实验采用七段码LED设计（数码管），显示直观；采用定时器中断，计时更准确；功能齐全，可随时启动、停止、清零，后者智能化程度更高。-Seven-Segment LED code using the experimental design (digital control), visual display using timer interrupt, a more accurate time functions, may at any time to start, stop, cleared,