基于CPLD的棋类比赛计时时钟,第一个CNT60实现秒钟计时功能，第二个CNT60实现分钟的计时功能，CTT3完成两小时的计时功能。秒钟计时模块的进位端和开关K1相与提供分钟的计时模块使能，当秒种计时模块计时到59时向分种计时模块进位，同时自己清零。同理分种计时模块到59时向CTT3小时计时模块进位，到1小时59分59秒时，全部清零。同时，开关K1可以在两小时内暂停秒钟计时模块，分钟计时模块和小时计时模块。各模块的VHDL语言描述如下：-CPLD-based time clock chess competitions, a CNT60 achieve seconds timing, CNT60 second minute of time to achieve functional, CTT3 completion of the two-hour time function. Module seconds into time - and-switch K1 phase minutes for a time module can be enabled When seconds time to time module to the 59 minute time rounding module, reset themselves. Similarly minute time module to the 59-hour time CTT3 module rounding to 1 hour 59 minutes 59 seconds, reset all. Meanwhile, switches K1 can be suspended within two hours time module seconds, minutes and hours of time metering module module. The module VHDL is described as follows :