import machine
from machine import Pin
from machine import PWM
import time

pwmPin = PWM(Pin(1, Pin.OUT))
pwmPin.freq(50)

while True:
    pwmPin.duty(25)
    time.sleep(3)
    pwmPin.duty(76)
    time.sleep(3)
    pwmPin.duty(125)
    time.sleep(3)