Backplane Presence Detection via Serial Mode Switching
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Solution Overview
Problem
Existing information handling systems face scalability issues with presence detection due to the limited number of presence detection wires, which becomes a bottleneck as the number of devices on a backplane increases, making it difficult to support architectures with multiple NVMe devices.
Innovation Solution
The system employs a backplane with a presence detection wire and data transmission wires, where a host controller monitors for an indicator to switch between discrete and serial modes, receiving serialized presence detection information and deserializing it for communication with input/output devices, enabling efficient detection of multiple devices on a single conductor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If parallel discrete presence detection wires are used, then presence detection capability is provided, but scalability is limited as the number of devices increases
Solution Approach 1:
The patent combines multiple presence detection signals onto a single shared conductor by encoding device presence information in serialized form. Instead of requiring one dedicated wire per device, the system merges all presence detection functionality into a single communication channel that carries time-multiplexed signals from multiple devices.
Solution Approach 2:
The patent segments the presence detection information into discrete time slots or frames, where each device's presence status is transmitted in a specific time window. This segmentation allows multiple devices to share the same conductor without signal collision, as each device transmits its presence information at designated intervals.
2Quantity of substance
If the number of devices on backplane increases, then system capacity increases, but presence detection scalability deteriorates
Solution Approach 1:
The single presence detection conductor serves multiple functions: it carries presence information from all devices, provides device identification, and enables future expansion. The serialized communication protocol allows the same physical wire to adapt to any number of devices by dynamically allocating time slots, making the system universally applicable regardless of device count.
3Adaptability or versatility
If serialized presence detection is implemented, then scalability is improved, but signal processing complexity increases
Solution Approach 1:
The patent introduces an intermediary controller or bridge device that manages the serialized presence detection communication. This intermediary handles the complex tasks of signal demultiplexing, time slot allocation, and device identification, while presenting simplified presence detection interfaces to both the host system and individual devices, thereby distributing and reducing overall system complexity.
Data Source
AI summary
A method may include, in an information handling system having a backplane comprising a plurality of connectors, each connector configured to receive an input/output device, and a motherboard communicatively coupled to the backplane via a cable having a presence detection wire configured to transmit presence detection information associated with the plurality of connectors and further having a plurality of data transmission wires: during a discrete mode, monitoring for an indicator from the backplane via the presence detection wire to determine if the backplane is configured for communication of serial presence detection information regarding the plurality of connectors and enter a serial mode in response to receiving the indicator; during the serial mode, receiving via the presence detection wire serialized frames including serialized presence detection information regarding input/output devices received in the plurality of connectors; and deserializing the serialized presence detection information and communicating deserialized presence detection information to a host controller configured to communicate with input/output devices received in the plurality of connectors via the plurality of data transmission wires.