如何等到你在python中释放按钮

Question

Is it possible to have a python script pause when you hold a button down and then start when you release that button? (I have the button connected to GPIO pins on my Raspberry Pi)

Answer 1

I am assuming that the button you are using is in GPIO18, so you can use this code.

import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BCM)

GPIO.setup(18, GPIO.IN, pull_up_down=GPIO.PUD_UP)

while True:
    input_state = GPIO.input(18)
    while not input_state:
        # as soon as your button is pressed you
        # will be inside this loop
        print('Button is being pressed')

Alternatively you can also try:

import time
import RPi.GPIO as GPIO

PIN = 18

GPIO.setmode(GPIO.BCM)
GPIO.setup(PIN, GPIO.IN, pull_up_down=GPIO.PUD_UP)

while True:
    GPIO.wait_for_edge(PIN, GPIO.FALLING)
    print "Pressed"
    # your code

I think the second targets more precisely your request.

Answer 2

Have you looked at gpiozero ? It makes interacting with GPIO much simpler.

from gpiozero import Button

button = Button(2)

button.wait_for_press()    
button.wait_for_release()
print("Button was pressed and released")

Here's the link to the Button class: https://gpiozero.readthedocs.io/en/v1.3.1/api_input.html#gpiozero.Button.wait_for_release

And examples of how to use it: https://gpiozero.readthedocs.io/en/v1.3.1/recipes.html#button