数字钟电路系统由主体电路和扩展电路两大部分组成。其中，主体电路完成数字钟的基本功能，扩展电路完成数字钟的扩展功能。用MAXPLUSⅡ进行电路设计与仿真.-digital clock circuit system from the main circuit and the circuit extended two major components. Among them, the main circuit digital clock to complete the basic functions, expanding digital clock circuit to complete the expansion function. II FPGA used for circuit design and simulation.