CAN Bus Frame Extension for Flexible Payload and Dual CRC
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing CAN bus systems face limitations in data transfer capacity and reliability due to fixed message structures and bit lengths, which are inadequate for the increasing data volumes and latency demands in modern vehicle networking applications.
Innovation Solution
The method modifies the CAN bus message structure by expanding the control field to include additional bits for error passive state indication and data length code interpretation, allowing for flexible data field sizes and bit lengths, and uses dual CRC calculations with different generator polynomials for enhanced fault detection and data transfer efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the CAN bus message structure uses fixed data field sizes (maximum 8 bytes), then compatibility with standard CAN systems is maintained, but data transfer capacity is limited
Solution Approach 1:
The patent implements dynamic message structures where the data field size can vary beyond the standard 8-byte limit. This is achieved through extended message formats that allow flexible data lengths while maintaining backward compatibility with standard CAN systems, directly resolving the contradiction between fixed structure constraints and data transfer capacity requirements
Solution Approach 2:
The patent changes the parameters of the message structure by introducing extended data field sizes and variable bit lengths. By modifying the message format parameters (allowing data fields larger than 8 bytes and variable bit lengths), the system achieves higher data transfer volumes while maintaining compatibility through selective parameter usage
2Reliability
If additional bits are added to the control field for error passive state indication, then reliability is improved, but message structure complexity increases
Solution Approach 1:
The patent merges the error passive state indication function with the existing control field structure. By integrating additional functionality (error state indication) into the already-present control field without creating a separate mechanism, the patent improves reliability while minimizing the increase in structural complexity
Solution Approach 2:
The control field is designed to serve multiple functions: traditional control operations plus error passive state indication. This multi-functionality approach allows the same field to handle both standard control tasks and error state communication, improving reliability without proportionally increasing complexity
3Productivity
If variable bit lengths are implemented in message regions, then data transfer efficiency is improved, but compatibility with standard CAN protocols is reduced
Solution Approach 1:
The patent applies variable bit lengths locally to specific regions within messages rather than uniformly across all data. This allows efficient data representation in specific areas while maintaining standard formatting in other regions, thereby improving transfer efficiency without completely sacrificing protocol compatibility
Solution Approach 2:
The message structure is segmented into regions with different bit length characteristics. By dividing the message into segments that can have variable bit lengths in certain regions while maintaining standard lengths in others, the patent achieves improved efficiency in critical areas while preserving compatibility in standardized regions
4Reliability
If dual CRC calculations with different generator polynomials are used, then fault detection reliability is improved, but processing complexity increases
Solution Approach 1:
The patent performs preliminary CRC calculations using different generator polynomials during the data transmission process. By pre-calculating and verifying data integrity with multiple polynomial methods before final acceptance, the system improves fault detection reliability while managing processing complexity through structured computation
Data Source
AI summary
A method for serial data transfer in a bus system having at least two bus subscribers that exchange messages via the bus, the transmitted messages having a logical structure according to CAN standard ISO 11898-1, the logical structure encompassing a start-of-frame bit, arbitration field, control field, data field, CRC field, acknowledge field, and end-of-frame sequence, the control field encompassing a data length code having an information item regarding the data field length. When a first marker (EDL) is present, the control field of the messages, divergently from the CAN standard ISO 11898-1, encompasses more than six bits; when the first marker (EDL) is present, the control field of the message is expanded to include at least one further bit (ESI); and the further bit (ESI) or one of the further bits causes an information item regarding the “error passive” state of the bus subscriber to be integrated into transmitted messages.