io口连续执行测试.asm

单片机开发资料光盘-双龙-686M.zip

;8X51 I/O口实验,连续执行
        ORG     0000H		; 
 L0000:  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)
        ACALL   S00E0		;调用延时子程序
        MOV     P0,#0FFH		;关LED灯,
        MOV     P2,#00H		; P1口开LED灯
        ACALL   S00E0		; 调用延时子程序
        MOV     P2,#0FFH		; 关LED灯
        MOV     P3,#00H
        ACALL   S00E0
        MOV     P3,#0FFH
        MOV     P1,#00H
        ACALL   S00E0
        MOV     P1,#0FFH
	ACALL	S00E0
        SJMP    L0000		;循环
        
        ORG     00E0H	;延时子程序
 S00E0:  MOV     R2,#28H	;延时常数
        ACALL   S00EB
        RET     
        ORG     00EBH	;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