Serial Bus User Station Format Switchover Mechanism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing CAN FD bus system has a slow data transfer rate during the arbitration phase due to the use of the same physical layer for both arbitration and data transfer, limiting the overall data transfer rate and security of data transmission.
Innovation Solution
A user station for a serial bus system that includes a communication control device and a format switchover checking unit, allowing for a switch from a first communication phase to a second phase with a different physical layer and bit rate, enabling error-robust communication and increased data transfer rates by using error frames and specific bit sequences for format switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the same physical layer is used for both arbitration and data transfer in CAN FD, then arbitration security is maintained, but data transfer rate is limited
Solution Approach 1:
The communication process is divided into two distinct phases: arbitration phase using the first physical layer (CAN FD) to maintain security and collision-free access, and data transfer phase using the second physical layer (CAN NG) to achieve higher data rates. This segmentation allows each phase to optimize for its specific requirements without compromise.
Solution Approach 2:
The system dynamically switches between two different physical layers depending on the communication phase. The transceiver device is configured to use the first physical layer during arbitration and the second physical layer during data transfer, allowing the system to adapt its characteristics to match the requirements of each phase.
2Productivity
If a different physical layer is used for data transfer to increase bit rate, then data transfer speed improves, but format switchover errors may occur
Solution Approach 1:
The format switchover is initiated in advance during the arbitration phase by setting specific bits (FDF bit and res bit) in the message frame. This preliminary action allows all user stations to prepare for the upcoming physical layer change before the actual data transfer begins, ensuring synchronized and error-free switching.
Solution Approach 2:
The system uses feedback mechanisms through specific bit sequences (FDF, res, res2, res3, res4 bits) that indicate the format switchover status. User stations monitor these bits to confirm whether the switchover was successful and to detect any errors, allowing for error detection and correction.
3Device complexity
If format switchover is implemented without error detection, then device complexity is reduced, but communication reliability decreases
Solution Approach 1:
The format switchover mechanism incorporates feedback through check bit sequences (res2, res3, res4 bits) that allow user stations to verify whether the switchover was successful. This feedback enables error detection and reporting without significantly increasing device complexity, maintaining a balance between simplicity and reliability.
Solution Approach 2:
The system uses parameter changes in the message format (specific bit sequences) to indicate and verify the physical layer switchover. By encoding switchover information in existing message parameters rather than adding separate control mechanisms, the solution maintains simplicity while ensuring reliable error detection.
Data Source
AI summary
A user station is described. The user station includes a communication control device for transmitting and/or receiving messages to/from a bus of a serial bus system, a format switchover checking unit for checking whether the communication control devices of the bus system have switched over the format of the messages from a first format in a first communication phase to a second format for a second communication phase, and a transceiver device which, for transmitting in the first format, generates a first bus state for a first digital data state of the messages and a second bus state for the second digital data state of the messages so that the second bus state can overwrite the first bus state. The transceiver device, for transmitting in the second format, generates different bus states so that the bus states for the different digital data states of the messages cannot overwrite one another.