onoff/gpio.py

   1 import os.path
   2
   3 from .common import OnoffDevice, ST_ACTIVE
   4
   5 def _write_file_value(path, content):
   6     with open(path, "w") as f:
   7         f.write(content)
   8
   9 class OnoffGPIO(OnoffDevice):
  10     """A GPIO."""
  11     def __init__(self, gpionumber, active_low=False):
  12         """
  13         @type gpionumber: int
  14         @param gpionumber: a Linux GPIO number. That includes a controller
  15                            offset if necessary.
  16         @type active_low: bool
  17         @param active_low: whether the GPIO should be inverted
  18         """
  19         OnoffDevice.__init__(self)
  20         self.current_state = 0
  21         basedir = "/sys/class/gpio"
  22         self.gpiodir = "%s/gpio%d" % (basedir, gpionumber)
  23         if not os.path.isdir(self.gpiodir):
  24             _write_file_value("%s/export" % basedir, "%d" % gpionumber)
  25         _write_file_value("%s/direction" % self.gpiodir, "out")
  26         _write_file_value("%s/active_low" % self.gpiodir, "%d" % active_low)
  27
  28     def _set_state(self, state):
  29         self.current_state = state
  30         _write_file_value("%s/value" % self.gpiodir,
  31                          "1" if self.current_state == ST_ACTIVE else "0")
  32         self.changestate(self.current_state)
  33
  34     @property
  35     def state(self):
  36         return self.current_state
  37
  38     def activate(self):
  39         self._set_state(ST_ACTIVE)
  40
  41     def deactivate(self):
  42         self._set_state(0)