from machine import Pin
from neopixel import NeoPixel
from time import *

print('NeoPixel LED + button  Example')

# button input on pin 2:
btn = Pin(2, Pin.IN, Pin.PULL_UP)
btn_val_last = 1

# create NeoPixel driver on pin 13 for 16 pixel:
np = NeoPixel(Pin(13), 16)

print('begin with white color for 2 seconds..')
for i in range(16):
  np[i] = (255, 255, 255) 

# write data to all pixels:
np.write()  

# delay 2 seconds:
sleep_ms(2000)

program_state = 'START'
print('start fading green color up and down..')

while True:

  #print('btn =', btn.value())
  # check that the button changed from high to low:
  if btn.value() == 0:  # button value is low
    if btn_val_last == 1:  # last button value was high
      # program state transitions between START and STOP states:
      if program_state == 'START':
        program_state = 'STOP'
      elif program_state == 'STOP':
        program_state = 'START'
      print('program_state =', program_state)
  # update the last button value:
  btn_val_last = btn.value()

  # program behaviors for START and STOP states:
  if program_state == 'STOP':
    # set all pixels to red color during STOP state:
    for i in range(16):
      np[i] = (255, 0, 0)
    np.write()
    sleep_ms(100)
  elif program_state == 'START':
    # fade green color up and down during START state:
    for g in range(100):
      for i in range(16):
        np[i] = (0, g, 0)
      np.write()
      sleep_ms(1)
    for g in range(100):
      for i in range(16):
        np[i] = (0, 100-g, 0)
      np.write()
      sleep_ms(1)