12.3.4定时器计数器0工作在模式3方式.txt

<mcs-51单片机应用开发实用子程序>书上的程序

ORG 	00H
RESET:
LJMP 	START
ORG		0BH							
COUNT10:
LJMP 	COUNTO						
ORG 1BH
COUNT11:
LJMP 	COUNT1
ORG 	30H							
START:
MOV 	SP,#50H						
MOV 	A,TMOD
ANL 	A,#11110000B
ORL 	A,#00000011B					
MOV 	TMOD,A						
MOV 	TH0#(256-100)
MOV 	TL0,#(256-200)
CLR 	TF0
CLR 	TF1
SETB 	IE.1							
SETB 	IE.3							
SETB 	IE.7
SETB 	TR0
SETB 	TR1
CLR 	P3.5							
CLR 	P3.4
L1:
NOP
JMP 		L1
COUNTO:
CLR 	IE.1
CPL 		P3.5							
MOV 	TL0,#(256-200)
SETB 	IE.1
RETI 
COUNT1:
CLR		IE.3							
CPL		P3.4							
MOV 	TH0,#(256-100)
SETB 	IE.3
RETI
END