from machine import Pin, PWM
import time
servo = PWM(Pin(15), freq = 50)
def set_angle(angle):
    min_duty = 500000
    max_duty = 2500000
    duty = min_duty + (angle/180)*(max_duty - min_duty)
    servo.duty_ns(int(duty))
while True:
    set_angle(0)
    time.sleep(1)
    set_angle(90)
    time.sleep(1)
    set_angle(180)
    time.sleep(1)