permanent fault codes
Solution Approach 1:
The storage permission flag acts as an intermediary control mechanism between the ECU and the rewritable nonvolatile memory. This flag, which can be set by external devices or the data center, mediates the storage process to prevent unauthorized or erroneous data from being stored, thereby preventing tampering with permanent fault codes while maintaining simple storage operations.
3Reliability
If the ECU waits for a predetermined operating state to begin storage, then only valid diagnosis results are stored, but the storage time cannot be accurately determined
Solution Approach 1:
The system replaces the mechanical/time-based approach of waiting for predetermined operating states with an electronic control mechanism using the storage permission flag. This substitution allows the system to determine the exact moment when storage should begin (when the flag is set to 'stored') without relying on variable operating conditions, thereby eliminating time loss while ensuring only valid diagnosis results are stored.
4Adaptability or versatility
If the ECU uses operating conditions like vehicle travel speed to determine storage start, then storage can be controlled, but the condition varies from vehicle to vehicle and from user to user
Solution Approach 1:
The system changes the control parameter from variable operating conditions (vehicle travel speed, engine revolutions) to a fixed electronic control parameter (storage permission flag). This parameter change eliminates the inconsistency and variability that occur with operating condition-based control, while still maintaining flexibility through external device or data center control of the flag setting.
Data Source
AI summary
A vehicle diagnosis system includes an electronic control unit, which executes a diagnosing process for determining whether any abnormality is present in a vehicle based on signals from vehicle devices. When any abnormality is detected, the electronic control unit stores in an EEPROM a diagnosis result indicative of the abnormality when a storage permission flag in the EEPROM is in the on-state. The storage permission flag is turned on from the off-state when receiving a storage permission command from an external unit. Thus, the storage of the diagnosis result into the EEPROM may be permitted at the time of transmitting the storage permission command externally to the ECU.