from machine import Pin,PWM
from time import sleep
pin = Pin(4,Pin.OUT)
servo_pwm = PWM(pin,freq=50,duty=0)
def rotate(servo_pwm,degree):
val = int(degree*0.54)+25
servo_pwm.duty(val)
while True:
rotate(servo_pwm,0)
sleep(1)
rotate(servo_pwm,180)
sleep(1)