Time-Stamped CAN Bus Message Bridge for Ethernet
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Controller Area Network (CAN) messages lack time-stamping mechanisms, which are essential for efficient transmission over time-sensitive protocols like Ethernet, as CAN relies on priority schemes and arbitration rather than timestamps for message ordering.
Innovation Solution
A network bridge, such as an Ethernet bridge, generates a time stamp for CAN messages by monitoring the CAN bus for the Start-of-Frame (SOF) and End-of-Frame (EoF) markers, storing the timestamp in a lookup table, and uses this information to schedule transmissions over an Ethernet network, ensuring accurate timing and message prioritization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CAN messages use priority schemes and arbitration for message ordering, then message transmission reliability is improved, but time-stamping capability deteriorates
Solution Approach 1:
The patent introduces an intermediary time-stamping mechanism that operates alongside the existing CAN arbitration system. A timestamp counter is incremented at defined events (such as when a message is received or transmitted), and this timestamp is attached to messages as an additional field. This intermediary time reference does not interfere with the priority-based arbitration but provides the missing time-ordering information needed for time-sensitive protocols like Ethernet.
2Ease of operation
If CAN protocol is used for local device communication, then communication simplicity is improved, but adaptability to time-sensitive networks deteriorates
Solution Approach 1:
The patent makes the CAN protocol multi-functional by adding time-stamping capability that enables it to operate in both traditional priority-based environments and time-sensitive networks. The timestamp field and associated counter mechanism allow CAN messages to carry time-information, making them adaptable to Ethernet AVB (Audio Video Bridging) and other time-critical protocols while preserving the original simple priority arbitration functionality.
3Measurement precision
If time stamps are generated by adding latency to received message time, then timing accuracy is improved, but transmission delay increases
Solution Approach 1:
The patent implements preliminary action by pre-incrementing the timestamp counter at defined events before message transmission. The counter is incremented when a message is received or when transmission begins, so the timestamp is already prepared and attached to the message. This eliminates the need to calculate timestamps in real-time during transmission, reducing actual transmission delay while maintaining accurate timing records.
Data Source
Figure 1
Figure 2~3
AI summary
Systems, methods, and apparatuses are provided herein for time-stamping a Controller Area Network ("CAN") bus message. Control circuitry (e.g., of a network bridge) may receive a CAN message, and may, in response to receiving the CAN message, generate a time stamp. The control circuitry may add an entry to a lookup table stored in memory, wherein the entry correlates a CAN message Identifier ("ID") corresponding to the CAN message with the time stamp. The control circuitry may encapsulate the CAN message and the time stamp, and may transmit the CAN message according to the time stamp.