CAN Bus Frame Extension for Flexible Payload and CRC Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current serial data transmission protocols, such as CAN, face challenges in handling increased data volumes and latency requirements in modern vehicle networking, particularly for systems like driving dynamics control and driver assistance systems, while maintaining real-time performance and error detection reliability.
Innovation Solution
The method modifies the CAN protocol by expanding the control field to include additional bits for error passive status and data length code interpretation, allowing for flexible data field sizes and bit lengths, and using parallel CRC calculations with different generator polynomials to enhance error detection and transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the control field is expanded to include additional bits for error passive status and data length code, then the data transmission flexibility and error detection capability are improved, but the message structure complexity increases
Solution Approach 1:
The control field is segmented into standard bits and additional bits, where additional bits serve specific functions (error passive status, data length code interpretation) while standard bits maintain original CAN protocol functions. This segmentation allows flexibility enhancement without completely redesigning the message structure.
Solution Approach 2:
The additional bits in the control field serve multiple functions: indicating error passive status, modifying data length code interpretation, and enabling flexible data field sizes. This multi-functionality achieves transmission flexibility without adding separate dedicated fields for each function.
2Reliability
If parallel CRC calculations with different generator polynomials are implemented, then error detection reliability is improved, but the processing complexity increases
Solution Approach 1:
Multiple CRC calculations are performed in parallel during the reception process, with results stored for later comparison. This preliminary action ensures that error detection is comprehensive before making any transmission validation decisions.
Solution Approach 2:
The received CRC field is compared against multiple calculated CRC values using different generator polynomials. This feedback mechanism provides robust error detection by verifying data integrity through multiple independent checksum validations.
3Quantity of substance
If the data field size is made flexible based on data length code interpretation, then the data volume capacity is improved, but the compatibility with standard CAN systems decreases
Solution Approach 1:
The data length code interpretation is modified locally through additional control field bits, allowing flexible data field sizes (beyond the standard 8 bytes) while maintaining the original CAN protocol structure for standard-length messages. This local modification enables enhanced data capacity without affecting standard CAN compatibility for conventional message types.
Data Source
Figure 1a~1b
Figure 2
Figure 3
AI summary
The invention relates to a method for serial data transmission in a bus system having at least two bus nodes, which exchange messages by means of the bus. The sent messages have a logical structure as per CAN standard ISO 11898-1. The logical structure comprises a start-of-frame bit, an arbitration field, a control field, a data field, a CRC field, an acknowledge field, and an end-of-frame sequence. The control field comprises a data length code, which contains information about the length of the data field. The method is characterized in that the control field of the messages comprises more than six bits, in deviation from CAN standard ISO 11898-1, if a first marker (EDL) is present, at least one additional bit (ESI) being added to the control field of the message if the first marker (EDL) is present, and information about the "error passive" state of the bus node being integrated into sent frames by means of the additional bit (ESI) or one of the additional bits.