Microcomputer Nonvolatile Memory Data Integrity Checking
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Solution Overview
Problem
During microcomputer operation, improper instruction codes can be executed due to errors like noise, leading to undesired data rewriting in nonvolatile memory, which cannot be recovered, causing abnormal operations and potential loss of original data.
Innovation Solution
A microcomputer system with a nonvolatile memory, a central processing unit, an abnormality detecting unit, and a nonvolatile memory checking unit that compares initial data with stored data to detect and correct any abnormalities, preventing undesired data rewriting and allowing for data recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a nonvolatile memory is used to store programs and data, then data can be saved nonvolatily and rewritten when necessary, but improper instruction codes can be executed due to errors like noise, leading to undesired data rewriting that cannot be recovered
Solution Approach 1:
The patent applies preliminary action by creating a backup of the original data before allowing rewriting operations. The backup storage unit stores a copy of the initial data, and the restoration unit can restore the original data from this backup if improper rewriting is detected. This preliminary backup action ensures that even if rewriting errors occur due to noise or improper instructions, the original data can be recovered.
Solution Approach 2:
The patent implements feedback through the abnormality detecting unit that monitors data rewriting operations and the restoration unit that compares current data with backup data. When an abnormality is detected (such as improper instruction code execution or noise-induced errors), the system provides feedback by restoring the original data from the backup storage unit, thereby correcting the error and maintaining data integrity.
2Reliability
If the boot program area is protected during normal operation, then the boot program cannot be accidentally modified, but it requires setting the microcomputer to a specific operation mode to execute the boot program for writing
Solution Approach 1:
The patent applies dynamics by implementing a mode switching mechanism that changes the operational state of the microcomputer. In normal operation mode, the boot program area is protected and cannot be accessed. When a specific operation mode (boot mode) is activated, the protection is temporarily lifted to allow the boot program to execute and write data. This dynamic switching between protected and accessible states resolves the contradiction between protection and ease of operation.
Solution Approach 2:
The patent applies preliminary anti-action by pre-establishing protection mechanisms on the boot program area during normal operation. The system proactively prevents unauthorized or accidental access to the boot program by blocking write operations in normal mode. Only when intentionally switched to boot mode, with proper authorization, can the protection be temporarily overridden to allow legitimate writing operations.
3Power
If a single-chip microcomputer integrates all functional blocks on one semiconductor substrate, then the system achieves high speed and low power consumption, but the ROM volume that can be mounted is limited
Solution Approach 1:
The patent applies parameter changes by transitioning from traditional ROM to nonvolatile memory (such as flash memory or MRAM) that offers higher storage density and rewritable capability. This parameter change in the memory technology enables the system to maintain the single-chip integration benefits (high speed, low power consumption) while significantly increasing the available storage volume for programs and data.
Data Source
AI summary
A microcomputer includes a plurality of functional blocks that exchange information with each other. A nonvolatile memory can rewrite information stored therein and first data has been written therein in advance. A central processing unit processes information read from the nonvolatile memory or writes information to the nonvolatile memory. An abnormality detecting unit detects an abnormality in exchange of data between the plurality of functional blocks. A nonvolatile memory checking unit reads the first data from the nonvolatile memory when the abnormality detecting unit has detected an abnormality, compares the first data with second data indicating the content of the first data when written to the nonvolatile memory, and detects an abnormality in the nonvolatile memory when a result of the comparison shows that the first data is not identical to the second data.