from machine import Pin
from time import sleep

Ap=Pin(4,Pin.OUT,0)
An=Pin(5,Pin.OUT,0)
Bp=Pin(2,Pin.OUT,0)
Bn=Pin(15,Pin.OUT,0)

delay=1
for i in range(50):
    Bn.value(0)
    Ap.value(1)
    sleep(delay)
    Ap.value(0)
    Bp.value(1)
    sleep(delay)
    Bp.value(0)
    Ap.value(1)
    sleep(delay)
    An.value(0)
    Bn.value(1)
    sleep(delay)