在工业控制领域中，我们需要比较精确的定时信号。比如在现代大型加速器中，触发信号，是由中央控制室的一个500MHz的时钟源，经过不同的分频和延时处理后，提供给其他器件作为触发源使用。采用这样的方式，可以做到统一管理触发，并且各个延时触发信号之间具有相关性，彼此间的晃动比较小。本次设计计划实现一个扇出比是4的小型触发延时系统，主要包括两部分功能：一是对于已知的系统外部信号进行延时；二是系统根据要求产生一些触发信号，并根据要求进行延时。系统的延时时间，触发信号的频率和脉冲宽度能够根据实际需要通过远端的PC进行实时调整。

In the industry control domain, we need an accurate source of particular signals. Such as the touch off signal in a modern accelerator which is larger and larger. This signal is created by a 500MHz clock provided by the control center, through different counter, delay and other operations, then touch off other constitutions of the accelerator. Using this signal, we can unify the work time of all the instruments of the accelerator, and the touch off signals are related from each other, the twitter among the signals is small. In addition, the signals need more accurate than other sources. We plan to design a delay-system including 4 fans. The function of the system is to generate signal and control the signals by itself and delay the signals input from other system. Moreover, the system will fulfill the requirement that we can use a PC to control the PRF and the wideness of the pulse anytime.

系统原理是通过串口，PC和FPGA通信传递延时参数，同时FPGA和I2C连接，用于存储延时参数。由于整个系统用到的时钟较多，所以调用DCM模块进行时钟管理，同时通过DCM的倍频功能提高系统精度。在串口通信中，通过FCS校验保证数据的准确性。