CAN Bus Auto-Addressing for Daisy-Chained Satellite Modules
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Solution Overview
Problem
Current methods for assigning network bus addresses to satellite modules in automobiles require dedicated Local Interconnect Network (LIN) PHYs, increasing system cost and complexity.
Innovation Solution
A scheme for auto-addressing satellite modules on a communication bus, such as CAN, without the need for a separate bus like LIN, using a daisy-chained 12-volt battery level signal to wake each satellite module and assign a unique CAN bus address.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If dedicated LIN PHYs are used for auto-addressing satellite modules, then address assignment can be accomplished, but system cost and complexity increase
Solution Approach 1:
The patent merges the auto-addressing function with the existing CAN bus infrastructure by using the same physical communication medium for both data transmission and address assignment. The central module transmits address information embedded within normal CAN bus communication frames, eliminating the need for separate LIN PHY hardware dedicated to addressing functions.
Solution Approach 2:
The CAN bus is made multi-functional by enabling it to serve both its primary purpose of data communication and the secondary purpose of address assignment. The same physical layer and protocol stack handle both operational data traffic and addressing information, making the communication infrastructure universal rather than requiring dedicated addressing hardware.
2Ease of manufacture
If dedicated LIN PHYs are used for auto-addressing satellite modules, then address assignment can be accomplished, but system cost increases
Solution Approach 1:
The patent combines multiple functions (data communication and address assignment) into a single communication channel, reducing the total quantity of hardware components required. By embedding address information in existing CAN bus frames rather than using separate LIN PHYs, the system eliminates redundant hardware and reduces component count.
Solution Approach 2:
The patent extracts the address assignment function from the dedicated LIN PHY hardware and integrates it into the software/protocol layer of the existing CAN bus system. This extraction eliminates the need for separate addressing hardware while maintaining the addressing capability.
3Ease of manufacture
If a single hardware board design is used for all satellite modules, then inventory cost and manufacturing complexity are reduced, but a new addressing scheme is required
Solution Approach 1:
The patent implements a self-service addressing mechanism where satellite modules automatically receive their addresses through the CAN bus communication protocol. The central module assigns addresses dynamically during system initialization or upon module connection, eliminating the need for manual address configuration or pre-programming on each hardware board.
Solution Approach 2:
The addressing scheme performs preliminary address assignment during system startup or module initialization before normal operational communication begins. This preliminary action ensures all modules have unique addresses configured and ready for use without requiring manual intervention or complex post-installation configuration.
Data Source
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AI summary
An apparatus for auto addressing nodes on a communication bus comprising a central module (310) having a power converter (316), an MCU (322), a communication bus physical layer (PHY) (318), and a central module low side switch (320). The apparatus also includes a first satellite module (340) having a power converter (336), a first satellite MCU (338) having a general purpose input and output (354) and a communication port, a first satellite communication bus PHY (342), and a low side switch (350). The apparatus further includes a second satellite module (370) having a power converter (366), a second satellite MCU (368), a second satellite communication bus PHY (372) coupled to the second satellite MCU (368).