P1口做输出口，接八只发光二极管，绘制仿真电路图，硬件连接表见3-1。

①编写C51程序，采用软件延时的方式实现发光二极管的每秒闪烁。

②编写C51程序，使8个发光二极管从右到左（上到下）逐一点亮。

③编写C51程序，使8个发光二极管从两边到中间顺序点亮，直至全部点亮，然后从中间到两边顺序熄灭，直至全部熄灭，如此循环下去。

-P1 port as the output port, then eight light-emitting diodes, circuit simulation rendering, hardware connections see table 3-1.

① write C51 procedures, software delay means to achieve light emitting diode flashes per second.

② write C51 program that allows eight LEDs　right to left (top to bottom) lit one by one.

③ write C51 program that enables 8 LEDs lit　both sides to the middle of the order, until all the lights, then goes out to both sides　the middle order, until all off, so the cycle continues.