KevinMidboe/python-gpiozero
1
0
Fork 0
mirror of https://github.com/KevinMidboe/python-gpiozero.git synced 2025-10-29 17:50:37 +00:00
Code Issues Packages Projects Releases Wiki Activity

Tidy up faqs page

Browse Source
This commit is contained in:
Ben Nuttall
2017-07-26 18:20:51 +01:00
parent d5f6290b0a
commit 443c601a32
1 changed files with 49 additions and 48 deletions
Download Patch File Download Diff File Expand all files Collapse all files

97
docs/faq.rst
View File

@@ -7,6 +7,50 @@ Frequently Asked Questions
.. currentmodule:: gpiozero
.. _keep-your-script-running:
How do I keep my 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()
My event handler isn't being called?
====================================
@@ -96,65 +140,22 @@ version of gpiozero is available in your Python environment like so:
>>> from pkg_resources import require
>>> require('gpiozero')
[gpiozero 1.3.2 (/usr/lib/python3/dist-packages)]
[gpiozero 1.4.0 (/usr/lib/python3/dist-packages)]
>>> require('gpiozero')[0].version
'1.3.2'
'1.4.0'
If you have multiple versions installed (e.g. from ``pip`` and ``apt``) they
will not show up in the list returned by the ``require`` method. However, the
first entry in the list will be the version that ``import gpiozero`` will
import.
If you receive the error "No module named pkg_resources", you need to install
the ``pip`` utility. This can be done with the following command in Raspbian:
If you receive the error ``No module named pkg_resources``, you need to install
``pip``. This can be done with the following command in Raspbian:
.. code-block:: console
$ sudo apt install python-pip
$ sudo apt install python3-pip
Alternatively, install pip with `get-pip`_.
.. _get-pip: https://pip.pypa.io/en/stable/installing/
.. _keep-your-script-running:
How do I keep my 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()