Single Channel Bus Device Presence Detection
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Solution Overview
Problem
The existing methods for detecting device presence on a bus require additional dedicated pins, increasing manufacturing costs and reducing circuit design density and complexity.
Innovation Solution
A method and system that utilize a single channel or circuit line to detect device presence by transmitting a signal causing each device to hold the channel to a unique logical state for a specific duration, allowing the controller to identify devices based on the longest duration, eliminating the need for multiple dedicated pins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dedicated pins are used for device presence detection, then device presence can be accurately detected, but manufacturing cost increases and circuit design density decreases
Solution Approach 1:
The patent merges the device presence detection function with the existing I2C bus data line (SDA). Instead of using a separate dedicated pin, the invention utilizes the bidirectional nature of the SDA line to carry both data communication signals and presence detection signals, thereby eliminating the need for additional pins and improving circuit design density while maintaining detection accuracy
Solution Approach 2:
The invention makes the existing SDA line multi-functional by enabling it to serve both its original purpose of data transmission and the additional function of device presence detection. The controller can distinguish between data signals and presence detection responses through timing and signal characteristics, allowing one pin to perform multiple roles
2Reliability
If dedicated pins are used for device presence detection, then device presence can be accurately detected, but manufacturing cost increases
Solution Approach 1:
The patent combines the presence detection functionality into the existing I2C bus structure, eliminating the need for additional dedicated pins. This reduces the bill of materials (BOM) cost and simplifies manufacturing processes, as fewer pins need to be manufactured, routed, and connected on both the controller and device sides
Solution Approach 2:
By making the SDA line multi-functional, the invention eliminates the need for separate presence detection pins, directly reducing component count and manufacturing complexity. The same hardware infrastructure serves dual purposes, lowering overall system cost
Data Source
AI summary
The presence of devices attached to a bus are detected by a controller of a bus transmitting a signal on a channel of the bus, to cause each device to hold the channel to a first logical state for a duration of time that is unique to each device. The device that holds the channel to the first logical state for the longest duration of time is detected. Detected devices remain idle while undetected devices repeat holding the channel to the first logical state for the duration of time, until detected. All devices are detected when the channel returns to a second logical state.