from machine import Pin
from rp2 import PIO, StateMachine, asm_pio
@asm_pio(set_init=(rp2.PIO.OUT_LOW,)*4)
def stepper():
    label("start")
    set(pins, 8)
    set(x, 31) [6]
    label("delay1")
    nop() [29]
    jmp(x_dec, "delay1") 
    set(pins, 2)
    set(x, 31) [6]
    label("delay2")
    nop() [29]
    jmp(x_dec, "delay2") 
    set(pins, 4)
    set(x, 31) [6]
    label("delay3")
    nop() [29]
    jmp(x_dec, "delay3") 
    set(pins, 1)
    set(x, 31) [6]
    label("delay4")
    nop() [29]
    jmp(x_dec, "delay4") 
sm = StateMachine(0, stepper, freq=2000, set_base=Pin(0))
sm.active(1)
sm.put(1)