8-10-2.asm

书籍8051入门篇

;8-10-2.ASM
BUFFER		DATA	20H
TEST_BIT	BIT	20H.4
$MOD51
		ORG	0000H		
		MOV	BUFFER,#00H
		MOV	P1,#0FFH		;LED全部OFF
CHECK:	INC		BUFFER
		JB	TEST_BIT,ALL_ON		;TEST_BIT?
;
;TEST_BIT=0
ONLY_ONE:					;TEST_BIT=0
		CLR	P1.0			;1 LED ON
		ACALL	DELAY			;延迟
		SETB	P1.0			;1 LED OFF
		ACALL	DELAY
		SJMP	CHECK			;重新检查
;
;TEST_BIT=1
ALL_ON:		MOV	P1,#00H			;ALL LEDS TURN ON
		ACALL	DELAY	
		MOV	P1,#0FFH		;ALL LEDS TURN OFF
		ACALL	DELAY
		SJMP	CHECK			;重新检查
	
DELAY:		MOV	R0,#00H
DLY1:		MOV	R1,#00H
		DJNZ	R1,$
		DJNZ	R0,DLY1
		RET
		END