The stepper motor has five wires, one of those is the common, and remaining 4 wires are line 1 to 4. Each of this is connected to P1.0, P1.1, P1.2 and P1.4

Figure 1. Circuit of stepper motor driver

$mod51

            org 00h

            jmp mulai

mulai:

            mov r0, #55

ulang1: 

            mov p1, #00001000b

            call tunda

            mov p1, #00000100b

            call tunda

            mov p1, #00000010b

            call tunda

            mov p1, #00000001b

            call tunda

            djnz r0, ulang1

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

            mov r0, #55

ulang2:

            mov p1, #00000001b

            call tunda

            mov p1, #00000010b

            call tunda

            mov p1, #00000100b

            call tunda

            mov p1, #00001000b

            call tunda

            djnz r0, ulang2

            jmp mulai

tunda:  mov r4, #20

maning: mov r5, #255

kurang: dec r5

            cjne r5, #00h, kurang

            djnz r4, maning

            ret

end