CAN Bus ECU Message Validity Detection via Interval Comparison
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Solution Overview
Problem
Conventional communication systems, such as those using the Control Area Network (CAN), struggle to determine the validity of messages transmitted by devices connected via a data link connector, especially when the ignition switch is off or on, and cannot effectively detect invalid messages from user-prepared devices.
Innovation Solution
A communication system where communication devices set and share a defined communication interval for message transmission and reception, allowing the receiving device to determine message validity by comparing the detected interval with the predefined interval, thereby identifying and excluding invalid messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If each ECU can transmit messages to the bus by determination, then message transmission is easy, but invalid ECUs can connect and transmit invalid messages that may be processed as regular messages
Solution Approach 1:
The system performs preliminary actions by having ECUs transmit their identification information to the gateway when the ignition switch is turned off, storing this information in EEPROM as comparison data. When the ignition is turned on, the gateway compares newly transmitted identification information with the stored comparison data before allowing message transmission, thereby preventing invalid messages from being processed.
Solution Approach 2:
The gateway provides feedback by comparing the identification information transmitted by each ECU with the stored comparison data and controlling the transmission of messages based on this comparison result. This feedback mechanism ensures that only valid ECUs can transmit messages on the bus.
2Reliability
If the conventional system uses ignition switch state to detect falsified ECUs, then ECUs can be detected when ignition is off and on, but devices connected via DLC cannot be determined regardless of ignition state
Solution Approach 1:
The system achieves universality by making the gateway perform the same identification information comparison function for all devices connected to the bus, regardless of whether they are ECUs or other devices connected via DLC. The gateway compares identification information from any device with stored comparison data, enabling unified validation across all device types.
3Reliability
If the system stores comparison data in EEPROM, then falsified ECUs can be reliably detected, but the configuration becomes more complex
Solution Approach 1:
The system implements self-service by having the gateway automatically perform the comparison between transmitted identification information and stored comparison data without requiring external intervention. The gateway autonomously determines the validity of each device and controls message transmission based on this automatic comparison.
Data Source
AI summary
To provide a communication system and a communication method that are capable of determining with a simple configuration the validity of a message that is communicated with the communication system, a plurality of ECUs is connected in the communication system to a communication bus, allowing communication of messages. A communication interval, which is defined for each message being communicated, is set for each ECU. The ECU that transmits the message transmits the message on the basis of the defined communication interval. The ECU that receives the transmitted message detects the communication interval of the received message, and determines the validity of the received message on the basis of a comparison between the detected communication interval and the defined communication interval.