15.3.1

第十五章 C51单片机软件抗干扰和数字滤波

1限幅滤波
FILTTER1:
MOV 	B,A
CLR		C
SUBB 	A,SDAT						
 JNC   	FTLTER1
CPL    	A
INC    	A
JUGFT1:
SETB	A
SUBB	A,#DELTY						
JNC 		JUGFT3
MOV	A,SDAT
RET
JUGFT3:
MOV    	A,B
MOV    	SDAT,A    
RET
2限速滤波
FILTER2:
MOV 	A,20H				
CLR 	C					
SUBB 	A,21H				 
JNC 		LOOP0
CPL A
INC A
LOOP0:						
MOV 	23H,A				
MOV 	A,21H				
CLR 	C
SUBB 	A,22H
JNC 		LOOP1
CPL 		A
INC 		A
LOOP1
MOV 	24H，A				
ADD 	A,23H
RRC 	A					 
MOV 	LIMIT,A
MOV 	A,23H
CJNE	A,LIMIT,DONE1
AJMP 	DONE3				
DONEl:
JC 		DONE3				
MOV 	A,24H
CJNE 	A,LIMIT, DONE2		
AJMP 	DONE3				
DONE2:						
JC 		DONE3
AJMP 	DONE4
DONE3:						 
MOV 	A,22H
AJMP 	DONE5
DONE4:						 
MOV 	A,21H
ADD 	A,22H
RRC 	A
AJMP 	DONE5
DONE5:						 
MOV	A,21H
DONE6:
RET
LIMIT:
EQU 30H