import time
from machine import Pin,PWM

servo = PWM(Pin(0, Pin.OUT))
servo.freq(50)

while True:
    for i in range(1000,9000):
        servo.duty_u16(i)
    time.sleep(1.5)
    for i in range(9000,1000,-1):
        servo.duty_u16(i)
    time.sleep(1.5)