On-vehicle ECU Flash Memory Block Segmentation for Data Management
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Solution Overview
Problem
Conventional on-vehicle electronic control units face challenges in efficiently utilizing flash memory for data storage, as they require frequent batch clears, leading to reduced operation life and increased costs due to the need for multiple types of memories, making the system complex and expensive.
Innovation Solution
The proposed solution involves using a flash memory as both program and data memory, with a control constant processing program that allows for initial transfer writes, sequential updates, and batch clears, dividing the memory into two blocks: one for semi-fixed control constants and another for variable control constants, optimizing the number of batch clears and extending the memory's rewrite capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If flash memory is used as both program and data memory, then device complexity is reduced and cost is lowered, but the number of batch clears required increases, reducing operation life
Solution Approach 1:
The flash memory is divided into two distinct blocks: a first block for storing semi-fixed control constants and a second block for storing variable control constants. This segmentation allows different write strategies to be applied to each block, reducing the frequency of batch clears and extending operation life while maintaining the simplified single-memory-structure benefit.
Solution Approach 2:
Different regions of the flash memory are assigned different characteristics and usage patterns. The first block is optimized for semi-fixed data with lower write frequency, while the second block handles variable data with higher write frequency. This local differentiation allows each region to be managed optimally, balancing complexity reduction with operation life extension.
2Quantity of substance
If flash memory is used instead of EEPROM, then cost is reduced and capacity is increased, but the number of rewrite times is limited due to batch clear requirements
Solution Approach 1:
By segmenting flash memory into first and second blocks with different purposes, the system can preserve reliability for critical semi-fixed data in the first block while utilizing the high-capacity advantage of flash memory in the second block for variable data, achieving both capacity increase and reliability maintenance.
Solution Approach 2:
The system changes the management parameter of flash memory by implementing differentiated write strategies for different blocks. The first block uses a conservative approach to preserve rewrite life, while the second block utilizes flash memory's full capacity potential, effectively changing how flash memory parameters are optimized for different data types.
3Reliability
If multiple types of memories are used to maintain operation life, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
Rather than using multiple separate memory types, the invention segments a single flash memory into functionally distinct blocks. This achieves the reliability benefits of differentiated memory management while avoiding the complexity and cost of multiple memory types, as both blocks use the same flash memory technology with different management strategies.
Solution Approach 2:
A single flash memory unit performs multiple functions by serving as both program memory and data memory, with internal segmentation allowing it to handle both semi-fixed and variable control constants. This multi-functionality eliminates the need for separate memory components while maintaining operational reliability through differentiated block management.
Data Source
AI summary
A microprocessor of an on-vehicle electronic control unit controls an on-vehicle current consumer group responsive to input signals of on-vehicle sensor groups based on control program, fixed control constant and semi-fixed control constant respectively stored in first block of a no-volatile memory, and variable control constant having been transferred from second block of the no-volatile memory to RAM memory; and content of RAM memory is learned and compensated during operation. When power supply switch is OFF, contents of the RAM memory are sequentially added to and written in the second block. When the second block is filled up to capacity, batch clear is executed and, thereafter, the latest data is written. Thus, a flash memory divided into the first and second blocks capable of executing batch clear separately is employed as a non-volatile memory, enabling to perform save processing many times with small number of times of batch clear.