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Is there a good way to pause the script so that add_event_detect() can listen for input? I don't like the idea of using loops so I used raw_input() to pause the script. But does raw_input() really pause the script?

And is this code resource friendly, since I am just listening for events or is there a better/right way to do this?

import RPi.GPIO as GPIO

GPIO.setmode(GPIO.BOARD)

GPIO.setup(11, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(13, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(15, GPIO.IN, pull_up_down=GPIO.PUD_UP)

def my_callback(channel):
    print("Callback on channel: ", channel)

GPIO.add_event_detect(11, GPIO.FALLING, callback=my_callback, bouncetime=300)
GPIO.add_event_detect(13, GPIO.FALLING, callback=my_callback, bouncetime=300)
GPIO.add_event_detect(15, GPIO.FALLING, callback=my_callback, bouncetime=300)

raw_input()
GPIO.cleanup()

1 Answer 1

Reset to default
3

You want signal.pause():

import RPi.GPIO as GPIO
from signal import pause

GPIO.setmode(GPIO.BOARD)

GPIO.setup(11, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(13, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(15, GPIO.IN, pull_up_down=GPIO.PUD_UP)

def my_callback(channel):
    print("Callback on channel: ", channel)

GPIO.add_event_detect(11, GPIO.FALLING, callback=my_callback, bouncetime=300)
GPIO.add_event_detect(13, GPIO.FALLING, callback=my_callback, bouncetime=300)
GPIO.add_event_detect(15, GPIO.FALLING, callback=my_callback, bouncetime=300)

try:
    pause()
except KeyboardInterrupt:
    GPIO.cleanup()

This is what we recommend is gpiozero. Assuming your inputs are buttons, the equivalent would be:

from gpiozero import Button
from signal import pause

btn1 = Button(11)
btn2 = Button(13)
btn3 = Button(15)

def my_callback(btn):
    print("Called by button on pin", btn.pin.number)

btn1.when_pressed = my_callback
btn2.when_pressed = my_callback
btn3.when_pressed = my_callback

pause()

Note that gpiozero provides implicit cleanup at the end of a script; buttons default to pull-up (so falling edge is paired with the button being pressed), and the btn parameter to the callback is optional.

1
  • So signal.pause() is the way to go if you want to minimize the resource usage, is that correct?
    – Mysterious Challenger
    Jan 28, 2021 at 14:56

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