Shared Bus Driver Mode Switching for CAN Bandwidth and Compatibility
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Solution Overview
Problem
The challenge of achieving increased data bandwidth in CAN-bus protocols while maintaining backwards compatibility and addressing issues with non-ideal network topologies, which limit the maximum bus speed and data transmission efficiency.
Innovation Solution
The implementation of an enhanced driver mode for a shared bus that actively drives signal levels, using a combination of passive and active driver circuits to manage signal transitions and impedance, allowing for higher data rates while maintaining compatibility with existing devices and protocols, and incorporating a dedicated CANFD transceiver to improve electromagnetic compatibility and data bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If passive bias is used to set the signal bus to recessive value, then backwards compatibility with existing CAN-bus protocols is maintained, but data bandwidth and transmission speed are limited
Solution Approach 1:
The system dynamically switches between two driver circuit configurations: a first driver circuit for standard CAN mode using passive bias, and a second driver circuit for enhanced mode using active driving. The control circuit activates the appropriate driver circuit based on the transmission mode, enabling the system to adapt its electrical characteristics in real-time to achieve both compatibility and high bandwidth
Solution Approach 2:
The patent changes the electrical parameters of the bus interface by switching between passive bias (standard CAN) and active driving (enhanced mode). The second driver circuit actively drives the bus to both dominant and recessive levels, fundamentally changing the electrical characteristics to enable higher data rates while the control circuit manages the parameter transition
2Productivity
If active driving to recessive level is implemented, then data bandwidth is increased, but compatibility with standard CAN-bus devices is compromised
Solution Approach 1:
The system uses a control circuit to dynamically select between two driver circuits based on the transmission mode. During arbitration mode, the first driver circuit (passive bias) is used to maintain compatibility. During high-speed data transmission, the second driver circuit (active driving) is activated to achieve enhanced bandwidth, thus dynamically adapting to different operational requirements
3Productivity
If higher data rates are achieved, then transmission efficiency is improved, but electromagnetic compatibility issues arise
Solution Approach 1:
The second driver circuit acts as an intermediary that provides controlled active driving to recessive levels during high-speed transmission. This intermediary structure allows the system to achieve higher data rates while managing electromagnetic emissions through controlled signal transitions, bridging the gap between high-speed performance and electromagnetic compatibility
Data Source
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AI summary
A device (102) includes a transmission circuit that is configured and arranged to transmit data in accordance with a signal bus protocol that uses passive bias (114) to set a signal bus to a recessive value in the absence of an actively-driven signal value. The transmission circuit includes a first driver circuit (108,110) that is configured and arranged to actively drive the signal bus to a dominant value that is different from the recessive value. The transmission circuit also includes a second driver circuit (106,112) that is configured and arranged to actively drive the signal bus to the recessive value. A control circuit (104) is configured and arranged to disable the second driver circuit (106,112) in response to the device operating in a first data transmission mode, and to enable the second driver circuit (106,112) in response to the device entering a second transmission mode.