mirror of
https://github.com/KevinMidboe/python-gpiozero.git
synced 2025-10-29 17:50:37 +00:00
44e943b322
Knew I'd missed some patches to the docs! This re-applies the aforementioned doc patches and also fixes the last RGBLED example (which was subtly incorrect in the original docs)
73 lines
1.7 KiB
ReStructuredText
73 lines
1.7 KiB
ReStructuredText
=====
|
|
Notes
|
|
=====
|
|
|
|
.. currentmodule:: gpiozero
|
|
|
|
.. _keep-your-script-running:
|
|
|
|
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)
|
|
|