4x4 keyboard (2).asm

keil c51 4×4键盘

LINE	EQU		30H
ROW		EQU		31H
VAL		EQU		32H
		ORG		00H
START:	MOV		DPTR,#TABLE	;段码表首地址
		MOV		P2,#00H		;数码管显示初始化

LSCAN:	MOV		P3,#0F0H	;列线置高电平,行线置高电平
L1:		JNB		P3.0,L2		;逐行扫描
		LCALL	DELAY
		JNB		P3.0,L2
		MOV		LINE,#00H	;存行号
		LJMP	RSCAN
L2:		JNB		P3.1,L3
		LCALL	DELAY
		JNB		P3.1,L3
		MOV		LINE,#01H	;存行号
		LJMP	RSCAN
L3:		JNB		P3.2,L4
		LCALL	DELAY
		JNB		P3.2,L4
		MOV		LINE,#02H	;存行号
		LJMP	RSCAN
L4:		JNB		P3.3,L1
		LCALL	DELAY
		JNB		P3.3,L1
		MOV		LINE,#03H	;存行号

RSCAN:	MOV		P3,#0FH		;行线列线电平互换
C1:		JNB		P3.4,C2		;逐列扫描
		MOV		ROW,#00H	;存列号
		LJMP	CALCU
C2:		JNB		P3.5,C3
		MOV		ROW,#01H	;存列号
		LJMP	CALCU
C3:		JNB		P3.6,C4
		MOV		ROW,#02H	;存列号
		LJMP	CALCU
C4:		JNB		P3.7,C1
		MOV		ROW,#03H	;存列号	

CALCU:	MOV		A,LINE		;根据行号和列号计算键值
		MOV		B,#04H
		MUL		AB
		ADD		A,ROW
		MOV		VAL,A		;存键值

		MOVC	A,@A+DPTR	;要据键值查段码
		MOV		P2,A		;输出段码显示

		LJMP	LSCAN

DELAY:	MOV		R6,#20
D1:		MOV		R7,#250
		DJNZ	R7,$
		DJNZ	R6,D1
		RET

TABLE: 	DB 		3FH,06H,5BH,4FH,66H,6DH,7DH,07H
		DB 		7FH,6FH,77H,7CH,39H,5EH,79H,71H

END