CAN Frame Decoder Using RX/TX Bitstream Merging
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Solution Overview
Problem
Existing CAN protocol decoders struggle to accurately decode CAN frames due to distortions on the bus, leading to difficulties in identifying start-of-frame bits and synchronization issues, which can result in erroneous frame format conclusions and compromised safety or security monitoring.
Innovation Solution
An apparatus and method that includes a CAN protocol decoder and circuitry to detect idle states between frames, modifying the bitstream to include missing start-of-frame bits based on the RX-bitstream, and combining RX-bitstream and TX-bitstream for accurate decoding, with compliance checking to ensure adherence to CAN protocol rules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the CAN protocol decoder uses the TX-bitstream for decoding CAN frames, then the monitoring of CAN controller is simplified, but the decoding accuracy deteriorates due to distortions on the bus and missing start-of-frame bits
Solution Approach 1:
The patent combines the RX-bitstream and TX-bitstream into a unified decoded bitstream that is fed to the CAN protocol decoder. The circuitry merges signals from both the received RX-bitstream and the generated TX-bitstream, ensuring that the decoder receives a complete and accurate bitstream that includes start-of-frame bits even when distortions occur on the bus. This merging approach resolves the contradiction by maintaining decoding accuracy while preserving monitoring simplicity.
Solution Approach 2:
The patent introduces an intermediary circuitry component that processes both the RX-bitstream and TX-bitstream before delivering the final decoded signal to the CAN protocol decoder. This intermediary layer reconstructs missing start-of-frame bits and compensates for bus distortions, acting as a mediator that ensures accurate decoding without complicating the overall monitoring process.
2Measurement precision
If the circuitry modifies the bitstream to include start-of-frame bits based on RX-bitstream, then the decoding accuracy is improved, but the device complexity increases
Solution Approach 1:
The circuitry is designed with multi-functionality, serving multiple purposes: it processes the RX-bitstream, generates the TX-bitstream, detects idle states, reconstructs missing start-of-frame bits, and prepares the final decoded signal for the CAN protocol decoder. By making the circuitry universal and multi-functional, the patent improves decoding accuracy without proportionally increasing device complexity, as a single circuitry block performs multiple essential functions.
3Reliability
If the apparatus combines RX-bitstream and TX-bitstream for decoding, then the reliability of CAN frame decoding is improved, but the processing time increases
Solution Approach 1:
The circuitry performs preliminary processing by continuously monitoring for idle states and pre-reconstructing missing start-of-frame bits before the CAN protocol decoder needs to process the full frame. This preliminary action ensures that when the decoder operates, it receives a complete and reliable bitstream, improving decoding reliability while minimizing the time penalty by doing the heavy lifting in advance.
Data Source
AI summary
An apparatus for a controller area network, CAN, node, the node comprising a CAN controller and a CAN transceiver that is configured to couple to a CAN bus, the apparatus comprising a CAN protocol decoder and circuitry, the apparatus configured to:receive an RX-bitstream generated by the CAN transceiver for the CAN controller;receive a TX-bitstream generated by the CAN controller for receipt by the CAN transceiver;wherein the CAN protocol decoder is configured to receive a bitstream based on the TX-bitstream for decoding CAN frames therein for monitoring of the CAN controller; and wherein the circuitry is configured to:detect an idle state;based on the detection of the idle state, modify the bitstream received by the CAN protocol decoder such that it includes a Start-of-Frame bit further based on detection of a Start-of-frame bit in the RX-bitstream.