from machine import Pin, PWM
import utime

MID = 1500000
MIN = 1000000
MAX = 2000000

led = Pin(25, Pin.OUT)
pwm = PWM(Pin(15))

pwm.freq(50)
pwm.duty_ns(MID)

led.value(0)
utime.sleep(5)

def turn(val, sleep_time = 2):
    pwm.duty_ns(val)
    led.value(1)
    utime.sleep(sleep_time)
    led.value(0)
    utime.sleep(2)

while True:
    turn(MIN)
    turn(MID)
    turn(MAX, 5)