正常情况下，p1口所接的发光管依次循环点亮。当s1按下时，产生int0中断，此时8只发光管全亮全暗交替八次。然后回复正常-Under normal circumstances, p1 port of LED then turn the light cycle. When s1 is pressed, the resulting int0 interrupt, then 8 LED light all dark turn all eight. Then back to normal