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Notes

.. currentmodule:: gpiozero

Keep your script running

The following script looks like it should turn an LED on:

from gpiozero import LED

led = LED(17)
led.on()

And it does, if you're using the Python (or IPython or IDLE) shell. However, if you saved this script as a Python file and ran it, it would flash on briefly, then the script would end and it would turn off.

The following file includes an intentional :func:`~signal.pause` to keep the script alive:

from gpiozero import LED
from signal import pause

led = LED(17)
led.on()
pause()

Now the script will stay running, leaving the LED on, until it is terminated manually (e.g. by pressing Ctrl+C). Similarly, when setting up callbacks on button presses or other input devices, the script needs to be running for the events to be detected:

from gpiozero import Button
from signal import pause

def hello():
    print("Hello")

button = Button(2)
button.when_pressed = hello
pause()

Importing from GPIO Zero

In Python, libraries and functions used in a script must be imported by name at the top of the file, with the exception of the functions built into Python by default.

For example, to use the :class:`Button` interface from GPIO Zero, it should be explicitly imported:

from gpiozero import Button

Now :class:`~gpiozero.Button` is available directly in your script:

button = Button(2)

Alternatively, the whole GPIO Zero library can be imported:

import gpiozero

In this case, all references to items within GPIO Zero must be prefixed:

button = gpiozero.Button(2)