text: # SPDX-FileCopyrightText: 2017 John Park for Adafruit Industries
  #
  # SPDX-License-Identifier: MIT
  
  """
  UFO Flying Saucer with Circuit Playground Express
  https://learn.adafruit.com/ufo-circuit-playground-express/
  Plays UFO lights and sounds if the board is upside down only,
  Tilt to change light color, cycle speed, tone pitch
  """
  
  import time
  
  from adafruit_circuitplayground.express import cpx
  
  def simple_circle(wait, red, green, blue):
      """timing, color values per channel"""
      baseFreq = int(20 + (green * 0.3))  # tone value derived from rotation
  
      for i in range(10):
          cpx.pixels[i] = ((0, 0, 0))
          cpx.start_tone(baseFreq + i)  # increasing pitch sweep
          time.sleep(wait)
  
      for i in range(10):
          cpx.pixels[i] = ((red, green, blue))
          time.sleep(wait)
  
  
  # Main loop gets x, y and z axis acceleration, prints the values, and turns on
  # lights if the UFO is upside down, plays tones
  while True:
      R = 0
      G = 0
      B = 0
      x, y, z = cpx.acceleration  # read the accelerometer values
  
      R = 10 * (R + abs(int(x)))  # scale up the accel values into color values
      G = 10 * (G + abs(int(y)))
      B = 10 * (B + abs(int(z)))
  
      # check for upside down state on z axis
      if z < 0:  # any negative number on z axis means it's upside down enough
          speed = (0.01 * (B * 0.025))
          simple_circle(speed, R, G, B)  # speed based on tilt, .01 is good start
  
      else:  # right side up means no colors or sound!
          cpx.pixels.fill((0, 0, 0))
          cpx.stop_tone()
  