f=10KHz -> T=10000us -> MC = 5000(thạch anh 6MHz) -> tH = 2000MC + tL = 3000MC  (40%) 
ORG 0000H 
LOOP:  	SET P1.7 
 	 	ACALL DELAY2000MC 
 	 	CLR P1.3 
 	 	ACALL DELAY3000MC 
 	 	SJMP LOOP 
DELAY2000MC: 
 	 	MOV R7,#10
 	 	DJNZ R7,$ 
RET 
DELAY3000MC: 
 	 	MOV R7,#15 
 	 	DJNZ R7,$ 
RET 
END