The electric circuit's diagram includes the switch K1,the first electric resistance R1,the second electric resistance R2,the third electric resistance R3,the electric capacity C1,the LED( the Light Emitting Diode,give out light the diode) L1,the first needle feet P1,the second needle feet P2 and provide the power supply V1 of the 3.3 V electric voltage.Among them,say the first needle feet P1,the first electric resistance R1,the switch K1,the third electric resistance R3,the LED L1,the second needle feet P2 carries on establish one by one in order,say the second electric resistance R2 and the electric capacity C1 say merges the conjunction,shoulding merge the conjunction on carrying to link say the first needle feet P1 passes one an on-line of the electric resistance R1,another on carrying to connect the ground.The power supply V1 say connect the switch K1 with the on-line between the third electric resistance R3.The cathode of the LED L1 say link the third electric resistance R3,the anode link the second needle feet P2.The electric capacity C1 cathode say link say the first needle feet P1 passes one an on-line of the electric resistance R1,the anode connects the ground.The switch K1 say return with the input device say 2 medium an importation key conjunction,be press that input device 2 the importation key that should correspond mediumly,the switch K1 close,the first needle feet P1 carry electricity even and high,thus produce the hardware interruption.When the system sends out the high electricity even give the second needle feet P2,because of the LED L1 another on carrying to have the power supply V1 through the electric resistance R3 conjunction,the LED's L1 connects the electric circuit of the place,the LED's L1 has the electric current to pass,for this reason hour the LED's L1 is bright;When the system sends out the low electricity even give the second needle feet P2,in the LED's L1 there is no electric current pass,the LED's L1 of for this reason hour put out;When the system send out high and low interrupted the electricity even give the second needle feet P2,in the LED's L1 interrupteding the electric current to pass,for this reason hour the LED's L1 flicker.