Adjustable ACK Slot Length for High-Speed CAN Communication
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Solution Overview
Problem
The CAN protocol faces challenges in achieving high-speed communication due to propagation delays, making it difficult to maintain reliable data transfer at speeds above 1 Mbps, especially in motor vehicle networks with increased information volume and complex unit connections.
Innovation Solution
The solution involves an ECU with a semiconductor integrated circuit device that allows arbitrary adjustment of the ACK slot length, enabling increased communication speed without being limited by harness length or processing delays, by changing the ACK slot length to accommodate different communication frequencies and speeds among ECUs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If communication speed is increased to 1 Mbps or higher, then data transfer speed is improved, but propagation delay causes ACK bit reception failure
Solution Approach 1:
The patent applies dynamics by making the ACK slot length adjustable rather than fixed. The ECU can dynamically change the ACK slot length based on communication speed requirements, allowing the system to adapt to different operating conditions. This resolves the contradiction by enabling high-speed communication when needed while maintaining protocol compatibility through flexible configuration.
Solution Approach 2:
The patent changes the parameter of ACK slot length from a fixed value to a variable parameter that can be adjusted according to communication speed. By modifying this critical parameter, the system can achieve higher data transfer speeds while ensuring reliable ACK bit reception, thereby resolving the contradiction between speed and reliability.
2Adaptability or versatility
If ACK slot length is fixed at 1 bit, then protocol compatibility is maintained, but communication speed is limited by propagation delay
Solution Approach 1:
The patent makes the ACK slot length dynamic and adjustable, allowing the system to maintain protocol compatibility at standard speeds while achieving higher communication speeds when needed. This flexibility resolves the contradiction between adaptability and speed by enabling the system to adapt to different requirements.
Solution Approach 2:
The patent changes the ACK slot length parameter from fixed to variable, allowing the system to optimize communication speed without sacrificing protocol compatibility. This parameter change enables the system to achieve high-speed communication while maintaining compatibility with existing CAN protocol standards.
3Productivity
If communication speed is increased, then information processing capability is improved, but harness length and processing delay become limiting factors
Solution Approach 1:
The patent changes the ACK slot length parameter to optimize the balance between communication speed and system complexity. By adjusting this parameter, the system can achieve higher information processing capability while managing the complexity introduced by longer transmission times and potential race conditions.
Data Source
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AI summary
In the upgrading of the ECU, an ECU 1 to be a master notifies other ECUs 1a and 1b of change of an ACK slot length. The ECUs 1a and 1b change the ACK slot length into an ACK slot length received from the ECU 1. At this time, the changed ACK slot length is stored in each register 5a provided in the ECUs 1a and 1b. Subsequently, the master ECU 1 transmits an upgrade data to each of the ECUs 1a and 1b at a communication speed corresponding to the changed ACK slot length. After completion of the upgrade, the ECU 1 notifies of change of the ACK slot length into the original ACK slot length. After receiving this, the ECUs 1a and 1b reset the ACK slot length to the notified original ACK slot length.