key扫描 线反转法.asm

矩阵键盘扫描扫描之线反转法.asm把扫描到的键值

      ORG  0000H
;******P1.7~P1.4为列线的4~1
;******P1.3~P1.0为行线的4~1
      MOV   SCON,#50H;串口工作在1方式可以接收
      MOV   PCON,#00H
      MOV   TMOD,#20H;波特率发生器T1工作在模式2上
      MOV   TL1,#0F3H;预置初值(按照波特率2400BPS预置初值)
      MOV   TH1,#0F3H;预置初值(按照波特率2400BPS预置初值)
      SETB  TR1;启动定时器T1

S:    ACALL KEYSCAN
      MOV   SBUF,R3
      JBC   TI,$
      SJMP  S


	KEY  EQU  50H
KEYSCAN:MOV  P1,#0FH
	MOV  A,P1
	ANL  A,#0FH
	MOV  B,A
	MOV  P1,#0F0H
	MOV  A,P1
	ANL  A,#0F0H
	ORL  A,B
	CJNE A,#0FFH,KEYREAD
	AJMP KEYSCAN
;-------键盘数据读取---
KEYREAD:MOV   KEY,A
	MOV   DPTR,#KEYDB
	MOV   R3,#0FFH
REW:    INC   R3
	MOV   A,R3
	MOVC  A,@A+DPTR
	CJNE  A,KEY,REW
	MOV   30H,R3
	RET
KEYDB:
DB 0E7H,0D7H,0B7H,77H,0EBH,0DBH,0BBH,7BH,0EDH,0DDH,0BDH,7DH,0EEH,0DEH,0BEH,7EH,0FFH	
;**********************10MS      
DEL10MS:MOV   R7,#50
DEL11:  MOV   R6,#100
DEL10:  DJNZ  R6,DEL10
        DJNZ  R7,DEL11
        RET        
        END