USB Device Multiplexer Switching Data Paths
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Solution Overview
Problem
Conventional USB devices using bulk-only transmission mode experience performance degradation due to repeated clearing and storing operations in the bulk endpoint buffer, as they rely solely on the bulk endpoint for data transfer, leading to delayed data transmission.
Innovation Solution
The USB device employs both a bulk endpoint buffer and an interrupt endpoint buffer, with a multiplexer to switch data paths between them, allowing common data to be transferred through the bulk endpoint and command-related data (CBW, CSW) through the interrupt endpoint, reducing the frequency of bulk endpoint buffer clearing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only the bulk endpoint is used to transfer data in bulk-only transmission mode, then the USB device structure is simple, but the bulk endpoint buffer requires repeated clearance causing performance degradation
Solution Approach 1:
The patent segments the data transfer function by introducing a second data path through the interrupt endpoint, separating command-related data (CBW/CSW) from common data. This allows the bulk endpoint buffer to be used primarily for common data transfer without repeated clearing operations, while the interrupt endpoint handles command data, thus resolving the performance degradation issue while maintaining relatively simple device structure.
Solution Approach 2:
The patent makes the interrupt endpoint, which is normally idle in bulk-only mode, multi-functional by using it to transfer command-related data (CBW and CSW). This allows the USB device to handle both common data and command data through dedicated paths, improving overall data transmission efficiency without requiring complete abandonment of bulk-only mode simplicity.
2Ease of operation
If the bulk endpoint buffer is repeatedly cleared for storing transmitted and received data, then data can be transferred through a single endpoint, but transmission is delayed and system performance degrades
Solution Approach 1:
The patent segments the data transfer function by introducing a second data path through the interrupt endpoint, separating command-related data (CBW/CSW) from common data. This allows the bulk endpoint buffer to be used primarily for common data transfer without repeated clearing operations, while the interrupt endpoint handles command data, thus resolving the performance degradation issue while maintaining relatively simple device structure.
Solution Approach 2:
The patent performs preliminary action by pre-establishing two distinct data paths (bulk endpoint for common data, interrupt endpoint for command data) before data transfer begins. This preliminary setup prevents the need for repeated buffer clearing during operation, as each endpoint type is dedicated to specific data categories, thereby eliminating transmission delays caused by buffer management overhead.
Data Source
AI summary
A method of Universal Serial Bus (USB) data transfer is provided. In one embodiment, a USB device supports a bulk-only transmission mode to transfer data with a USB host, and the USB device comprises a bulk endpoint buffer storing data transferred between the USB device and the USB host through a bulk endpoint of the USB device and an interrupt endpoint buffer storing data transferred between the USB device and the USB host through an interrupt endpoint of the USB device. A first portion of data stipulated to be transferred through the bulk endpoint is stored with the interrupt endpoint buffer. A data path through which data is transferred between the USB host and the USB device is switched to lead to either the bulk endpoint buffer or the interrupt endpoint buffer with a multiplexer.