Hub Device Ring Topology for USB Enumeration Speed
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Solution Overview
Problem
Conventional methods for selecting device identifiers in non-volatile memory devices, such as USB flash memory and removable memory cards, are inefficient, requiring multiple identifier transmissions and duplicating identifier values, leading to increased enumeration time as the number of devices increases.
Innovation Solution
A hub device is configured to emulate a ring communication topology, allowing devices to select distinctive identifier values by serially propagating enumeration messages, enabling each device to determine an identifier value that is distinct from previously used values, thereby reducing the need for additional identifier transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional sequential identifier transmission method is used, then devices can be enumerated, but the enumeration time increases significantly as the number of devices increases
Solution Approach 1:
The hub device performs preliminary actions by pre-configuring a table of used identifier values and proactively transmitting enumeration messages to all devices in the network before the actual enumeration process begins. This allows devices to pre-select their identifiers based on the pre-shared used values table, eliminating the need for sequential trial-and-error identifier transmission during enumeration.
Solution Approach 2:
The hub device acts as an intermediary that facilitates efficient identifier selection by maintaining a central table of used identifier values and distributing this information to all devices. The hub mediates the enumeration process by coordinating the serial propagation of enumeration messages and collecting responses, thereby enabling parallel identifier selection across multiple devices without time-consuming sequential transmissions.
2Extent of automation
If devices increment identifier values by pre-set amounts, then identifier selection is automated, but identifier duplication occurs and additional transmissions are required
Solution Approach 1:
The system implements feedback mechanisms where devices receive enumeration messages containing information about used identifier values from the hub and other devices. Each device uses this feedback to adjust its identifier selection, ensuring that selected identifiers are unique and not already in use. The hub collects and processes feedback responses to coordinate the enumeration process and prevent duplications.
Solution Approach 2:
The hub device creates a copy of the used identifier values table and distributes this copy to all devices in the network. This copied information allows each device to independently select unique identifiers without real-time coordination, eliminating the need for sequential transmissions while ensuring identifier uniqueness across all devices.
3Reliability
If multiple sequential identifier transmissions are performed, then unique identifiers can be assigned, but the number of transmissions increases with the number of devices
Solution Approach 1:
The enumeration process is segmented into distinct phases: the hub device first transmits used identifier values to all devices, then devices independently select their identifiers in parallel, and finally devices transmit their selected identifiers back to the hub for validation. This segmentation allows multiple devices to operate simultaneously without increasing the overall transmission complexity.
Solution Approach 2:
The enumeration message serves multiple functions: it conveys used identifier values, triggers identifier selection, and coordinates the enumeration process. By making the message multi-functional, the system reduces the number of separate transmission protocols needed, maintaining simplicity while achieving reliable unique identifier assignment across multiple devices.
Data Source
AI summary
Systems and methods of device identifier selection are disclosed. In a particular embodiment, a method includes, at a hub device having a plurality of ports including a first port, a second port, and a third port, receiving a first message from a host device. The first message including a broadcast indicator. The method also includes, in response to determining that the first message requests enumeration, emulating a ring communication topology by serially propagating messages including an enumeration indicator to a first device via the first port and to a second device via the second port. The method further includes, in response to determining that the first message does not request enumeration, selectively sending the first message to the first device substantially concurrently with sending the first message to the second device. Emulating the ring communication topology enables the hub device to provide a first distinctive identifier value of the first device and a second distinctive identifier value of the second device to the host device.