key.asm

通信基带信号发生器的设计

  ;-----------键盘扫描相关-----------
        KEYH  EQU 30H          ;待扫描行线
        KEYL  EQU 31H          ;待扫描列线
        KEYZ  EQU 32H          ;按键值
        KEYN  EQU 33H          ;指示待扫描行

        ORG 0000H
        SJMP START
        ORG 0040H
START:  MOV SP,#68H           ;主程序入口
KEY1: MOV P1,#0F0H          ;行线为P0-P3,列线为P4-P7
      MOV A,P1
      ORL A,#0FH
      CPL A
      JNZ IN
      SJMP KEY1

IN:   ACALL DELAY
      MOV KEYH,#04H
      MOV KEYN,#07FH    ;做指针,指示待扫描行
      MOV KEYZ,#0
SCAN: MOV A,KEYN
      RL A
      MOV KEYN,A
      MOV P1,A          ;逐行扫描,被扫描行送低
      MOV A,P1          ;读列线电平值
      SWAP A
      MOV KEYL,#04H
KEY2: RRC  A
      JNC FIND          ;C位不为1转
      INC KEYZ
      DJNZ KEYL,KEY2
      DJNZ KEYH,SCAN
      SJMP KEY3

FIND:  MOV P1,#0F0H
LOOSEN:MOV A,P1
       ORL A,#0FH
       CPL A
       JNZ LOOSEN

KEY3:  SJMP START
       
;**************************键盘20MS延时**************************************
DELAY:MOV R6,#15H
DL2:  MOV R7,#18H
DL1:  NOP
      NOP
      DJNZ R7,DL1
      DJNZ R6,DL2
      RET       

       END