Long Time And High Precision Design Of The Timer Based On ARM

Along with the development of magnetic confinement fusion research and engineering technology, the EAST Tokamak has achieved a stable operation for hundreds of seconds. Integrator equipment as a front end to the various kinds of magnetic field signal processing link, whether it can realize long time low drift of integral function, the signal subsequent proper treatment is essential. The integrator function, accurate time signal, is the premise and foundation of the primary.In this paper, the central timing system of the EAST Tokamak time parameters,in the analysis of the integrator equipment required to function on the basis to determine the timer system architecture design, and accordingly the components selection, builds a hardware platform based on ARM processor. System software part,on the basis of the current research of the embedded system, comprehensive consideration of communication and information security and other factors, determine the Linux system as a software program, and completed the Linux kernel cutting and transplantation. According to the requirement of timing task in real time, analyzing the processor interrupt the process, combined with the Linux scheduling mechanism,put forward the concept of real-time task to design a in the soft real-time system platform, strong real-time task processing realization mechanism, to compensate for a Linux system weak real-time aspects of effective research. In order to realize the precise timing function, this paper analyzes and studies the two ways of the internal timer and external counter. Through theoretical analysis and experimental analysis,the realization method of timing accuracy and length expansion is determined.Through MFC programming, this system is designed by the computer interface of thehost computer, and the operation of the timer system is realized by serial communication. In the test section, the time difference between three channels is measured by using high performance time interval measuring equipment SR620, and the accuracy and time length parameters of the system are determined.The test results show that the embedded high precision timer is designed in this paper, and the timing accuracy is 40 ns, the maximum is 20990 s. The design scheme is easy to extend, and it can effectively solve the problem of the timer’s accuracy and time. It has a significant effect on the EAST Tokamak front-end signal processing equipment, improve the performance of the integrator.