USB Composite Device Logic Interface Merging
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Solution Overview
Problem
The increasing number of logic interfaces required to connect devices with different USB classes and subclasses in a composite machine leads to higher costs and circuit size requirements for the device controller, as each combination necessitates a separate logic interface.
Innovation Solution
Assigning devices with different USB subclasses to the same logic interface, where logic interface information is sent to the host to identify logical units, allowing communication using commands specific to each device's subclass, thereby reducing the need for multiple logic interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate logic interfaces are assigned to each device combination of USB class and USB subclass, then device identification and communication control are improved, but the number of logic interfaces increases leading to higher costs and larger circuit size
Solution Approach 1:
The patent merges multiple logic interfaces into a single shared logic interface. Devices with different USB subclasses (e.g., SCSI and ATAPI) that previously required separate logic interfaces are now assigned to the same shared logic interface, reducing the total number of interfaces while maintaining proper device identification through subclass-specific communication commands
Solution Approach 2:
The shared logic interface is designed to handle multiple USB subclasses universally. Instead of having dedicated interfaces for each subclass, a single logic interface can communicate with devices of different subclasses by adapting its communication commands based on the device's USB subclass, making the interface multi-functional
2Adaptability or versatility
If the number of logic interfaces is increased to support devices with different USB subclasses, then communication compatibility is improved, but circuit size and manufacturing costs increase
Solution Approach 1:
The logic interface is designed with universal capability to communicate with multiple USB subclasses (SCSI, ATAPI, and others). The interface adapts its communication commands based on the device's USB subclass information, eliminating the need for multiple dedicated interfaces and thereby reducing manufacturing costs while maintaining broad compatibility
3Reliability
If separate logic interfaces are assigned to devices with the same USB class but different USB subclasses, then command-specific communication is improved, but the device controller's circuit size increases
Solution Approach 1:
The patent combines multiple logic interfaces into a single shared interface that can reliably communicate with devices of different USB subclasses. The interface determines the appropriate communication commands based on the device's USB subclass, ensuring reliable communication without requiring separate dedicated interfaces for each subclass
Data Source
AI summary
A USB composite device including devices of different USB subclasses and enable communications between the devices and a host without increasing the number of logic interfaces, comprising a first device having a first USB subclass and a second device having a second USB subclass corresponding to a second communication command are assigned as devices of the same USB subclass to the same logic interface, and logic interface information that associates the same logic interface with the same USB subclass and the number of logical units are sent to the host. The first and second devices send back device information to the host for each logical unit in response to an inquiry about the device information from the host with the same communication command, and the host performs communications with the communication command supported by each device.