;***************************************************************************
;MCS-51 Microcontroller Development Board 
;Display Test program
;Circuit Description: 4 digit Common Cathode Display is driving by a 74164
;                     DsDat-p1.4;DsClk-p1.5;Gw-p1.0;Sw-p1.1;Bw-p1.2;Qw-p1.3
;***************************************************************************
xsdat bit p1.4    
xsclk bit p1.5    
gw    bit p1.0    
sw    bit p1.1    
bw    bit p1.2    
qw    bit p1.3    
sjgw  equ 30h     
sjsw  equ 31h
sjbw  equ 32h
sjqw  equ 33h
;--------------------------------
          mov sp,#40h
          mov p1,#0fh
          mov p0,#55h
main :    
          mov sjgw,#4   
          mov sjsw,#3   
          mov sjbw,#2   
          mov sjqw,#1   
          
abc:      lcall display  
          ljmp abc       


;************************************************************************
;74164 Display subroutine, use RS1=1,RS0=0
;---------------------------------------------------------
display:  PUSH ACC             
          push psw
          clr rs1
          setb rs0              
          mov dptr,#xstab    
          mov a,sjgw           
          movc a,@a+dptr       
          acall dsout          
          clr gw
          acall ds1ms          
          setb gw
          mov a,sjsw
          movc a,@a+dptr       
          acall dsout          
          clr sw
          acall ds1ms           
          setb sw        
          mov a,sjbw
          movc a,@a+dptr        
          acall dsout          
          clr bw
          acall ds1ms           
          setb bw 
          mov a,sjqw
          movc a,@a+dptr       
          acall dsout          
          clr qw
          acall ds1ms          
          setb qw
          pop psw
          POP ACC              
          ret                  
;---Display output----------
dsout:    
          MOV R0,#8            
dSLOOP:   RLC A                
          MOV xsdat,C          
          SETB xsclk          
          CLR xsclk
          DJNZ R0,dSLOOP
          RET         
;---Display delay ---------- 
ds1ms:    mov r1,#10
ds1lo:    mov r2,#100
          djnz r2,$
          djnz r1,ds1lo
          ret                  
;************************************************************************
;Display character (Common Cathode)
xstab:    DB  3FH,06H,5BH,4FH    ;"0","1","2","3"
          DB  66H,6DH,7DH,07H    ;"4","5","6","7"
          DB  7FH,6FH,77H,7cH    ;"8","9","A","B" 
          DB  39H,5eh,79h,71h    ;"C","D","E","F"

end