NAND Flash Controller Advance Reading Mechanism
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Solution Overview
Problem
Conventional memory devices, particularly NAND-type flash memory systems, face inefficiencies in reading operations, leading to longer data retrieval times due to sequential access patterns and lack of optimized commands for consecutive page reads.
Innovation Solution
The implementation of an advanced reading operation within the memory system that proactively issues commands for consecutive page reads, utilizing a controller to manage data transfer between the NAND-type flash memory and the host, reducing busy states and enhancing data transfer efficiency by using specific commands and register settings to switch between normal and advance reading modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional sequential reading operations are used in NAND-type flash memory, then the memory device can read data reliably, but the data retrieval time becomes excessively long
Solution Approach 1:
The patent applies preliminary action by issuing a second read command for a consecutive page before the first read command completes. The controller proactively prepares the next data transfer operation in advance, so that when the first page reading finishes, the second page is already ready to be transferred, thereby reducing idle time and accelerating sequential data retrieval
Solution Approach 2:
The patent implements continuity of useful action by overlapping the execution of multiple read commands. Instead of waiting for one read operation to complete before starting the next, the controller initiates subsequent read commands during the data transfer phase of previous commands, ensuring that the memory device continuously performs useful reading operations without idle gaps
2Speed
If the controller waits for each reading operation to complete before issuing the next command, then command execution is simple, but the overall reading speed decreases
Solution Approach 1:
The controller issues the second read command in advance during the data transfer phase of the first command, rather than waiting for completion. This preliminary command issuance requires tracking command states and timing, increasing controller complexity but enabling faster sequential reading by eliminating idle wait periods
Solution Approach 2:
The patent introduces dynamic command management where the controller adaptively overlaps read commands based on timing conditions. The controller monitors data transfer progress and dynamically determines when to issue subsequent commands, creating a flexible rather than rigid command execution sequence that optimizes reading speed
3Productivity
If advance reading commands are issued for consecutive pages, then data transfer efficiency improves, but the risk of errors increases when host requests do not match prepared data
Solution Approach 1:
The controller proactively issues read commands for consecutive pages assuming sequential access patterns. However, it maintains the ability to abort or adjust these preliminary commands if the host device requests non-sequential data, thus balancing the benefits of advance preparation with the flexibility to maintain data reading accuracy when access patterns differ from expectations
Data Source
AI summary
A memory device includes a semiconductor memory unit, and a controller configured to communicate with a host through a serial interface and access the memory semiconductor unit in response to commands received through the serial interface. The controller, in response to a first read command received through the serial interface to read data in a first page of the semiconductor memory unit, issues a first command to the semiconductor memory unit to read data in the first page and, in addition, a second command to read data in a second page that is consecutive to the first page and not specified in the first read command.