switchdebounce.py

import machine
from machine import Timer
# see listing one
# https://www.embedded.com/electronics-blogs/break-points/4024981/My-favorite-software-debouncers

np = machine.Neopixel(15,8,machine.Neopixel.TYPE_RGB)

button = machine.Pin(34,machine.Pin.IN)

check_msec = 20
press_msec = 10
release_msec = 100
count = release_msec / check_msec

RawKeyPressed = False
DebouncedKeyPress = False

key_changed = False
key_changed = False

def key_pressed_cb(kc, kp):
    print("key changed: ", kc)
    print" key pressed: ", kp


def tcb(timer):
    global check_msec
    global RawKeyPressed
    global DebouncedKeyPress
    global count
    global key_pressed
    global key_changed
    global button
    
    key_changed = False;
    key_pressed = DebouncedKeyPress
    RawState = button.value()
    if (RawState):
        #set the timer which will allow a c hange from the current state.
        if (DebouncedKeyPress):
            count = release_msec / check_msec
        else:
            count = press_msec / check_msec
    else:
        # key has changed - wait for new state to become stable
        count -= 1
        if (count == 0):
            # timer expired - accept the change.
            DebouncedKeyPress = RawState
            key_changed = True
            key_pressed = DebouncedKeyPress
            key_pressed_cb(key_changed,key_pressed)
            # and reset the timer
            if (DebouncedKeyPress):
                count = release_msec / check_msec
            else:
                count = press_msec / check_msec

                
        
            

    
t1 = machine.Timer(2)
t1.init(period=check_msec, mode=t1.PERIODIC,callback=tcb)

while True:
    print("key pressed: ", key_pressed)