Interrupt button debounce with long / short press

crankshaft

@mohpor - Thanks for helping, but I get multiple short presses (1 to 6) even if I increase the t > 100.

Am also getting a crash:

Short 0
Short 0
Guru Meditation Error of type LoadProhibited occurred on core  0. Exception was unhandled.
Register dump:
PC      : 0x40081b87  PS      : 0x00060330  A0      : 0x800de62b  A1      : 0x3ffe15f0
A2      : 0x65642728  A3      : 0x3ffc39d8  A4      : 0x3ffe1a40  A5      : 0xd58eb6e0
A6      : 0x3ffe16f8  A7      : 0x0000005b  A8      : 0x80083f91  A9      : 0x3ffe15b0
A10     : 0x00000003  A11     : 0x00060723  A12     : 0x00060723  A13     : 0xb33f0000
A14     : 0xb33fffff  A15     : 0x3ffe16c0  SAR     : 0x00000002  EXCCAUSE: 0x0000001c
EXCVADDR: 0xd58eb6e0  LBEG    : 0x400014fd  LEND    : 0x4000150d  LCOUNT  : 0xffffffff

Backtrace: 0x40081b87:0x3ffe15f0 0x400de62b:0x3ffe1610 0x400ecec0:0x3ffe1630 0x400e95a8:0x3ffe1650 0x400e9615:0x3ffe1670 0x400e2905:0x3ffe1690 0x400e047c:0x3ffe16d0 0x400f325a:0x3ffe16f0 0x400ecea1:0x3ffe1710 0x400e95a8:0x3ffe1730 0x400e9615:0x3ffe1750 0x400f4b68:0x3ffe1770 0x400ecfcd:0x3ffe1810 0x400e95a8:0x3ffe1850 0x400e95ec:0x3ffe1870 0x400dbf50:0x3ffe18a0 0x400e071f:0x3ffe18c0 0x400d7e80:0x3ffe1940

                                                                                                                              Rebooting...
ets Jun  8 2016 00:22:57

rst:0x3 (SW_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0x00

I added a print(t) after t = chrono.read_ms() so I could monitor the time, and pressed the button quickly and got 3 hits all with the same timestamp:

>>> execfile('dev.py')
Ram Free: 84.40%
waiting...
0.0
182.9711
Short 0
182.9711
Short 0
182.9711
Short 0

mohpor

@crankshaft That's strange, I have been using this code for more than 2 weeks now, without a single double press or any crashes! What are using as button? A micro switch?

crankshaft

@mohpor - it's one of those common, small through-hole tactile buttons, but anyway I have your code working now with what appears to be 100% reliability and no double presses:

I added a check for last value and ignored it if received:

last = 0
def btn_press_detected(btn):
  global chrono, timer, last
  try:
    val = btn.value()
    if 0 == val:
      chrono.reset()
      chrono.start()
      timer.callback(long_press_handler)
    else:
      timer.callback(None)
      chrono.stop()
      t = chrono.read_ms()
      if(t==last): return
      last = t
      if (t > 30) & (t < 200):
        single_press_handler()
  finally:
    gc.collect()

Thanks so much for your help, although it does seem incredibly long-winded to achieve this when the same thing can be done on the RPI pins with a built in debounce option !

mohpor

@crankshaft
Happy to help and glad it's over.

100% agreed on the comment, if the button is debounced, that's two less interrupt handlers required and at least some bytes freed from memory.

Cheers,
M.

livius

@crankshaft
good to see that you finally solve it
but i have question - because i saw this behavior self when i have too big/too small pullup/pulldown.
Do you use internal pin pullup or pull down. Or do you use external resistor? If external - what value?

