from machine import Pin, PWM
from time import sleep

s1= PWM(Pin(23), freq=50)
s2= PWM(Pin(22), freq=50)
s3= PWM(Pin(21), freq=50)
s4= PWM(Pin(19), freq=50)
btn=Pin(2,Pin.IN,Pin.PULL_UP)
lista=[25,50,80,125]
k=0

while(1):
  if (btn.value()==0):
    k=k+1
    if k==4:
      k=0

  if k==0:
    for i in lista:
      s1.duty(i)
      sleep(0.5)

  if k==1:
    for i in lista:
      s2.duty(i)
      sleep(0.5)

  if k==2:
    for i in lista:
      s3.duty(i)
      sleep(0.5)

  if k==3:
    for i in lista:
      s4.duty(i)
      sleep(0.5)