4口亮灭.asm

单片机开发资料光盘-双龙-686M.zip

       ORG     0000H
        LJMP    L0300
        ORG     0300H
L0300:  LJMP    LP03
        ORG     0350H           ;NICE-8751 I/O口实验,连续执行,
LP03:  MOV      P0,#00H        ;P0口开LED灯(设低电平LED灯亮,I/O用灌电流,减轻CPU功耗)
	MOV     P1,#00H
	MOV     P2,#00H
	MOV     P3,#00H
        ACALL   S00E0		;调用延时子程序
        MOV     P0,#0FFH	;关LED灯,
        MOV     P1,#0FFH
        MOV     P2,#0FFH
        MOV     P3,#0FFH
        ACALL   S00E0		; 调用延时子程序
        SJMP    L0300           ;循环
        ORG     0380H           ;延时子程序
 S00E0:  MOV     R2,#20H	;延时常数
        ACALL   S00EB
        RET     
        ORG     00385H        ;通用延时子程序
 S00EB:  PUSH    02H
 L00ED:  PUSH    02H
 L00EF:  PUSH    02H
 L00F1:  DJNZ    R2,$
        POP     02H
        DJNZ    R2,L00EF
        POP     02H
        DJNZ    R2,L00ED
        POP     02H
        DJNZ    R2,S00EB
        RET
        END