src/adafruit_blinka/microcontroller/generic_linux/libgpiod_pin.py

   1 # SPDX-FileCopyrightText: 2021 Melissa LeBlanc-Williams for Adafruit Industries
   2 #
   3 # SPDX-License-Identifier: MIT
   4 """A Pin class for use with libgpiod."""
   5 try:
   6     import gpiod
   7 except ImportError:
   8     raise ImportError(
   9         "libgpiod Python bindings not found, please install and try again! See "
  10         "https://github.com/adafruit/Raspberry-Pi-Installer-Scripts/blob/master/libgpiod.sh"
  11     ) from ImportError
  12
  13
  14 class Pin:
  15     """Pins dont exist in CPython so...lets make our own!"""
  16
  17     IN = 0
  18     OUT = 1
  19     LOW = 0
  20     HIGH = 1
  21     PULL_NONE = 0
  22     PULL_UP = 1
  23     PULL_DOWN = 2
  24     _CONSUMER = "adafruit_blinka"
  25
  26     id = None
  27     _value = LOW
  28     _mode = IN
  29
  30     def __init__(self, pin_id):
  31         self.id = pin_id
  32         if isinstance(pin_id, tuple):
  33             self._num = int(pin_id[1])
  34             self._chip = gpiod.Chip(str(pin_id[0]), gpiod.Chip.OPEN_BY_NUMBER)
  35         else:
  36             self._num = int(pin_id)
  37             self._chip = gpiod.Chip("gpiochip0", gpiod.Chip.OPEN_BY_NAME)
  38         self._line = None
  39
  40     def __repr__(self):
  41         return str(self.id)
  42
  43     def __eq__(self, other):
  44         return self.id == other
  45
  46     def init(self, mode=IN, pull=None):
  47         """Initialize the Pin"""
  48         if not self._line:
  49             self._line = self._chip.get_line(int(self._num))
  50             # print("init line: ", self.id, self._line)
  51
  52         if mode is not None:
  53             if mode == self.IN:
  54                 flags = 0
  55                 if pull is not None:
  56                     if pull == self.PULL_UP:
  57                         raise NotImplementedError(
  58                             "Internal pullups not supported in libgpiod, "
  59                             "use physical resistor instead!"
  60                         )
  61                     if pull == self.PULL_DOWN:
  62                         raise NotImplementedError(
  63                             "Internal pulldowns not supported in libgpiod, "
  64                             "use physical resistor instead!"
  65                         )
  66                     raise RuntimeError("Invalid pull for pin: %s" % self.id)
  67
  68                 self._mode = self.IN
  69                 self._line.release()
  70                 self._line.request(
  71                     consumer=self._CONSUMER, type=gpiod.LINE_REQ_DIR_IN, flags=flags
  72                 )
  73
  74             elif mode == self.OUT:
  75                 if pull is not None:
  76                     raise RuntimeError("Cannot set pull resistor on output")
  77                 self._mode = self.OUT
  78                 self._line.release()
  79                 self._line.request(consumer=self._CONSUMER, type=gpiod.LINE_REQ_DIR_OUT)
  80
  81             else:
  82                 raise RuntimeError("Invalid mode for pin: %s" % self.id)
  83
  84     def value(self, val=None):
  85         """Set or return the Pin Value"""
  86         if val is None:
  87             return self._line.get_value()
  88
  89         if val in (self.LOW, self.HIGH):
  90             self._value = val
  91             self._line.set_value(val)
  92             return None
  93         raise RuntimeError("Invalid value for pin")