View difference between Paste ID: DpwpxEfw and D9ABmmwD

 """
 Inspiriert von
 BitBastelei #398 - Die "Magie" hinter PWM (analogWrite, Timer, Preload, etc)
 https://www.youtube.com/watch?v=nf8MB7FkRaI
 
 """
 
 
 import math
 from collections import namedtuple
 
 
 class Frequency:
     def __init__(self, value):
         self.value = value
 
     def __float__(self):
         return float(self.value)
 
     def __index__(self):
         return int(self.value)
 
     def __str__(self):
         units = ("Hz", "kHz", "MHz")
         value = self.value
         for unit in units:
             if value < 1000:
                 break
             value /= 1000
         return f"{value:.3f} {unit}"
 
     def __repr__(self):
         return f"{self.__class__.__name__}({self.value})"
 
 
 def pwm_calc(freq, bits=8, board_freq=16_000_000):
     result = namedtuple(
         "Configuration",
         "board_freq scaled_freq prescaler count_bits count_start target_freq",
     )
     increments = 2 ** bits
     counter_max = increments - 1
 
     for prescaler in (2 ** n for n in range(11)):
         if (current_freq := board_freq / prescaler / increments) < freq:
             break
 
     # math.ceil aufrunden, math.floor abrunden
     offset = round(counter_max * current_freq / freq)
     resulting_freq = current_freq / offset * counter_max
     return result(
         Frequency(board_freq),
         Frequency(current_freq),
         prescaler,
         bits,
         counter_max - offset,
         Frequency(resulting_freq),
     )
 
 
 result = pwm_calc(420)
 print("Prescaler:", result.prescaler)
 print("Frequency:", result.target_freq)
 print("Counter-Start:", result.count_start)
 
 # Prescaler: 256
 # Frequency: 420.648 Hz
 # Counter-Start: 107