low.asm

6502的汇编代码

DSD        BIT     P1.2    ;数据线
CSD        BIT     P1.3    ;片选线
KSD        BIT     P3.2    ;键控线
KEYNUM     EQU     20H     ;按键次数
STATUS     EQU     21H     ;STATUS.0   发声请求 1 有效
;--------------------------------------------------------
           ORG     0000H
           SJMP    REST
REST:      MOV     SP,#60H   ;初始化控制信号
           CLR     EA
;--------------------------------------------------------
DATA1:     CLR     DSD
           ACALL   DLAY_320US
           SETB    DSD
           ACALL   DLAY_640US
           SJMP    DATA1

;------------------------------------------------------------
DLAY_320US:MOV     R7,#158D
DS1:       DJNZ    R7,DS1
           NOP
           RET
DLAY_640US:MOV     R7,#91D
DS2:       MOV     R6,#02H
DS3:       DJNZ    R6,DS3
           DJNZ    R7,DS2
           RET
DLAY_720US:MOV     R7,#03H
DS4:       MOV     R6,#118D
DS5:       DJNZ    R6,DS5
           DJNZ    R7,DS4
           RET
DLAY_20MS: MOV     R7,#0FFH
DS6:       MOV     R6,#0FFH
           NOP
           NOP
           NOP
           NOP
DS7:       DJNZ    R6,DS7
           NOP
           NOP
           NOP
           NOP
           NOP
           DJNZ    R7,DS6
           RET
;-------------------------------------------------------------
END