Button working on and off

Question

I have two buttons connected to pins 16 and 20. The one going to pin 20 works well, actually too well. Sometimes when I press it, it records the press two times. The other button which is connected to pin 16 sometimes works and sometimes doesn't. I checked the wiring and connections and that's not it. I have a script that helps me check functionality, and the button is literally just not getting registered every other press or so. Sometimes I can press it 5 times in a row and it will see it, and then I click and click and nothing for 3-4 seconds.

import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BCM)

GPIO.setup(16, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(20, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(21, GPIO.IN, pull_up_down=GPIO.PUD_UP)

def print_msg(x):
    print("Button {} was pushed!".format(x))


while True:
    input_01 = GPIO.input(16)
    input_02 = GPIO.input(20)
    input_03 = GPIO.input(21)

    if input_01 == False:
        print_msg(1)
        time.sleep(0.2)
    
    if input_02 == False:
        print_msg(2)
        time.sleep(0.2)
        
    if input_03 == False:
        print_msg(3)
        time.sleep(0.2)

Answer 1

Ah, the good old days of "It's a hardware problem ... No it's a software problem!" Often correct software logic bumps up against the reality of physical limitations and side effects. What to do ... what to do?

Pullup Resistors

Pullup resistors are to force the switch logic to a known state (True|False) but the reality is that it speeds-the-return to minimize the floating or Maybe state, it does not eliminate it.

Your sleep delays are tied to your detection and print. Nothing wrong with the logic in principle but you are re-reading the switch states very very fast and the state transitions are not instantaneous, there is a Maybe. What's more, reading does affect the output somewhat; hopefully an insignificant amount but repeated high speed pounding might make a difference. As a first step, pull your three sleeps out of the conditionals and put one after the last switch read to slow down your re-reads.

You are invoking the RaspberryPi programmable pullup resistors with pull_up_down=GPIO.PUD_UP. This is an internal pullup resistor of around 50K ohms. As a second step, it might be beneficial to put a physical 20K pullup on the breadboard between the switch and 3.3V power. This will reduce the maybe time a bit and eliminate questions as to the RPi internal pullup logic.

A third step might be to hold a past read (red) state. If the intent is discrete button presses, don't process a new read (reed) if the state is the same as previously read (red). Conversely, don't process a new state unless you read it twice (3?) in a row. If the intent is to handle press duration, require n (2?) new states to acknowledge end.

Good Luck and let us know how you make out!