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<第3題>

;OFF (P0.3)優先

;ON (P0.2)

;第一次動作,MC1on 顯示 1,正轉 90 度

;第二次動作,MC1off,MC2on 顯示 2,正轉 90 度

;第三次動作,MC2off,MC3on 顯示 3,反轉 90 度

;第四次動作,MC3off,MC1on,MC2on,顯示 4

; 反轉 90 度,2 秒後,MC1off,MC2off

ORG 0H
SJMP BEGIN
;------------------------
ORG 30H
BEGIN: MOV SP,#07H
MOV P1,#C0H ;0
MOV P2,#00H ;RELAY OFF
MOV R4,#0H
;-----------------------
WAIT: JNB P0.3,BEGIN
OK: JNB P0.2,SURE
SJMP WAIT
;------------------------
SURE: MOV R5,#01H
ACALL DELAY
JNB P0.2,START
SJMP WAIT
;-----------------------
START: INC R4
CJNE R4,#01H,TWO
SJMP SUBB1
TWO: CJNE R4,#02H,THREE
SJMP SUBB2
THREE: CJNE R4,#03H,FOUR