Hot-Plug Link Apparatus Using Direction Line for Presence Detection
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Solution Overview
Problem
Current hot-plug technologies require complex and costly back-plane designs due to the need for numerous side-band signals in blade server environments, which complicates and expenses mid-plane or back-plane design for connecting multiple hosts and hot-plug devices.
Innovation Solution
A system utilizing a master and slave interface circuit with a direction line, data line, and clock line to communicate and synchronize data, where the direction line also conveys Presence Detect signals, reducing the need for a separate Presence Detect line and combining multiple signals onto a single data line, thereby simplifying the connection and reducing the number of physical lines required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple separate lines are used for Presence Detect signals and data signals in hot-plug connections, then signal integrity and reliability are improved, but device complexity and manufacturing cost increase due to complex back-plane design
Solution Approach 1:
The patent combines multiple separate signal lines (Presence Detect and data signals) into a single bidirectional data line. The presence detect function is integrated by using signal transitions on the data line itself to indicate device presence, eliminating the need for separate Presence Detect lines and reducing back-plane complexity.
Solution Approach 2:
The data line serves multiple functions: it transmits data bidirectionally and simultaneously indicates device presence through signal transitions. This multi-functional approach replaces dedicated Presence Detect lines, reducing the number of physical connections required in the back-plane while maintaining reliable detection capabilities.
2Adaptability or versatility
If numerous side-band signals are routed through the mid-plane for PCIe connectivity, then hot-plug functionality is achieved, but manufacturing cost and design complexity increase
Solution Approach 1:
The patent merges multiple side-band signal functions into a single bidirectional data line that handles both data transmission and presence detection. This consolidation reduces the number of signal routes required through the mid-plane, simplifying manufacturing while preserving complete hot-plug functionality.
Solution Approach 2:
The presence detection capability is extracted from separate dedicated lines and integrated into the existing data line communication protocol. By detecting presence through data line signal transitions rather than separate lines, the patent eliminates redundant signal routing through the mid-plane, reducing manufacturing complexity.
3Measurement precision
If separate Presence Detect lines are used for each hot-plug device connection, then device presence detection is reliable, but the number of physical lines increases
Solution Approach 1:
The data line performs dual functions: transmitting data and detecting device presence. Presence is detected by monitoring signal transitions on the data line when devices are connected or disconnected, eliminating the need for separate Presence Detect lines while maintaining accurate detection capability.
Solution Approach 2:
The patent combines presence detection functionality with data transmission on the same physical line. By using the data line's signal characteristics to indicate presence, the patent reduces the total number of physical lines required while preserving reliable presence detection for each hot-plug device.
Data Source
AI summary
An apparatus for linking a hot-plug device to a host includes a slave interface circuit for connection to the host; a master interface circuit for connection to the hot-plug device; and direction, data, and clock lines that link the master and slave interface circuits. A control logic circuit detects a Presence Detect signal on the direction line. A method of determining a connection between a host and a hot-plug device includes asserting a direction signal on a direction line to control a direction of a flow of data between the host and the hot-plug device; toggling the direction signal to indicate a presence of the hot-plug device; and indicating a disconnect after a given period of inactivity in the toggling. A method of linking a host and a hot-plug device interface circuit for connection to a hot-plug device includes asserting a Presence Detect signal on the direction line.