from machine import Timer, Pin, PWM

def tim(x):
    global i, direc
    pwm.duty(lista[i])
    if direc == 0:
        i = i + 1
        if i > 4:
            i = 0

    else:
        i = i - 1
        if i < 0:
            i = 4


def itr (x):
    global direc
    direc = not direc

def velocidad(x):
    global vel, t0

    if vel == 250:
        vel = 500
    else:
        vel = 250

    t0.init(period=vel, mode=Timer.PERIODIC, callback=tim)

pwm = PWM(Pin(23), freq=50)
t0 = Timer(0)
t0.init(period=250, mode=Timer.PERIODIC, callback=tim)
lista = [25, 50, 75, 100, 125]
push = Pin(12,Pin.IN, Pin.PULL_UP)
push.irq(trigger=Pin.IRQ_FALLING, handler=itr)
push_2 = Pin(14,Pin.IN, Pin.PULL_UP)
push_2.irq(trigger=Pin.IRQ_FALLING, handler=velocidad)
direc = 0
i = 0
vel = 250

while(1):
    pass