USB Host Speed Control for Incompatible Device Detection
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Solution Overview
Problem
Existing USB communication technologies fail to prevent data loss due to communication errors during high-speed data transfer, particularly in isochronous transfers for audio and video, as they do not effectively switch to low-speed modes when incompatible devices are connected, leading to issues like audio and video dropouts.
Innovation Solution
Storing specification information of incompatible external devices in a list storage unit and setting data communication speed to low-speed mode upon connection, ensuring communication errors are minimized by avoiding high-speed mode when such devices are detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high-speed mode (HS mode) is used for data communication, then communication speed is improved, but communication errors occur when incompatible devices are connected
Solution Approach 1:
The patent applies preliminary action by detecting the device type before starting high-speed data communication. The host computer identifies whether the connected device is compatible with HS mode through specification information retrieval and comparison before initiating data transfer. This preventive measure avoids communication errors by selecting appropriate communication mode in advance, rather than attempting HS mode and correcting errors afterward.
Solution Approach 2:
The patent implements parameter changes by dynamically selecting the communication speed parameter based on device compatibility. When an incompatible device is detected, the system switches from HS mode (high speed parameter) to FS mode (full-speed mode, lower speed parameter). This parameter adjustment resolves the contradiction by adapting the communication speed to match the device's capabilities, ensuring reliable communication while maintaining high speed when possible.
2Reliability
If communication speed is switched from HS mode to FS mode to prevent errors, then communication reliability is improved, but data loss occurs during isochronous transfers due to inability to retry
Solution Approach 1:
The patent applies preliminary action by determining device compatibility and selecting the appropriate communication mode before isochronous data transfer begins. By identifying incompatible devices in advance and switching to FS mode beforehand, the system prevents communication errors from occurring during the transfer, thereby avoiding data loss. This is particularly critical for isochronous transfers where data cannot be retried, making preliminary mode selection essential for both reliability and data integrity.
3Reliability
If device compatibility information is stored and checked before communication, then communication reliability is improved, but device complexity increases due to additional detection and identification processes
Solution Approach 1:
The patent applies the copying principle by using pre-stored specification information (vendor ID, product ID) as a simplified representation of device compatibility characteristics. Instead of performing complex real-time compatibility analysis, the system retrieves and compares pre-existing device profiles stored in memory. This copying approach maintains reliability by using comprehensive compatibility data while reducing complexity by avoiding complex computational analysis during the communication setup process.
Data Source
AI summary
A communication speed control apparatus for controlling communication between a host device and an external device in accordance with a high-speed communication mode or a low-speed communication mode includes a list storage unit configured to store a list of specification information of external devices that are incompatible with the host device when data communication is carried out using the high-speed communication mode and a specification information obtainment unit configured to obtain external device specification information from the external device. A device determination unit is configured to determine if the external device specification information obtained from the external device corresponds to an incompatible external device based on the stored specification information and a communication speed control unit sets a data communication speed to the low-speed communication mode if the device determination unit determines that the external device in incompatible with the host device.