Serial Bus Subscriber Station Dual Checksum Error Detection
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Solution Overview
Problem
Current serial bus systems, such as CAN FD, face challenges in detecting errors related to dynamic stuff bits, particularly Class 3 and Class 4 errors, which are not reliably detected by existing CRC calculations, leading to potential data corruption and reduced user data rates due to the need for additional overhead like a 'stuff bit counter'.
Innovation Solution
A subscriber station for a serial bus system that inserts two checksums into the frame, with one calculating dynamic stuff bits and the other focusing on different bits, allowing for reliable detection of Class 3 and Class 4 errors without the need for a 'stuff bit counter', thereby increasing user data rate and reducing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dynamic stuff bits are included in the CRC calculation to detect Class 3 errors, then error detection capability is improved, but device complexity increases due to the need for a stuff bit counter
Solution Approach 1:
The patent divides the error detection mechanism into two independent checksums: one that includes dynamic stuff bits and one that excludes them. This segmentation allows each checksum to handle specific error classes independently, eliminating the need for a stuff bit counter while maintaining comprehensive error detection capability.
Solution Approach 2:
The patent extracts the dynamic stuff bits from the CRC calculation by providing two separate checksum options. One checksum calculates over all bits including dynamic stuff bits, while the other calculates only over non-dynamic stuff bits. This extraction eliminates the complexity of tracking stuff bits while preserving error detection capability.
2Reliability
If a stuff bit counter is added to detect Class 4 errors, then error detection capability is improved, but user data rate decreases due to increased overhead
Solution Approach 1:
The patent segments the error detection function into two independent checksums that can be selectively applied. This eliminates the need for a stuff bit counter field, thereby reducing overhead and increasing the effective user data rate while maintaining the ability to detect both Class 3 and Class 4 errors.
3Device complexity
If only one checksum is used in the frame, then frame structure is simplified, but Class 3 and Class 4 errors cannot be reliably detected
Solution Approach 1:
The patent applies segmentation by implementing two independent checksums that cover different aspects of error detection. One checksum detects errors in the header and arbitration fields, while the other detects errors in the data field. This segmentation enables comprehensive error detection without requiring complex integrated verification mechanisms.
Data Source
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Figure 2
Figure 3~5
AI summary
The invention relates to a subscriber station (10; 30) for a serial bus system (1) and to a method for a communication in a serial bus system (1). The subscriber station (10; 30) has a communication controller (11; 31) for controlling a communication between the subscriber station (10; 30) and at least one other subscriber station (10; 20; 30) of the bus system (1) and a transceiver (12; 32) which is designed to serially transmit a transmission signal (TXD) generated by the communication controller (11; 31) to a bus (40) of the bus system (1) and to serially receive signals from the bus (40) of the bus system (1). The communication controller (11; 31) is designed to generate the transmission signal (TXD) according to a frame (450; 450_1; 450_2) and insert two checksums (HCRC, FCRC) into the frame (450; 450_1; 450_2), said checksums calculating different bits of the frame (450; 450_1; 450_2), insert dynamic stuff bits into the frame (450; 450_1; 450_2) such that an inverse stuff bit is inserted into the bitstream of the frame (450; 450_1; 450_2) after 5 identical bits in a row, and calculate the two checksums (HCRC, FCRC) such that the dynamic stuff bits are calculated by maximally one of the two checksums (HCRC, FCRC).