Distributed Synchronization Time System on EAST Tokamak

A key item for the EAST distributing control system (EASTDCS) was the synchronization, the EASTDCS required the synchronized with an accuracy of < 1 mus. A distributed synchronization time system (DSTS) was setup, which was based on the AVR microcontroller ATmegal28 and the embedded RTOS Nut/OS, in 2006. The synchronization chassis contained a main unit and many local units. The DSTS provided analog outputs to separate the control systems and the data acquisition systems with unification clocks (0.01Hz~10MHz) and different delay trigger times (1 mus ~4294 s). The optical fiber (same length) net was used to connect with main unit and the local units, in order to eliminate the pick up of the ground noise and to keep the synchronized clock and the accuracy delay time for each system. This paper described the architecture of the DSTS on EAST tokamak and an overview of the characteristics of the main and local unit.