delay500ms.a51

EasyStudy51-II单片机开发系统的库函数源代码.包含了EasyStudy51-II硬件的全部驱动.

NAME		DELAY500MS
PUBLIC		ES51_DELAY500MS

ES51		segment	code
RSEG		ES51
		
ES51_DELAY500MS:
; 延时500毫秒;[假设时钟为12MHZ];
; 延时间约500ms(500.063ms)
; 1+[(1+1+48*2+2)*250+1+2]*20+2 = 3+(100*250+3)*20 = 500063us = 500.063ms	
	MOV	R0,	#20		; 1us
DELAY500MS_LOOP1:
	MOV	R1,	#250		; 1us
DELAY500MS_LOOP2:
	NOP				; 1
	MOV	R2,	#48		; 1
	DJNZ	R2,	$		; 2*8 
	DJNZ	R1,	DELAY500MS_LOOP2; 2us
	DJNZ	R0,	DELAY500MS_LOOP1; 2us
	RET				; 2us

	END