开关SP1接在P3.7/RD管脚上，在AT89S51单片机的P1端口接有四个发光二极管，上电的时候，L1接在P1.0管脚上的发光二极管在闪烁，当每一次按下开关SP1的时候，L2接在P1.1管脚上的发光二极管在闪烁，再按下开关SP1的时候，L3接在P1.2管脚上的发光二极管在闪烁，再按下开关SP1的时候，L4接在P1.3管脚上的发光二极管在闪烁，再按下开关SP1的时候，又轮到L1在闪烁了，如此轮流下去。-Switch connected to the P3.7/RD pin SP1, P1 in the AT89S51 microcontroller port has four LEDs connected, when power, L1 connected to the P1.0 pin at the flashing LED on, when every time you press When the switch SP1, L2 connected to the P1.1 pin on the LED is flashing, then press the time switch SP1, L3 connected to the P1.2 pin on the LED is flashing, then press the switch to SP1, time, L4 connected to the P1.3 pin on the LED is flashing, then press the switch to SP1, when they turn in the blink of L1, so turn down.