max501pot.txt

采用MAX501DA转换器件

;*************DAC-POT**********************
  ;******采用DA 变换器做数字电位器***********
  ;TIM CAI  2007-06-21



      DA_LADAC          EQU     P1.0
      DA_SET       	EQU     P1.1
      DA_CLR           	EQU     P1.2
      UP         	EQU     P1.3
      DOWN 		EQU 	P1.4
      DA_CSMSB 		EQU 	P1.5
      DA_WR 		EQU 	P1.6
      DA_CSLSB 		EQU 	P1.7

      DL           EQU     	30H
      DH           EQU     	31H
       		
  
      		ORG 0000H
  	   	LJMP MAIN 



 ;-----------------主程序-----------------------
           	ORG 500H
 MAIN:     	MOV SP,#60H
	          
                          
           	MOV DH,#00H               
           	MOV DL,#00H                  


           	CLR  PSW.4
           	CLR  PSW.3                 
           	

                MOV R0,#00H
                MOV R1,#00H
                LCALL DAPOT
	   

   LOOP:  	SETB UP            
           	MOV C,UP           
           	JNC INC0
           	 
           	
           	           
       L1:   	SETB DOWN          
           	MOV C,DOWN        
           	JNC DEC0         
           	
        L2:   	LJMP LOOP          
  
   INC0:	LJMP INC1
   DEC0:	LJMP DEC1	 
  
	 ;加1
   INC1: 	MOV R0,DL
	   	MOV A,DH
	   	ANL A,#0FH
	   	MOV R1,A

	   	CJNE R1,#0FH,S1
	   	CJNE R0,#0FFH,S1   
   	   	LJMP S2
   	   	
   	   	          
     S1:	MOV A,R0           
	   	ADD A,#01H              
	   	MOV R0,A             
	   	MOV A,R1             
	   	ADDC A,#00H          
	   	MOV R1,A  
	   	MOV DL,R0
	   	MOV DH,R1             
	   	LCALL DAPOT
	   	         
  
     S2:	LJMP  L1
	
	
               
;减1
      DEC1:	MOV R0,DL         
	 	MOV A,DH
	 	ANL A,#0FH
	 	MOV R1,A 
	        CJNE  R1,#00H,S3 
	 	CJNE  R0,#00H,S3            
	 	LJMP S6                  
       S3:  	MOV A,R0                       
      		JZ S5                      
      		DEC R0                        
     		LJMP S4                   
       S5:	MOV A,R1
		JZ S6                    
		DEC R1                       
		MOV R0,#0FFH 

        S4:	MOV DL,R0
		MOV DH,R1                  	                   
		LCALL DAPOT

	S6:	LJMP L2

                       

                                 
          


   ;---------------------DA 控制子程序-----------------------
  ;入口：DH，DL
  ;出口：DA转换器
     DAPOT:	SETB DA_LADAC
	        SETB DA_SET
	        SETB DA_CLR
	        SETB DA_CSMSB
	        CLR DA_CSLSB
	        CLR DA_WR
	        NOP
	        NOP
	        NOP
	        NOP
	        MOV P0,R0
	        NOP
	        NOP
	        NOP
	        SETB DA_WR
	        NOP
	        NOP
	        NOP
	        SETB DA_CSLSB
	        NOP
	        NOP
	        NOP
                CLR DA_CSMSB
                NOP
                NOP
                CLR DA_WR
                NOP
                NOP
                NOP
                MOV P0,R1
                NOP
                NOP
                NOP
                SETB DA_WR
                NOP
                NOP
                NOP
                SETB DA_CSMSB
                NOP
                NOP
                NOP
                CLR DA_LADAC
                NOP
                NOP
                NOP
                SETB DA_LADAC
                CALL DELAY
                RET

	                  
 
    DELAY:	MOV R4,#08H 
    DELAY1:     MOV R3,#0FFH
    DELAY2:	DJNZ R3,DELAY2 
    		DJNZ R4,DELAY1         
           	RET
 
 
    		
	   

  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
           END