CAN Controller Module for High-Rate Frame-Start Detection
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Solution Overview
Problem
In large CAN systems, bit corruption occurs due to delayed detection of frame starts at distant nodes, leading to overlapping frame transmissions and signal distortion, particularly when high data rates are maintained.
Innovation Solution
A CAN module with a CAN controller configured to detect the end of an idle state, sample bit values at specific intervals, and adjust bit values to handle dominant signal levels, ensuring accurate frame reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high data rates are maintained in large CAN systems, then transmission speed is improved, but bit corruption occurs due to delayed frame start detection at distant nodes
Solution Approach 1:
The patent applies preliminary action by detecting the end of the idle state before the actual frame transmission begins. By setting a reference time at the end of the idle state and calculating sample times based on this reference, the system proactively prepares for frame arrival, allowing distant nodes to synchronize their sampling before corruption occurs during high-speed transmission
Solution Approach 2:
The patent uses the reference time and calculated sample times as intermediaries between the frame start event and the actual sampling process. This intermediary timing mechanism allows nodes to bridge the detection delay inherent in large CAN systems, enabling accurate bit sampling even when frame starts are detected late at distant nodes
2Device complexity
If sampling is performed at fixed intervals without adjustment, then device complexity is reduced, but bit corruption occurs when dominant signal levels extend beyond expected intervals
Solution Approach 1:
The patent applies dynamics by making the sampling mechanism adaptive rather than fixed. The sample times are dynamically calculated based on the detected end of idle state and the predefined reference time interval. Additionally, the system dynamically adjusts by discarding sampled bits that represent dominant signal levels and replacing them with correctly identified start bits, allowing the sampling process to adapt to varying signal conditions
Solution Approach 2:
The patent changes the timing parameters dynamically by calculating sample times as offsets from the reference time (e.g., first sample time = reference time + 0.6×reference time interval). This parameter adjustment ensures that sampling occurs at optimal moments relative to frame starts, preventing corruption while maintaining manageable device complexity
3Area of stationary object
If frame start detection is delayed at distant nodes, then network coverage area is improved, but overlapping frame transmissions occur causing signal distortion
Solution Approach 1:
By detecting the end of the idle state and establishing a reference time before frames are transmitted, the system performs preliminary synchronization. This allows distant nodes to prepare their sampling schedules in advance, ensuring they are ready to capture frame starts accurately even though they are located far from the transmission source
Solution Approach 2:
The system uses feedback by monitoring the RXD signal for the end of idle state and using this detection to adjust subsequent sampling times. This feedback mechanism ensures that each node independently synchronizes to actual frame starts on the bus, preventing overlapping transmission issues even in large networks with significant propagation delays
Data Source
AI summary
The present disclosure relates to a CAN controller module. The CAN controller module is configured to detect transmission errors during transmissions of bits of a CAN frame via a CAN but and to handle these transmission errors robustly such that a high transmission rate is possible even if the transmission errors occur. The present disclosure also relates to a method for the CAN controller module.