1）设置3个变量，假如A，B，C，其中A在主程序里循环计数，计数间隔为1秒左右（不需要很精确），从0-9循环计数；B在外部中断0程序中计数，计数间隔为1秒左右（不需要很精确），从0计数到9，中断退出；C在外部中断2程序中计数，计数间隔为1秒左右（不需要很精确），从0计数到9，中断退出；外部中断0，1采用下降沿触发，通过按键触发。为了便于观察，P1连接到数码管，P2.0-P2.2对应A，B，C计数选通，每计数一次，将变量输出到数码管上，即在主程序里显示数码管4，在中断0里显示数码管5，在中断1里显示数码管6。设置外部中断0为高级中断，外部中断1为低级中断。改变按键顺序观察LED显示。-1) Set three variables, if A, B, C, where A in the main program loop count, the count interval of 1 second or so (need not be very precise), cycle count from 0-9　B program in the external interrupt 0 counting, counting interval is 1 second or so (need not be very precise), counts from 0 to 9, interrupt exit　C program in the external interrupt 2 count, the count interval is 1 second or so (need not be very precise), counts from 0 to 9, interrupt exit　0,1 using falling edge triggered external interrupt, triggered by the button. In order to facilitate the observation, P1 is connected to the digital control, P2.0-P2.2 corresponds to A, B, C count strobe, each counted once, the variable output to digital, is displayed in the main program of digital tube 4, Interrupt 0 5 in the digital display, digital display interrupt an inside tube 6. Set External Interrupt 0 is a senior interrupt, external interrupt 1 is lower interrupt. LED display keys change the order observed.