Hi Melvin,

If you want to see the sequence 0123..89012.. when you turn the optocoder clockwise and the sequence 987..210987.. otherwise you must change your program like following.

ORG 0H
JMP MAIN
;
ORG 50H
MAIN: MOV P0,#0FFH ;SET PORT 0 AS INPUT
MOV R1,#10H ;
TOLSD: CALL DISPLAY ;Put digit to screen
GET00: MOV A,P0 ;
ANL A,#003H ;
CJNE A,#000H,GET00 ;
DIRECT: MOV A,P0 ;
ANL A,#003H ;
CJNE A,#001H,NEXT ;
CW: INC R1 ;Forward
CJNE R1,#01AH,PLUS ;
MOV R1,#010H ;
PLUS: JMP TOLCD ;
NEXT: CJNE A,#002H,DIRECT ;CHECK CHANNEL B = 1
CCW: CJNE R1,#010H,MINUS ;
MOV R1,#01AH ;
MINUS: DEC R1 ;Back direction
JMP TOLSD ;
;
DISPLAY: MOV P1,R1 ;
CALL DELAY ;
RET
;
DELAY: OV R5,#035H
F: OV R4,#007H
E: OV R3,#000H
D: JNZ R3,D
JNZ R4,E
JNZ R5,F
RET
END

Bye,

George