src/adafruit_blinka/microcontroller/generic_linux/periphery_pin.py

   1 """A Pin class for use with periphery."""
   2 try:
   3     from periphery import GPIO
   4 except ImportError:
   5     raise ImportError(
   6         "Periphery Python bindings not found, please install and try again! "
   7         "Try running 'pip3 install python-periphery'"
   8     ) from ImportError
   9
  10
  11 class Pin:
  12     """Pins dont exist in CPython so...lets make our own!"""
  13
  14     IN = "in"
  15     OUT = "out"
  16     LOW = 0
  17     HIGH = 1
  18     PULL_NONE = 0
  19     PULL_UP = 1
  20     PULL_DOWN = 2
  21
  22     id = None
  23     _value = LOW
  24     _mode = IN
  25
  26     def __init__(self, pin_id):
  27         self.id = pin_id
  28         if isinstance(pin_id, tuple):
  29             self._num = int(pin_id[1])
  30             self._chippath = "/dev/gpiochip{}".format(pin_id[0])
  31         else:
  32             self._num = int(pin_id)
  33             self._chippath = "/dev/gpiochip0"
  34         self._line = None
  35
  36     def __repr__(self):
  37         return str(self.id)
  38
  39     def __eq__(self, other):
  40         return self.id == other
  41
  42     def init(self, mode=IN, pull=None):
  43         """Initialize the Pin"""
  44         if mode is not None:
  45             if mode == self.IN:
  46                 self._mode = self.IN
  47                 if self._line is not None:
  48                     self._line.close()
  49                 self._line = GPIO(self._chippath, int(self._num), self.IN)
  50             elif mode == self.OUT:
  51                 self._mode = self.OUT
  52                 if self._line is not None:
  53                     self._line.close()
  54                 self._line = GPIO(self._chippath, int(self._num), self.OUT)
  55             else:
  56                 raise RuntimeError("Invalid mode for pin: %s" % self.id)
  57
  58             if pull is not None:
  59                 if pull == self.PULL_UP:
  60                     raise NotImplementedError(
  61                         "Internal pullups not supported in periphery, "
  62                         "use physical resistor instead!"
  63                     )
  64                 if pull == self.PULL_DOWN:
  65                     raise NotImplementedError(
  66                         "Internal pulldowns not supported in periphery, "
  67                         "use physical resistor instead!"
  68                     )
  69                 raise RuntimeError("Invalid pull for pin: %s" % self.id)
  70
  71     def value(self, val=None):
  72         """Set or return the Pin Value"""
  73         if val is not None:
  74             if val == self.LOW:
  75                 self._value = val
  76                 self._line.write(False)
  77                 return None
  78             if val == self.HIGH:
  79                 self._value = val
  80                 self._line.write(True)
  81                 return None
  82             raise RuntimeError("Invalid value for pin")
  83         return self.HIGH if self._line.read() else self.LOW