Identification of a key multi-function button schematics

The switch SP1 connected to the P3.7 / RD pin as shown in the AT89S51 microcontroller P1 port is connected with four light-emitting diodes, power, when, L1 connected to the P1.0 pin at the blinking light-emitting diodes When the switch is pressed SP1 every time, L2 connected to the P1.1 pin LED is flashing, then press the switch when SP1, L3 connected to the P1.2 pin LED blinking, and then Press the switch when SP1, L4 connected to the P1.3 pin LED blinking, and then press the switch SP1, when they turn in the blink of L1, so turn down.

　　(1 of the "SCM system" area of ​​P3.7 / RD port is connected to the "stand-alone keyboard" area of ​​SP1 port;

　　(2 of the "SCM system" area of ​​P1.0 - P1.4 port with 8-core cable connected to the "Eight LEDs indicate module" area - the "L1 L8" port; requirements, P1 .0 connection to L1, P1.1 connected to L2, P1.2 connected to L3, P1.3 connected to L4.