GPS-PPS Time Synchronization for Low-CPU Intelligent Driving
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Solution Overview
Problem
Existing time synchronization methods for intelligent driving systems, such as Precision Time Protocol (PTP) and generalized Precision Time Protocol (gPTP), require Ethernet communication and high CPU usage, making them costly and unsuitable for low-end CPUs, and they do not provide accurate time synchronization without increasing hardware costs.
Innovation Solution
A time synchronization method using a GPS module to provide second-level universal time and a Pulse Per Second signal, combined with hardware timestamp capture and software delay compensation, to achieve high-precision time synchronization across multiple processing units in an intelligent driving system without additional hardware costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PTP or gPTP protocols are used for time synchronization, then time synchronization accuracy can be achieved, but hardware costs increase due to Ethernet dependency and additional hardware requirements
Solution Approach 1:
The patent extracts the essential time synchronization function from complex Ethernet-based protocols (PTP/gPTP) and implements it using a simplified GPS module combined with hardware timestamp capture and software delay compensation. This removes the dependency on expensive Ethernet infrastructure while retaining the core time synchronization capability, directly resolving the contradiction between accuracy and hardware cost.
Solution Approach 2:
The patent replaces expensive, complex Ethernet-based time synchronization hardware with a more economical GPS module solution. The GPS module provides adequate time synchronization accuracy for intelligent driving systems at a lower hardware cost, effectively substituting expensive infrastructure with a more affordable alternative that meets the system's needs.
2Measurement precision
If PTP or gPTP protocols are used for time synchronization, then time synchronization can be achieved, but CPU usage increases significantly
Solution Approach 1:
The patent performs time synchronization in advance using GPS time stamps and hardware timestamp capture, storing the synchronized time information for later use. This preliminary action eliminates the need for continuous CPU-intensive protocol processing during normal operation, significantly reducing CPU usage while maintaining synchronization accuracy.
Solution Approach 2:
The patent replaces the software-based PTP/gPTP protocol processing (which requires significant CPU resources) with a hardware-based timestamp capture mechanism. The hardware automatically captures time stamps at predetermined edges of the PPS signal, transferring the synchronization workload from the CPU to dedicated hardware circuits, thereby reducing energy consumption and CPU usage.
3Measurement precision
If hardware timestamp capture is used to achieve high-precision time synchronization, then time accuracy improves to nanosecond level, but system complexity increases
Solution Approach 1:
The patent uses a GPS module that serves multiple functions: providing both the PPS signal for hardware timestamp capture and the second-level universal time for software delay compensation. This multi-functionality reduces the need for separate components, achieving nanosecond-level accuracy without proportionally increasing system complexity.
Solution Approach 2:
The patent introduces a GPS module as an intermediary that provides a standardized PPS signal and time information, bridging the external time source and the internal hardware timestamp capture mechanism. This intermediary simplifies the interface between different subsystems, making the overall system more manageable despite the increased precision requirements.
Data Source
AI summary
Provided are a time synchronization method, a time synchronization system of an intelligent driving system, an electronic device and a storage medium, relating to the technical fields of autonomous driving, electronic technology, and time synchronization. The method includes: obtaining a second-level universal time and a corresponding Pulse Per Second signal; based on a first local timestamp of a captured Pulse Per Second signal, a second local timestamp of an execution time instant of an interrupt service routine, and a first global timestamp, determining a second global timestamp corresponding to a predetermined edge of the Pulse Per Second signal; based on a global timestamp of a current time instant and the second global timestamp, obtaining a sub-second time of the current time instant; based on the second-level universal time and the sub-second time, obtaining an accurate time of the current time instant.