1  """Maps acceleration (tilt) to Neopixel colors.
 2  
 3  x, y, and z acceleration components map to red, green and blue,
 4  respectively.
 5  
 6  When the CPX is level, the lights are blue because there is no acceleration
 7  on x or y, but on z, gravity pulls at 9.81 meters per second per second (m/s²).
 8  When banking, the vertical (z) axis is no longer directly aligned with gravity,
 9  so the blue decreases, and red increases because gravity is now pulling more
10  along the x axis. Similarly, when changing the pitch from level, we see blue change
11  to green.
12  
13  This video walks you through the code: https://youtu.be/eNpPLbYx-iA
14  """
15  
16  import time
17  from adafruit_circuitplayground.express import cpx
18  
19  cpx.pixels.brightness = 0.2  # Adjust overall brightness as desired, between 0 and 1
20  
21  
22  def color_amount(accel_component):
23      """Convert acceleration component (x, y, or z) to color amount (r, g, or b)"""
24      standard_gravity = 9.81  # Acceleration (m/s²) due to gravity at the earth’s surface
25      accel_magnitude = abs(accel_component)                      # Ignore the direction
26      constrained_accel = min(accel_magnitude, standard_gravity)  # Constrain values
27      normalized_accel = constrained_accel / standard_gravity     # Convert to 0–1
28      return round(normalized_accel * 255)                        # Convert to 0–255
29  
30  
31  def format_acceleration():
32      return ', '.join(('{:>6.2f}'.format(axis_value) for axis_value in acceleration))
33  
34  
35  def format_rgb():
36      return ', '.join(('{:>3d}'.format(rgb_amount) for rgb_amount in rgb_amounts))
37  
38  
39  def log_values():
40      print('({}) ==> ({})'.format(format_acceleration(), format_rgb()))
41  
42  
43  while True:
44      acceleration = cpx.acceleration
45      rgb_amounts = [color_amount(axis_value) for axis_value in acceleration]
46      cpx.pixels.fill(rgb_amounts)
47      log_values()
48      time.sleep(0.1)