Resistor Network for Card Edge Connector Configuration Detection
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Solution Overview
Problem
The existing method of using I2C bus communication lines to detect card edge connector configurations in computer systems is becoming increasingly expensive and unreliable due to the need for multiple circuit board traces and pins, and is prone to bus hang-ups and boot-up issues.
Innovation Solution
A resistor network is used to provide a signal to a management controller, allowing it to determine the configuration state of card edge connectors by measuring voltage changes based on the presence, type, and sequence of circuit card assemblies, reducing the need for multiple bus communications and pin counts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If I2C bus communication lines are used to detect card edge connector configurations, then detection capability is provided, but the number of circuit board traces and pins increases, and reliability decreases due to bus hang-ups
Solution Approach 1:
Multiple I2C bus communication lines for detecting different card edge connector configurations are merged into a single detection circuit. The system uses one detection circuit that can detect the presence, type, and sequence of multiple circuit card assemblies through shared detection lines, rather than requiring separate I2C bus lines for each connector.
Solution Approach 2:
The detection circuit is designed to perform multiple detection functions using a single circuit. It can detect presence of card assemblies, identify card types, and determine insertion sequences across multiple card edge connectors simultaneously, making the detection system universal rather than dedicated to specific connectors.
2Measurement precision
If multiple I2C bus communication lines are used for each card edge connector, then detection capability is improved, but pin count on management controller increases
Solution Approach 1:
Multiple detection functions are combined into a single detection circuit that shares detection lines across multiple card edge connectors. The system merges the functionality of what would require multiple separate I2C bus connections into one unified detection path, reducing the number of pins needed on the management controller.
Solution Approach 2:
The system transitions from a one-to-one mapping between detection circuits and connectors to a many-to-one relationship. Multiple connectors are detected through a single detection circuit by utilizing the detection capability across different dimensions (multiple connectors, multiple card types, multiple positions) rather than requiring proportional increases in detection circuitry.
3Loss of information
If I2C bus communication is used for card detection, then configuration information can be obtained, but boot-up problems and bus hang-ups occur
Solution Approach 1:
The system replaces the I2C bus communication protocol (which is prone to hang-ups and boot-up issues) with a simpler detection mechanism. Instead of relying on bidirectional digital communication that can deadlock, the system uses a unidirectional detection approach that provides configuration information without the complexity of full I2C protocol handshaking, thereby eliminating bus hang-up problems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces the number of circuit traces and pin counts on the management controller, provides reliable detection of card edge connector configurations, and avoids boot-up problems, enabling efficient and robust identification of installed card assemblies.
Implementation Method 1
A resistor network is used to provide a signal to a management controller, allowing it to determine the configuration state of card edge connectors by measuring voltage changes
Data Source
AI summary
A technique includes coupling a resistor network to a plurality of card edge connectors. The resistor network has a resistance, and each card edge connector includes electrical contacts to couple a resistor of a circuit card assembly, when inserted into the card edge connector, to the resistor network to alter the resistance of the resistor network. The technique includes determining a state of the plurality of card edge connectors based on a signal that is provided by the resistor network.