105 lines
3.7 KiB
Python
105 lines
3.7 KiB
Python
"""
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The MIT License (MIT)
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Copyright (c) 2018 Dave Astels
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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--------------------------------------------------------------------------------
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Debounce an input pin.
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"""
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import time
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import digitalio
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class Debouncer:
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"""Debounce an input pin"""
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DEBOUNCED_STATE = 0x01
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UNSTABLE_STATE = 0x02
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CHANGED_STATE = 0x04
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def __init__(self, pin, mode=None, interval=0.010):
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"""Make am instance.
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:param int pin: the pin (from board) to debounce
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:param int mode: digitalio.Pull.UP or .DOWN (default is no pull up/down)
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:param int interval: bounce threshold in seconds (default is 0.010, i.e. 10 milliseconds)
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"""
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self.state = 0x00
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self.pin = digitalio.DigitalInOut(pin)
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self.pin.direction = digitalio.Direction.INPUT
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if mode is not None:
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self.pin.pull = mode
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if self.pin.value:
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self.__set_state(Debouncer.DEBOUNCED_STATE | Debouncer.UNSTABLE_STATE)
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self.previous_time = 0
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if interval is None:
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self.interval = 0.010
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else:
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self.interval = interval
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def __set_state(self, bits):
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self.state |= bits
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def __unset_state(self, bits):
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self.state &= ~bits
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def __toggle_state(self, bits):
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self.state ^= bits
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def __get_state(self, bits):
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return (self.state & bits) != 0
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def update(self):
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"""Update the debouncer state. Must be called before using any of the properties below"""
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self.__unset_state(Debouncer.CHANGED_STATE)
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current_state = self.pin.value
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if current_state != self.__get_state(Debouncer.UNSTABLE_STATE):
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self.previous_time = time.monotonic()
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self.__toggle_state(Debouncer.UNSTABLE_STATE)
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else:
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if time.monotonic() - self.previous_time >= self.interval:
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if current_state != self.__get_state(Debouncer.DEBOUNCED_STATE):
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self.previous_time = time.monotonic()
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self.__toggle_state(Debouncer.DEBOUNCED_STATE)
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self.__set_state(Debouncer.CHANGED_STATE)
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@property
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def value(self):
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"""Return the current debounced value of the input."""
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return self.__get_state(Debouncer.DEBOUNCED_STATE)
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@property
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def rose(self):
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"""Return whether the debounced input went from low to high at the most recent update."""
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return self.__get_state(self.DEBOUNCED_STATE) and self.__get_state(self.CHANGED_STATE)
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@property
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def fell(self):
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"""Return whether the debounced input went from high to low at the most recent update."""
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return (not self.__get_state(self.DEBOUNCED_STATE)) and self.__get_state(self.CHANGED_STATE)
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