外部中断和定时器一样，是单片机最基本也是最重要的两个功能.

　　　　　　 我们把它们放在了一起，让大家熟悉单片机的多个内部器件的控制。

　　　　　　 因为P3.2接的J8的1端，所有按键“S19”就是外部中断。

　　　　　　 数码管的最高位一直显示0--9。当“S19”按下后，就会执行一次流水灯的代码。

　　　　　　 因为外部中断0的优先级比定时器0的优先级高。

　　　　　　 在执行流水灯的后，数码上显示的值不会有所变化，让后继续显示。-External interrupts and timers, is the most basic and most important microcontroller two functions we put them together, so that we are familiar with the microcontroller to control multiple internal devices. Because P3.2 connected to J8 of a side, all the buttons " S19"　is an external interrupt. The highest bit digital tube has been show 0- 9. When the " S19"　is pressed, it will perform a light water code. Because the external interrupt 0 priority than the priority of the Timer 0 high. In the implementation of light water, the digital display will not change the value, so that continues to display after.