CAN System Error Data Generation via Protocol Processing
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Solution Overview
Problem
Conventional CAN systems face challenges in accurately evaluating communication quality, especially at higher communication rates like 1 Mbps, and cannot effectively test error management circuits in loop back mode due to limitations in generating error data and hardware constraints.
Innovation Solution
A CAN system that incorporates error data into receive or send data within the electric control units using a protocol processing part, register, and error management circuit, allowing for error data generation and communication quality evaluation without external hardware, and enabling error detection testing in loop back mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external hardware is used to generate error data on the communication bus, then error data generation is possible, but the system cannot accurately generate error data at higher communication rates like 1 Mbps due to hardware limitations
Solution Approach 1:
The ECU performs self-diagnosis by generating error data internally within its own communication interface. The protocol processing part incorporates error data into send data, which then passes through the transceiver onto the bus and back to the same ECU. This self-service approach eliminates the need for external error generation hardware and enables testing at any communication rate supported by the ECU itself.
Solution Approach 2:
The transceiver acts as an intermediary that carries send data from the ECU onto the communication bus and returns receive data from the bus to the ECU. This intermediary mechanism enables the error data to traverse the external bus environment without requiring external error generation hardware, allowing accurate error data generation at high communication rates.
2Reliability
If loop back mode is used for self-diagnosis, then circuit defects in normal communication can be checked, but error management circuit defects cannot be detected because loop back mode assumes normal communication without error data
Solution Approach 1:
The protocol processing part dynamically switches between normal mode and test mode. In test mode, it incorporates error data into send data while in normal mode it processes data without errors. This dynamic capability allows the same loop back path to serve both normal communication testing and error management circuit testing, enhancing versatility without compromising reliability.
Solution Approach 2:
The system changes the parameter of the communication data by incorporating error data into send data during test mode. This parameter change transforms normal communication data into error-containing data, enabling the error management circuit to be tested through the same loop back mode that normally assumes error-free communication.
3Ease of operation
If conventional hardware is used for error data generation, then error data can be generated on the bus, but the insert timing of error data is delayed and communication rate compatibility is limited to 125 kbps or lower
Solution Approach 1:
The ECU generates error data internally using its own protocol processing part, eliminating the need for external hardware that introduces timing delays. The error data is incorporated into send data at the source before transmission, ensuring precise timing control and enabling operation at high communication rates up to 1 Mbps and beyond.
Data Source
AI summary
Provided is a CAN system that can generate an error signal without requiring hardware for generating an error signal to be connected to a bus. A protocol processing part within a CAN controller incorporates error data into receive data or send data, based on error data information stored in a register.