from machine import Pin
from machine import PWM
from time import *
print('LED PWM input')
D1 = 3
led = Pin(D1, Pin.OUT)
led_pwm = PWM(led)
while True:
brightness_str = input('brightness (0 - 100): ')
brightness = int(int(brightness_str) * 1023 / 100)
led_pwm.duty( brightness )