51單片機STC89C52 DA數模轉換

CSDA BIT P3.2
WRR BIT P3.6
WELA BIT P2.7
DULA BIT P2.6

ORG 0000H
LOOP0:
MOV P0,#0FFH ;關數碼管顯示
SETB WELA
CLR WELA
CLR DULA
SETB CSDA
SETB WR
MOV A,#0
LOOP1:
MOV P0,A
CLR CSDA 
CLR WRR
LCALL DELAY
SETB WRR
SETB CSDA
INC A
SJMP LOOP1
DELAY:    ;延時 
SETB RS1
MOV R2,#04H
DELAY2:
MOV R1,#10
DELAY1:
MOV R0,#250
DELAY0:
NOP
NOP 
DJNZ R0,DELAY0
DJNZ R1,DELAY1
//DJNZ R2,DELAY2
CLR RS1
RET
END