單片機實驗之搶答器實驗

電路圖

 

代碼如下

	ORG 0000H
	LJMP MAIN
	ORG 0003H
	LJMP PINT0
	ORG 000BH
	LJMP T0INT
	ORG 0040H
	COUNT EQU 30H
MAIN: MOV SP,#40H
	  SETB EA
	  SETB IT0
AGAIN:MOV P1,#0FFH
	   CLR P3.6
	   CLR F0
	   JB P3.0,$
	   SETB EX0
	   SETB P3.6
	  MOV COUNT,#00H
	  MOV TMOD,#01H
	  MOV TH0,#3CH
	  MOV TL0,#0B0H
	  SETB TR0
	  SETB ET0
WAIT: JB F0,AGAIN
	  MOV A,COUNT
	  CLR C
	  SUBB A,#200
	  JC WAIT
	  CLR TR0
	  SJMP AGAIN
T0INT: MOV TH0,#3CH
	   MOV TL0,#0B0H
	   INC COUNT
	   RETI
PINT0: CLR EX0
	   CLR P3.6
	   SETB F0
	   MOV P1,P2
	   LCALL DELAY
	   RETI;中斷返回，並且清空中斷標誌位
DELAY: MOV R5,#20
D1:MOV R6,#200
D2:MOV R7,#248
   DJNZ R7,$
   DJNZ R6,D2
   DJNZ R5,D1
   RET
   END