from machine import Pin
from time import sleep

A1=Pin(17,Pin.OUT)
B1=Pin(5,Pin.OUT)
A2=Pin(16,Pin.OUT)
B2=Pin(4,Pin.OUT)

def pasos(x):
  A1.value(int(x[0]))
  B1.value(int(x[1]))
  A2.value(int(x[2]))
  B2.value(int(x[3]))

def isrA(pin):
  global cnt
  if (canal_B.value()==0):
    cnt += 1
    if cnt >= 3:
      cnt=0
    while(canal_A.value()==0):
      sleep(0.001)

def isrB(pin):
  global cnt
  if (canal_A.value()==0):
    cnt -=1
    if cnt <= 0:
      cnt=3
    while(canal_B.value()==0):
      sleep(0.001)


canal_A=Pin(12,Pin.IN)
canal_A.irq(trigger=Pin.IRQ_FALLING,handler=isrA)
canal_B=Pin(13,Pin.IN)
canal_B.irq(trigger=Pin.IRQ_FALLING,handler=isrB)

cnt=0

lista=["1100","0110","0011","1001"]

while(1):
  pasos(lista[cnt])