USB Power Cut Notification via Master-Device Messaging
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Solution Overview
Problem
USB devices conforming to the USB 2.0 standard lack a mechanism to anticipate and prepare for impending power failures, which can lead to data corruption or malfunction due to the absence of notification to connected equipment.
Innovation Solution
A method is implemented where the master computer in a USB network sends an information message about an imminent power cut to connected USB devices, specifying the available time for preparation, and this message is transmitted three times at a fixed interval of 50 milliseconds to ensure the devices can prepare for the power failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If USB devices conforming to USB 2.0 standard are used, then compatibility and ease of operation are improved, but reliability deteriorates due to absence of power cut notification mechanism
Solution Approach 1:
The master computer performs preliminary actions by detecting imminent power cuts and sending notification messages to USB devices before the actual power cut occurs. This allows USB devices to execute preparation routines such as saving data to non-volatile memory, flushing buffers, and completing pending operations, thereby preventing data corruption and maintaining reliability while preserving USB 2.0 compatibility
Solution Approach 2:
The system implements a feedback mechanism where the master computer monitors power supply status and provides feedback to USB devices through standardized USB communication protocols. When power instability is detected, the master computer sends notification messages that trigger USB devices to execute protective actions, creating a closed-loop system that maintains data integrity without requiring hardware modifications
2Reliability
If power cut notification mechanism is implemented, then reliability is improved, but device complexity increases
Solution Approach 1:
The notification mechanism leverages the existing USB communication infrastructure to serve multiple functions: standard data communication, power management, and power cut notification. By utilizing standardized USB message protocols that USB devices already support, the system achieves reliable power cut notification without adding dedicated hardware or complex proprietary communication layers, thereby minimizing device complexity while improving reliability
3Reliability
If data saving procedures are initiated before power cut, then data integrity is improved, but loss of time increases
Solution Approach 1:
The system performs data protection actions in advance when power instability is first detected, rather than waiting until the last moment. The master computer sends notification messages that trigger USB devices to initiate data saving procedures early, allowing sufficient time for flushing buffers, writing data to non-volatile memory, and completing pending operations before the actual power cut, thereby minimizing data loss risk while optimizing the use of available preparation time
Data Source
Figure 1
AI summary
The invention relates to a method for securing the cutting off of the power supply to a USB device, implemented on a USB network by means of which a network master computer and at least one slave USB device of the network are interconnected. According to the invention, when information on the imminent cutting of the power supply to the USB device is known by said computer, said method comprises implementation of the following successive steps: - sending by the computer of an information message (MG) on the USB network, containing information on the cutting of the power supply of the USB device; - reception of the information message (MG) by the USB device; - implementation by the USB device of a method of preparing the USB device for the imminent cutting of the power supply.