from machine import Pin, PWM
import time
import math
led = PWM(Pin(16), freq=1000, duty=0)
def pulse(l, t):
    
 for i in range(20):
    l.duty(int(math.sin(i / 10 * math.pi) * 500 + 500))
    time.sleep_ms(t)
while True:
 pulse(led, 50)
 time.sleep(1)
 for i in range(10):
    pulse(led, 20)