五个按键：关机off键，开机on键，五分钟定时键，十分钟定时键，二十分钟定时键，按相应的按键实现相应的功能，输出4HZ的方波-5 buttons: off off key, turn on key, five minutes from time to time key, 10 minutes from time to time key, 20 minutes from time to time, press the corresponding button to achieve the corresponding functions of the square wave output of 4HZ