文 件 名：test009.c

* 功 能：外部中断1低电平触发实验。

* 硬件条件：1.CPU型号：AT89S52

* 2.晶振：12.000MHz

* 3.用跳线帽短接BEEP_P1.3

* 4.用跳线帽短接KEY3_P3.3

* 5.用跳线帽短接LED11__P1.7-File name: test009.c* Features: low level triggered external interrupt 1 experiment.* Hardware requirements: 1.CPU Model: AT89S52* 2. Crystal: 12.000MHz* 3. Shorted with jumper caps BEEP_P1.3* 4. Shorted with jumper caps KEY3_P3.3* 5. With a short jumper cap Then LED11__P1.7