$MOD51
RESET		EQU	0000H
STACK		EQU	50H
COUNT_PLUSE	EQU	200D	;設定送出200個pluse後結束
COUNT		EQU	25D	;存放count_pluse
SEL		EQU	P2.7	;encoder判斷讀取高btye或低btye
OE		EQU	P2.6	;encdoer讀取接腳
OLD		EQU	26D	;encoder舊值暫存器
		
		ORG	RESET
		MOV	P0,#00H
		CLR	OLD
		MOV	SP,#STACK
		SETB	SEL
		SETB	OE
LOOP1:
		MOV	OLD,DPL
		CLR	SEL	;讀取高btye
		CLR	OE	;開始讀取
		MOV	DPH,P0	;高btye放入dph
		SETB	SEL	;讀取低btye
		MOV	DPL,P0	;低btye放入dpl
		SETB	OE	;停止讀取
		MOV	A,DPL		;[[
		SUBB	A,OLD		;  與舊值相減判斷是否有讀取新值
		CJNE	A,#00H,START	;]]
		JMP	LOOP1
START:		
		MOV	R3,#200D	;設定馬達輸出pulse
		MOV	A,#01110111B
LOOP:		RL	A		;不斷移動位元
		MOV	P1,A		;信號由p1輸出
		CALL	DELAY	
		DJNZ	R3,LOOP		;將200個pluse減到0
		jmp	LOOP1
DELAY:		
		MOV	R0,#10D
DEL:		MOV	R1,#2D
DE:		MOV	R2,#112D
		DJNZ	R2,$
		DJNZ	R1,DE
		DJNZ	R0,DEL
		RET
		END