from machine import Pin, PWM
from time import sleep_ms, time_ns

###########################################################
#Servo:   horn angle depends on absolute PWM pulse duration 
#                                      (not relative duty!)
#         0,5 ms =  500 µs =   500.000 ns ==>   0 degrees
#         ...
#         2,5 ms = 2500 µs = 2.500.000 ns ==> 180 degrees
#PWM frequency may be adjusted from 40 Hz and 400 Hz,
#but not more than 400 Hz, 
#for T = 1/f at 400 Hz is exactly 2,5 ms (!!!!)
#which means a 100% duty setting 
#At higher frequencies behaviour is undefined.       
#----------------------------------------------------------
def set_angle(device, angle):
  while angle < 0:
    angle += 180
  while angle > 180:
    angle -= 180
  
  duty = int(500_000 + angle * 2_000_000 / 180)
  device.duty_ns(duty)
###########################################################

servo = PWM(Pin(0), freq=40)
servo.duty_ns(500_000)

while True:
  for i in range(180):
    print(f"{i} Grad")
    set_angle(servo, i)
    sleep_ms(50)
  for i in range(180, 0, -1):
    print(f"{i} Grad")
    set_angle(servo, i)
    sleep_ms(50)