EDIT
+1 for debounce option
add it to:
https://forum.pycom.io/topic/433/features-wish-list

crankshaft

I came up with another version that also works:

def long(count):
   print('Long Press',count)  

def short(count):
   print('Short Press',count) 

count = 0
butms = 0
def btn_press_detected(pin):
  global butms, count
  now = time.ticks_ms()
  if butms == 0: butms = now 
  else:
    if butms == now: return
  i = 0
  while i < 10:
    time.sleep_ms(1)
    if pin() == 1: i = 0
    else: i+=1
  while pin() == 0:
    i+=1
    if(i > 1000): break
    time.sleep_ms(1)
  
  count +=1   ## debug check for double-trigger only
  if(i>1000): long(count)
  else: short(count)

crankshaft

In case anyone is interested I created a class:

from time import sleep_ms, ticks_ms
from machine import Pin
import gc

class BUTTON:

  def __init__(self,pid='P12',longms=1000):
    self.longms = longms
    self.butms = 0
    self.pin = Pin(pid, mode=Pin.IN, pull=Pin.PULL_UP)
    self.pin.callback(Pin.IRQ_FALLING | Pin.IRQ_RISING,  self.press)

  def long(self):
    pass

  def short(self):
    pass
  
  def press(self,pin):
    now = ticks_ms()
    if self.butms == 0: self.butms = now 
    else:
      if self.butms == now: return
    i = 0
    while i < 10:
      sleep_ms(1)
      if self.pin() == 1: i = 0
      else: i+=1
    
    while self.pin() == 0:
      i+=1
      if(i > self.longms): break
      sleep_ms(1)
    
    if(i>1000): self.long()
    else: self.short()
    while self.pin() == 0: pass
    gc.collect()

And to call it:

def short():
  print('short')

def long():
  print('long')

import button
but = button.BUTTON()
but.short = short
but.long = long

crankshaft

@livius - I am using internal pullup, I could also add a decoupling capacitor across the switch but I wanted to do it all in software instead.

gael-wogenstahl

@crankshaft
Hello !
I've tried to use your class with 3 different buttons but it seems once a button interrupt is triggered, all other buttons interrupts don't work anymore and only the future interrupts from the first pressed button are triggered.
I've been searching a lot for an explanation but couldn't find any.
Did you experience that kind of behavior ? Do you have a clue as to where that can come from ?
Thanks for your help !

livius

@gael-wogenstahl
can you show how you declare all?
Code for three buttons?

gael-wogenstahl

@livius
here are the BUTTON class code (slightly modified from your version, mainly to add comments)

from time import sleep_ms, ticks_ms, ticks_diff
from machine import Pin
from _thread import start_new_thread
import gc

class BUTTON:

  def __init__(self, pid='P10', longms=1000):
    self.pressms = 0
    self.longms = longms
    self.pin = Pin(pid, mode=Pin.IN, pull=Pin.PULL_UP)
    self.pin.callback(Pin.IRQ_FALLING | Pin.IRQ_RISING, self.press)

  def long(self):
    pass

  def short(self):
    pass

  def press(self, pin):
    # If never pressed, store press time
    if self.pressms == 0: self.pressms = ticks_ms()
    else:
      # If pressed within 500 ms of first press, discard (button bounce)
      if ticks_diff(self.pressms, ticks_ms()) < 500: return

    # Wait for value to stabilize for 10 ms
    i = 0
    while i < 10:
      sleep_ms(1)
      if self.pin() == 1: i = 0
      else: i+=1

    # Measure button press duration
    while self.pin() == 0:
      i+=1
      if(i > self.longms): break
      sleep_ms(1)

    # Trigger short or long press
    if(i > self.longms):
      start_new_thread(self.long, ())
    else:
      start_new_thread(self.short, ())

    # Wait for button release
    while self.pin() == 0: pass
    self.pressms = 0
    gc.collect()

and here is the code I use to instantiate the different buttons

import button

def short_red():
  print('Short red button press')

def long_red():
  print('Long red button press')

def short_yellow():
  print('Short yellow button press')

def long_yellow():
  print('Long yellow button press')

def short_black():
  print('Short black button press')

def long_black():
  print('Long black button press')

red_button = button.BUTTON(pid='P22',longms=500)
red_button.short = short_red
red_button.long = long_red

yellow_button = button.BUTTON(pid='P21',longms=500)
yellow_button.short = short_yellow
yellow_button.long = long_yellow

black_button = button.BUTTON(pid='P10',longms=500)
black_button.short = short_black
black_button.long = long_black

mahe

@gael-wogenstahl

Hi,

I'm experiencing the same kind of problems - did you ever solve it?

Thanks

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Interrupt button debounce with long / short press

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