Rpi3B+ and Audio Amplifier HAT GPIO Pin Push Button False Detection/Triggering Problem

Question

I'm currently having trouble with my project. I'm using a Raspberry Pi 3B+ with an InnoMaker Hifi Amp Hat and some push buttons.

import time
import signal
import os
import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BCM)

debounceTime = 300

btn1 = 24
btn2 = 25
btn3 = 13
btn4 = 12
btn5 = 16

def cb_btn1(channel):
    print('Button 1 pressed')

def cb_btn2(channel):
    print('Button 2 pressed')

def cb_btn3(channel):
    print('Button 3 pressed')

def cb_btn4(channel):
    print('Button 4 pressed')

def cb_btn5(channel):
    print('Button 5 pressed')

class GracefulExit:
    kill_now = False
    def __init__(self):
        signal.signal(signal.SIGINT, self.exit_gracefully)
        signal.signal(signal.SIGTERM, self.exit_gracefully)

    def exit_gracefully(self,signum, frame):
        self.kill_now = True

GPIO.setup(btn1, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(btn2, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(btn3, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(btn4, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(btn5, GPIO.IN, pull_up_down=GPIO.PUD_UP)

GPIO.add_event_detect(btn1, GPIO.FALLING, callback=cb_btn1, bouncetime=debounceTime)
GPIO.add_event_detect(btn2, GPIO.FALLING, callback=cb_btn2, bouncetime=debounceTime)
GPIO.add_event_detect(btn3, GPIO.FALLING, callback=cb_btn3, bouncetime=debounceTime)
GPIO.add_event_detect(btn4, GPIO.FALLING, callback=cb_btn4, bouncetime=debounceTime)
GPIO.add_event_detect(btn5, GPIO.FALLING, callback=cb_btn5, bouncetime=debounceTime)

def main():
    app_killer = GracefulExit()
    while not app_killer.kill_now:
        try:
            time.sleep(0.5)
        except BaseException:
            GPIO.cleanup()
            print "Encountered an axeption."
            break
    print "End of the program."
    GPIO.cleanup()

if __name__ == '__main__':
    main()

I've tried with external pull-up/down and also adding a 0.1uF cap between 3.3V / GND and the GPIO.

I'm not using any pins that the Hat is supposed to use (GPIOs 18 to 21) according to the manual

My setup us currently on a breadboard, maybe I'm getting EMI with the jumpers wires...

I'm using a good quality power supply so I hope the problem isn't coming from here... For reference it's a Mean Well GSM40A12-P1J

I've discovered that touching the metal Ethernet/USB port with the metal tip of an USB flash drive or the tips of my multimeter probe trigger almost all my GPIO each times.

Is there something that I'm missing to get reliable input?

---

Edit: Ok I'm slowly putting the pieces together. In order to make pigpiod running on a non full raspbian image in addition to sudo apt install pigpiodI had to run sudo apt install python3-pigpio

Answer 1

To mitigate against unwanted events I suggest you use code similar to the following. Basically read the level of the GPIO in the callback to verify it is not a short term transient.

#!/usr/bin/env python

import time
import signal
import os
import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BCM)

buttons=[24, 25, 13, 12, 16]

def cb_buttons(channel):
   if GPIO.input(channel) == 0:
      btn = buttons.index(channel) + 1
      print("Button {} pressed".format(btn))

class GracefulExit:
    kill_now = False
    def __init__(self):
        signal.signal(signal.SIGINT, self.exit_gracefully)
        signal.signal(signal.SIGTERM, self.exit_gracefully)

    def exit_gracefully(self,signum, frame):
        self.kill_now = True

for btn in buttons:
   GPIO.setup(btn, GPIO.IN, pull_up_down=GPIO.PUD_UP)
   GPIO.add_event_detect(btn, GPIO.FALLING, callback=cb_buttons)

def main():
    app_killer = GracefulExit()
    while not app_killer.kill_now:
        try:
            time.sleep(0.5)
        except BaseException:
            GPIO.cleanup()
            print "Encountered an axeption."
            break
    print "End of the program."
    GPIO.cleanup()

if __name__ == '__main__':
    main()