1  # SPDX-FileCopyrightText: 2019 Anne Barela for Adafruit Industries
 2  #
 3  # SPDX-License-Identifier: MIT
 4  
 5  import board
 6  import storage
 7  from analogio import AnalogIn
 8  
 9  def read_buttons():
10      with AnalogIn(board.A3) as ain:
11          reading = ain.value / 65535
12          if reading > 0.75:
13              return None
14          if reading > 0.4:
15              return 4
16          if reading > 0.25:
17              return 3
18          if reading > 0.13:
19              return 2
20          return 1
21  
22  readonly = True
23  # if a button is pressed while booting up, CircuitPython can write to the drive
24  button = read_buttons()
25  if button != None:
26      readonly = False
27  if readonly:
28      print("OS has write access to CircuitPython drive")
29  else:
30      print("CircuitPython has write access to drive")
31  storage.remount("/", readonly)