from machine import Pin, PWM
from time import sleep

pwm = PWM(Pin(15))

pwm.freq(1000)

while True:
    for duty in range(65025):
		pwm.duty_u16(duty)
		sleep(0.0001)
	for duty in range(65025, 0, -1):
		pwm.duty_u16(duty)
		sleep(0.0001)