Flash Memory Block Management Value Digit Shift for Power Reset Reliability
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Solution Overview
Problem
Flash memory devices face issues with accurately reading updated values during power resets, as multiple blocks can become active, leading to erroneous data retrieval due to inconsistent block management value representation and random cell discharge.
Innovation Solution
Implementing a memory control unit that manages block management values with specific digit shifts and initial values to differentiate active and unused states, ensuring correct data reading by prioritizing blocks with larger management values and restricting reading from blocks with specific invalid values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If block management values are used to manage memory blocks, then block usage status can be tracked, but multiple blocks may become active during power resets leading to erroneous data retrieval
Solution Approach 1:
The patent applies preliminary action by setting the least significant bit of the block management value to '1' in advance for all active blocks before any write operation. This preliminary marking ensures that during power reset scenarios, the system can immediately identify which block contains the true updated value by checking this pre-set bit, preventing erroneous data retrieval without requiring complex real-time arbitration mechanisms.
Solution Approach 2:
The patent applies local quality by differentiating block management through specific bit patterns. The least significant bit serves as a local identifier that distinguishes the true active block from other blocks that may appear active during power resets. This localized quality marker enables reliable data retrieval by focusing validation on a specific bit position rather than requiring comprehensive block comparison.
2Manufacturing precision
If cells are discharged to update block management values, then unused state can be indicated, but random discharge speeds cause inconsistent block management values during maintenance
Solution Approach 1:
The patent applies parameter changes by modifying the block management value structure to use hexadecimal digits where 'F' represents the initial/unused state and '0' represents the active state. This parameter transformation converts the random discharge issue into a controlled state representation: when cells are discharged, the value transitions predictably toward '0' patterns, and the least significant bit setting ensures consistent identification regardless of discharge timing. This resolves the inconsistency caused by varying cell discharge speeds.
3Loss of information
If updated values are copied during maintenance, then data can be preserved, but power resets during copying result in unknown updated values from multiple active blocks
Solution Approach 1:
The patent applies preliminary action by setting the least significant bit of the block management value to '1' before initiating any copy operation during maintenance. This pre-marking ensures that even if power is reset during the copy process, the system can identify which block contains the true updated value after reset by checking this pre-set bit, preventing loss of information and ensuring updated value accuracy.
Solution Approach 2:
The patent applies feedback by using the least significant bit as a validation marker that provides immediate feedback about which block contains valid updated data. After power reset, the system reads this bit to determine which block to trust, creating a feedback loop that ensures correct data retrieval even when maintenance operations are interrupted.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ensures accurate reading of updated values even during power resets by maintaining the true updated value in the correct block, preventing erroneous data retrieval and ensuring data integrity during maintenance.
Implementation Method 1
each of the cells stores a single bit of '0' when the accumulated charge is greater than or equal to a threshold Th and stores a single bit of '1' when the accumulated charge is less than the threshold Th
Data Source
AI summary
In a flash memory device, after an updated value is copied from a first block to a second block, a block management value of the first block is set to an unused state, and maintenance is performed to erase data from the first block. When performing maintenance, the block management value of the first block B1 is rewritten from “$FFF0” to “$FFFF.” When a reset occurs and the power supply is deactivated during the maintenance, the digit of “$0” in the block management value may become “1” to “E” of the hexadecimal system. In this manner, when the block management value includes a single digit of “1” to “E” and three digits of “F,” the reading of an updated value from the block corresponding to the block management value is restricted.