ORG 000H
START: SJMP START1
ORG 050H
START1:
BACK:  
        ACALL _45DEG          
        SJMP BACK             

_45DEG:  SETB P1.0
        MOV R2, #22             ;22 cycles for 1ms
_ABC1:  NOP                    
        NOP                   
        DJNZ R2, _ABC1        
        CLR P1.0
        ACALL DELAY_20MS       
        RET                    
DELAY_20MS: MOV R0,#4607     ;4607 cycles for 20 ms             
_ABCD:  NOP
        NOP
        DJNZ R0, _ABCD
        RET