AT89S51单片机的P1.0－P1.3接四个发光二极管L1－L4，P1.4－P1.7接了四个开关K1－K4，编程将开关的状态反映到发光二极管上。（开关闭合，对应的灯亮，开关断开，对应的灯灭）-AT89S51 MCU P1.0-P1.3 next four light-emitting diodes L1-L4, P1.4-P1.7 next four switches K1-K4, programming will reflect the status of switches on the light-emitting diodes. (Switch closed, the corresponding lights, switch off, the corresponding lights out)