primitives/switch.py

   1 # switch.py
   2
   3 # Copyright (c) 2018-2022 Peter Hinch
   4 # Released under the MIT License (MIT) - see LICENSE file
   5
   6 import uasyncio as asyncio
   7 import utime as time
   8 from . import launch
   9
  10 class Switch:
  11     debounce_ms = 50
  12     def __init__(self, pin):
  13         self.pin = pin # Should be initialised for input with pullup
  14         self._open_func = False
  15         self._close_func = False
  16         self.switchstate = self.pin.value()  # Get initial state
  17         self._run = asyncio.create_task(self.switchcheck())  # Thread runs forever
  18
  19     def open_func(self, func, args=()):
  20         if func is None:
  21             self.open = asyncio.Event()
  22         self._open_func = self.open.set if func is None else func
  23         self._open_args = args
  24
  25     def close_func(self, func, args=()):
  26         if func is None:
  27             self.close = asyncio.Event()
  28         self._close_func = self.close.set if func is None else func
  29         self._close_args = args
  30
  31     # Return current state of switch (0 = pressed)
  32     def __call__(self):
  33         return self.switchstate
  34
  35     async def switchcheck(self):
  36         while True:
  37             state = self.pin.value()
  38             if state != self.switchstate:
  39                 # State has changed: act on it now.
  40                 self.switchstate = state
  41                 if state == 0 and self._close_func:
  42                     launch(self._close_func, self._close_args)
  43                 elif state == 1 and self._open_func:
  44                     launch(self._open_func, self._open_args)
  45             # Ignore further state changes until switch has settled
  46             await asyncio.sleep_ms(Switch.debounce_ms)
  47
  48     def deinit(self):
  49         self._run.cancel()