SD Card Hot-Swap Detection via Polling Feedback
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Solution Overview
Problem
Linux operating systems fail to detect real-time hot-swapping events of Secure Digital (SD) cards, leading to application confusion and read/write failures when SD cards are removed from an SD card reader, as upper-layer applications remain unaware of the removal and continue to access non-existent cards.
Innovation Solution
A detection method and apparatus that transmits an inquiry command to the SD card at a predetermined frequency, receives and compares command return messages to determine the presence or absence of the SD card, and updates the status accordingly, allowing for real-time detection and notification to upper-layer applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the Linux operating system uses conventional SD card detection methods, then the system structure remains simple, but hot-swapping events cannot be detected in real-time
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously sends inquiry commands to the SD card and compares return messages with previous states. This feedback loop enables real-time detection of hot-swapping events by monitoring changes in the card's presence status, resolving the contradiction between simple structure and real-time detection capability.
Solution Approach 2:
The patent employs continuous polling at predetermined frequencies to maintain constant contact with the SD card. This continuous action ensures that any changes in card presence are captured immediately, achieving real-time detection without requiring complex event-triggered mechanisms, thus balancing detection accuracy with system simplicity.
2Reliability
If upper-layer applications continue to access the SD card without detection, then application operation remains uninterrupted, but read and write failures occur when the card is removed
Solution Approach 1:
The detection mechanism provides real-time feedback to upper-layer applications about the SD card's presence status. When the card is removed or inserted, the system notifies applications of the status change, allowing them to adjust their operations accordingly. This prevents read/write failures while minimizing interruption to application functionality.
Solution Approach 2:
The system performs preliminary detection of card presence before allowing applications to access the card. By checking the card's status in advance and notifying applications beforehand, the system prevents access attempts to non-existent cards, avoiding failures while maintaining operational continuity through proactive status management.
3Measurement precision
If the system implements continuous monitoring of SD card status, then hot-swapping detection accuracy is improved, but resource consumption increases
Solution Approach 1:
The patent implements periodic monitoring at predetermined frequencies rather than continuous monitoring. This periodic action maintains detection accuracy by checking card presence at regular intervals while significantly reducing resource consumption compared to constant monitoring. The system strikes a balance between detection precision and energy efficiency through optimized polling intervals.
Data Source
AI summary
A detection method for hot-swapping of a Secure Digital (SD) card is provided. The detection method includes steps of: transmitting an inquiry command to an card reader at a predetermined frequency; receiving a command return message replied in response to the inquiry command; determining whether the SD card is removed or plugged according to the command return message; and detecting a hot-swapping status of the SD card in real-time to provide an accurate status of the SD card for upper-layer applications.