TTCAN Controller Global Time Sync via Event-Controlled CAN
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Solution Overview
Problem
Existing CAN bus systems face challenges in providing global time information without the need for time control and the complex setup of a complete system matrix, especially in applications where time control is not feasible or practical.
Innovation Solution
A modified TTCAN controller that operates in a special mode allowing event-controlled CAN communication while utilizing hardware for global time synchronization, eliminating the requirement for time-controlled communication and system matrix setup, and allowing configuration between TTCAN and event-controlled modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If TTCAN Level 2 protocol is used to provide global time information, then all subscriber stations can be synchronized with uniform global time information, but the system requires complex time control and complete system matrix setup
Solution Approach 1:
The patent extracts only the essential time synchronization functionality from the complete TTCAN Level 2 protocol. Instead of implementing the full time-triggered communication system with system matrix, the invention uses a simplified approach where a single node transmits time information in CAN messages without requiring the complex coordinated time window structure of TTCAN. This extracts the beneficial time synchronization capability while eliminating the unnecessary complexity of the complete TTCAN framework.
Solution Approach 2:
The patent segments the time synchronization function from the overall communication protocol. Rather than requiring the entire TTCAN Level 2 protocol stack including system matrix configuration, time window allocation, and coordinated arbitration, the invention isolates and implements only the time stamp transmission and reception mechanism. This segmentation allows global time information to be provided independently of the complex time-controlled communication infrastructure.
2Measurement precision
If time-controlled communication is implemented according to TTCAN, then global time information is provided, but the effort and resources required for creating and maintaining the system matrix are unjustifiably high
Solution Approach 1:
The patent implements a self-service approach where nodes autonomously extract and process time information from received CAN messages without requiring centralized coordination or system matrix management. Each node independently parses time stamps from messages, calculates time differences, and adjusts its local clock accordingly. This eliminates the need for complex system matrix creation and maintenance while still achieving accurate global time synchronization across all nodes.
Solution Approach 2:
The patent applies partial action by implementing only the necessary portion of time synchronization functionality required for the application. Instead of fully implementing time-controlled communication with all its overhead, the invention uses standard event-driven CAN communication with added time stamp fields. This partial implementation provides sufficient global time information for most applications without the excessive resources required for complete TTCAN compliance.
3Adaptability or versatility
If standard event-controlled CAN communication is used, then communication flexibility is maintained, but global time information cannot be provided
Solution Approach 1:
The patent merges event-driven communication flexibility with time synchronization capabilities by adding time information fields to standard CAN messages. The system maintains the natural event-triggered communication paradigm where nodes transmit data when events occur, but simultaneously includes time stamps in these messages. This combination allows the system to benefit from both event-driven flexibility and the ability to provide global time information without requiring separate time-controlled communication channels.
Solution Approach 2:
The patent makes the CAN communication system multi-functional by enabling it to serve both event-driven data exchange and time synchronization purposes simultaneously. The same communication infrastructure used for regular data transmission is also used to convey time information through included time stamp fields. This universality eliminates the need for separate dedicated time synchronization protocols while maintaining communication flexibility and providing global time information.
Data Source
Figure 1
Figure 2~3
AI summary
An apparatus and a method are proposed for interchanging data in messages between subscribers (101-105) in a CAN bus system (100), wherein the subscribers (101-105) have their own time bases (106-110), wherein a first subscriber (101) transmits a reference message (RN) with a predeterminable tag via the bus (100) in a function as a timer, which reference message (RN) contains first time information relating to the time base (106) of the first subscriber, wherein the at least second subscriber (102-105) forms its own second time information (IZ1- IZ4) by means of its time base (107-110), depending on the first time information of the first subscriber, such that a correction value is determined from the discrepancy (OS1- OS4) between the first and the second time information items, such that the global time (gZ) for the bus system is obtained from the first time information of the first subscriber as a timer, and wherein configuration means are provided, which make it possible to interchange the messages between the subscribers in the CAN bus system on an event-controlled basis, in accordance with the arbitration method known from the CAN Standard.