from machine import Pin, ADC
from time import sleep

class BusOut:
  def __init__(self, *pins):
    self.pins = [ Pin(pin, Pin.OUT) for pin in pins ]
    self.value = 0

  def write(self, value):
    self.value = value
    for i, pin in enumerate(self.pins):
      pin.value((value >> i) & 1)

  def read(self):
    return self.value

class Potentiometer:
  def __init__(self, pin, a = 0, b = 3.3):
    self.pin = ADC(Pin(pin, Pin.IN))
    self.a = a
    self.b = b

  def read(self):
    return (self.b - self.a) * self.pin.read_u16() / 65535 + self.a

leds = BusOut(4, 5, 6, 7, 8, 9, 10, 11)
seconds = Potentiometer(28, 0.1, 2)

while True:
  i = 1
  while i != 256:
    leds.write(i)
    sleep(seconds.read())
    i = i * 2

  leds.write(255)
  sleep(seconds.read())

  i = 128
  while i != 0:
    leds.write(i - 1)
    sleep(seconds.read())
    i = i // 2

  leds.write(0)
  sleep(seconds.read())