基于VxWorks和FPGA的授时系统设计与实现

Design and implementation of timing system based on VxWorks and FPGA

摘要:

时间同步是海洋石油地震勘探中各系统协同工作的前提，同步精度直接影响着地震数据的精度。设计了一套基于嵌入式实时操作系统VxWorks和FPGA的授时系统，精度优于50us。该系统采用工控VME机箱作为各模块载体，基于GPS时间源和FPGA三级计时器进行精准时钟守护；软件基于VxWorks设计，详细介绍了基于SNTP协议的网络时间服务编程方法；同时基于GPIO设计了一套通讯协议实现软件模块和FPGA模块的通讯。该系统在中国海洋石油物探船上实际应用结果表明：授时精度满足海洋石油勘探的时间同步精度要求，长时间且稳定的提供时间服务满足可靠性要求。在不失实时性和精度的前提下，该系统采用了模块块化设计，良好的扩展能力，使之易于扩展出具有时间标定或时间服务的应用系统。

Abstract:

Time synchronization is the prerequisite for all systems to work together in offshore oil seismic exploration, while the synchronization accuracy directly affects the accuracy of seismic data. A timing system based on embedded real-time operating system VxWorks and FPGA (field programmable gate array) is designed, and the timing accuracy is better than 50us. It uses the industrial control VME chassis as the carrier of each module, and uses the time source of GPS and three-level timer of FPGA to guard clock precisely . Based on VxWorks, the software’s programming method of network time service based on SNTP protocol is introduced in detail. Meanwhile, a set of communication protocol based on GPIO is designed to realize the communication between software module and FPGA module. The timing system’s practical application results on the China Offshore Petroleum Geophysical Survey ship show that the timing accuracy can meet the requirements of time synchronization accuracy for offshore oil exploration, and the long and stable time service can meet the requirements of reliability. On the premise of losing real-time and accuracy, the system adopts modular design and good expansion ability, which makes it easy to expand the application system with time calibration or time service.