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Debounced switch using pin and timer IRQs on MicroPython
#
# inspired by: https://forum.micropython.org/viewtopic.php?t=1938#p10931
#
import micropython
try:
from machine import Timer
timer_init = lambda t, p, cb: t.init(period=p, callback=cb)
except ImportError:
from pyb import Timer
timer_init = lambda t, p, cb: t.init(freq=1000 // p, callback=cb)
# uncomment when debugging callback problems
#micropython.alloc_emergency_exception_buf(100)
class DebouncedSwitch:
def __init__(self, sw, cb, arg=None, delay=50, tid=4):
self.sw = sw
# Create references to bound methods beforehand
# http://docs.micropython.org/en/latest/pyboard/library/micropython.html#micropython.schedule
self._sw_cb = self.sw_cb
self._tim_cb = self.tim_cb
self._set_cb = getattr(self.sw, 'callback', None) or self.sw.irq
self.delay = delay
self.tim = Timer(tid)
self.callback(cb, arg)
def sw_cb(self, pin=None):
self._set_cb(None)
timer_init(self.tim, self.delay, self._tim_cb)
def tim_cb(self, tim):
tim.deinit()
if self.sw():
micropython.schedule(self.cb, self.arg)
self._set_cb(self._sw_cb if self.cb else None)
def callback(self, cb, arg=None):
self.tim.deinit()
self.cb = cb
self.arg = arg
self._set_cb(self._sw_cb if cb else None)
def test_pyb(ledno=1):
import pyb
sw = pyb.Switch()
led = pyb.LED(ledno)
return DebouncedSwitch(sw, lambda l: l.toggle(), led)
def test_machine(swpin=2, ledpin=16):
from machine import Pin
sw = Pin(swpin, Pin.IN)
led = Pin(ledpin, Pin.OUT)
return DebouncedSwitch(sw, lambda l: l.value(not l.value()), led)
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