Source code for grove.button.button_gpio

#!/usr/bin/env python
#
# This is the library for Grove Base Hat which used to connect gpio-type button.
#

'''
## License

The MIT License (MIT)

Grove Base Hat for the Raspberry Pi, used to connect grove sensors.
Copyright (C) 2018  Seeed Technology Co.,Ltd. 

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
'''
from __future__ import division
import time
import threading
from grove.button import Button
from grove.gpio import GPIO

_CYCLE_PERIOD    = 0.02   # 20 ms
_SINGLE_KEY_TM   = 0.03   # 30 ms
_KEY_INTERVAL    = 0.3    # 300 ms
_LONG_KEY_TM     = 2.0    # 2s

class ButtonTypedGpio(Button):
    # all key states in FSM
    KEY_STATE_IDLE    = 0
    KEY_STATE_DOWN    = 1
    KEY_STATE_ONESHOT = 2
    KEY_STATE_LONG    = 3

    def __init__(self, pin, low_pressed = True):
        super(ButtonTypedGpio, self).__init__(pin)

        self.__low_press = low_pressed

        self.__state = self.KEY_STATE_IDLE
        self.__duration = 0.0
        self.__distance = _KEY_INTERVAL
        self.__thrd_exit = False
        self.__thrd = None

        self.__gpio = GPIO(pin, GPIO.IN)
        self.__gpio.on_event = self.__gpio_event

        if self.__thrd is None or not self.__thrd.is_alive():
            self.__thrd = threading.Thread( \
                    target = ButtonTypedGpio.__thrd_chk_evt, \
                    args = (self,))
            self.__thrd.setDaemon(True)
            self.__thrd.start()

    def __del__(self):
        self.__thrd_exit = True
        while self.__thrd.isAlive():
            time.sleep(_CYCLE_PERIOD / _CYCLE_UNIT)
        self.__thrd.join()

    def is_pressed(self):
        v = self.__gpio.read()
        return self.__low_press != bool(v)

    # called by GPIO library
    def __gpio_event(self, pin, value):
        press = self.is_pressed()
        tm = time.time()
        self._send_event(self.EV_LEVEL_CHANGED, press, tm)

    # key event FSM(finite state machine)
    def __key_evt_fsm(self, dt):
        r = 0
        press = self.is_pressed()
        self.__distance = self.__distance + dt

        if self.__state == self.KEY_STATE_IDLE:
            if press:
                self.__duration = 0.0
                self.__state = self.KEY_STATE_DOWN
        elif self.__state == self.KEY_STATE_DOWN:
            if press:
                self.__duration = self.__duration + dt
                if self.__duration >= _SINGLE_KEY_TM:
                    self.__state = self.KEY_STATE_ONESHOT
        elif self.__state == self.KEY_STATE_ONESHOT:
            if not press:
                # print("distance {}".format(self.__distance))
                if self.__distance >= _KEY_INTERVAL:
                    r = self.EV_SINGLE_CLICK
                else:
                    r = self.EV_DOUBLE_CLICK
            else:
                self.__duration = self.__duration + dt
                # print("duration {}".format(self.__duration))
                if self.__duration >= _LONG_KEY_TM:
                    r = self.EV_LONG_PRESS
                    self.__state = self.KEY_STATE_LONG
        elif self.__state == self.KEY_STATE_LONG:
            if not press:
                self.__distance = _KEY_INTERVAL

        if not press:
            self.__state = self.KEY_STATE_IDLE

        if r == self.EV_DOUBLE_CLICK:
            self.__distance = _KEY_INTERVAL
        elif r == self.EV_SINGLE_CLICK:
            self.__distance = 0.0

        return r, press


    # Thread to check events
    def __thrd_chk_evt(self):
        '''
        # prevent dither
        time.sleep(0.01)
        v = self.__gpio.read()
        if self.__low_press == bool(v):
            return
        '''
        self.__last_time = time.time();
        while not self.__thrd_exit:
        # or self.__state != self.KEY_STATE_IDLE:
            t = time.time()
            dt, self.__last_time = t - self.__last_time, t

            r, pressed = self.__key_evt_fsm(dt)
            if r:
                self._send_event(r, pressed, t)
            time.sleep(_CYCLE_PERIOD)