src/adafruit_blinka/microcontroller/generic_linux/libgpiod_pin.py

   1 """A Pin class for use with libgpiod."""
   2 try:
   3     import gpiod
   4 except ImportError:
   5     raise ImportError(
   6         "libgpiod Python bindings not found, please install and try again! See "
   7         "https://github.com/adafruit/Raspberry-Pi-Installer-Scripts/blob/master/libgpiod.sh"
   8     )
   9
  10
  11 class Pin:
  12     """Pins dont exist in CPython so...lets make our own!"""
  13
  14     IN = 0
  15     OUT = 1
  16     LOW = 0
  17     HIGH = 1
  18     PULL_NONE = 0
  19     PULL_UP = 1
  20     PULL_DOWN = 2
  21     _CONSUMER = "adafruit_blinka"
  22
  23     id = None
  24     _value = LOW
  25     _mode = IN
  26
  27     def __init__(self, pin_id):
  28         self.id = pin_id
  29         if isinstance(pin_id, tuple):
  30             self._num = int(pin_id[1])
  31             self._chip = gpiod.Chip(str(pin_id[0]), gpiod.Chip.OPEN_BY_NUMBER)
  32         else:
  33             self._num = int(pin_id)
  34             self._chip = gpiod.Chip("gpiochip0", gpiod.Chip.OPEN_BY_NAME)
  35         self._line = None
  36
  37     def __repr__(self):
  38         return str(self.id)
  39
  40     def __eq__(self, other):
  41         return self.id == other
  42
  43     def init(self, mode=IN, pull=None):
  44         """Initialize the Pin"""
  45         if not self._line:
  46             self._line = self._chip.get_line(int(self._num))
  47             # print("init line: ", self.id, self._line)
  48
  49         if mode is not None:
  50             if mode == self.IN:
  51                 flags = 0
  52                 if pull is not None:
  53                     if pull == self.PULL_UP:
  54                         raise NotImplementedError(
  55                             "Internal pullups not supported in libgpiod, "
  56                             "use physical resistor instead!"
  57                         )
  58                     if pull == self.PULL_DOWN:
  59                         raise NotImplementedError(
  60                             "Internal pulldowns not supported in libgpiod, "
  61                             "use physical resistor instead!"
  62                         )
  63                     raise RuntimeError("Invalid pull for pin: %s" % self.id)
  64
  65                 self._mode = self.IN
  66                 self._line.release()
  67                 self._line.request(
  68                     consumer=self._CONSUMER, type=gpiod.LINE_REQ_DIR_IN, flags=flags
  69                 )
  70
  71             elif mode == self.OUT:
  72                 if pull is not None:
  73                     raise RuntimeError("Cannot set pull resistor on output")
  74                 self._mode = self.OUT
  75                 self._line.release()
  76                 self._line.request(consumer=self._CONSUMER, type=gpiod.LINE_REQ_DIR_OUT)
  77
  78             else:
  79                 raise RuntimeError("Invalid mode for pin: %s" % self.id)
  80
  81     def value(self, val=None):
  82         """Set or return the Pin Value"""
  83         if val is None:
  84             return self._line.get_value()
  85
  86         if val in (self.LOW, self.HIGH):
  87             self._value = val
  88             self._line.set_value(val)
  89             return None
  90         raise RuntimeError("Invalid value for pin")