# Design of Time-Synchronized Switch Based on Zynq
## 1 Introduction  
Time synchronization technology plays a crucial role in multiple key areas, particularly in China's spallation neutron source, where neutron spectrometer experiments generate neutrons by bombarding a target material with proton beams and collecting information on each neutron pulse corresponding to the proton pulse. In this process, the beam monitoring nodes need to maintain absolute clock synchronization to ensure the accuracy of the data and the reliability of the experimental results. The demand for high-precision clock synchronization is not only applicable to neutron spectrometer experiments but also plays an important role in various critical fields such as radar, radio frequency systems [1], synchrotron accelerators, and smart grids [2]. Therefore, in-depth research and optimization of clock synchronization technology have broad application prospects. As the demand for time precision in these fields continues to increase, the need for switching devices capable of supporting high-precision time synchronization has also surged. Switches, as core devices for data transmission and synchronization signal distribution, play a vital role in building reliable low-latency network architectures. Consequently, switches equipped with advanced time synchronization technology have become essential infrastructure to meet the demands of modern applications. Network time synchronization technologies such as NTP [3; 4; 5], PTP [6; 7], and dedicated fiber optic time synchronization have been widely used in various scenarios. However, each of these technologies has certain limitations and cannot meet the stringent accuracy requirements for time synchronization in demanding fields. Especially in time-sensitive fields that require ultra-high timing and synchronization performance, such as national time and frequency laboratories and particle accelerators, these traditional technologies often fall short. In order to overcome these challenges, White Rabbit (WR) technology [8] has emerged. WR technology is a sub-nanosecond clock synchronization technology based on standard Ethernet [9], jointly proposed by the European Organization for Nuclear Research (CERN) and the GSI Helmholtz Centre for Heavy Ion Research in 2008. With its outstanding performance, it not only overcomes the limitations of traditional time synchronization technologies but also offers numerous significant advantages. WR technology supports frequency distribution and time synchronization over multiple nodes and long distances [10; 11]. It is fully compatible with standard gigabit Ethernet protocols and features low cost, high bandwidth, high reliability, and flexible topology, among other characteristics. This gives WR technology tremendous application potential in time-sensitive fields, as it not only meets the stringent requirements for time synchronization accuracy but also promotes the further development of time synchronization technologies. It opens up new possibilities for the diversification of future time synchronization applications. As an innovative technology in the field of time synchronization, WR technology is leading the way toward a new era of greater precision, efficiency, and reliability in this domain. WR switches (WRS) are the core components of WR networks. They are built upon standard switches with added WR functionality and provide features such as QoS support, link redundancy, and fast switching to meet the high real-time requirements of clock and control systems. Additionally, they can distribute time-frequency signals to multiple connected WR devices, enabling the construction of time synchronization networks with nearly ten thousand nodes.