micropython-examples/pwm/led.py

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

led = PWM(Pin(0, Pin.OUT))

for i in range(-1, 1024, 8):
    led.duty(i)
    print(i)
    sleep(0.1)
    
for i in range(1023, -1, -8):
    led.duty(i)
    print(i)
    sleep(0.1)