How To Add A Button To Trigger Script For Rasberry Pi

Pulling the power to your Raspberry Pi can cause image corruptions & other issues that can damage your Pi! In this article, we will create a small button that will piece of work as a 'Rubber-Shutdown' option. We'll connect it to our Raspberry Pi using the GPIO pins and some jumper wires, and with a few lines of code, we will have our own power switch!

First, nosotros are going to look at a simple way to wire a button to the Pi GPIO connector. We will then write a python script that will shut down the Pi safely. The final step volition be to setup the Pi and then that the push button will piece of work all the time. Allow's Get started!

What you volition need:

Raspberry Pi B+ (Any Pi volition piece of work Simply make certain y'all check the GPIO pins)
Tactile Switches
Female/Male Extension Jumper Wire Packs
Solderless Breadboards

The Excursion

To do this we will wire the button to GPIO Pin 26(Yellow wire) and to ground (Green wire). This configuration is called an Active Depression button, this means that when the button is pushed it volition accept no voltage or be logic low. The Pi has pull-up resistors on its GPIO pins so wiring active low mean we do not need to add an external resistor.

Brand sure you are extremely careful with the wiring here equally shorting the wrong pins together tin can kill your Pi. Which is why I at present have a Pi-shaped coaster.

safe-shutdown-pi-circuit-diagram

The Script

from gpiozero import Button #import button from the Pi GPIO library import time # import time functions import os #imports Os library for Shutdown command  stopButton = Button(26) # defines the push button as an object and chooses GPIO 26  while Truthful: #space loop      if stopButton.is_pressed: #Check to see if button is pressed         time.sleep(1) # expect for the concord time we want.          if stopButton.is_pressed: #check if the user let get of the button             bone.system("shutdown at present -h") #close down the Pi -h is or -r volition reset     time.sleep(i) # wait to loop again so we don't use the processor as well much.

We are going to use three external libraries:

The button module from the gpiozero library, this library gives easy access to programming the GPIO on the Pi.
The time library, and so we can wait in homo time.
The bone library gives us the power to shut down the Pi (You lot tin can also employ this library to run any terminal commands!).

We first create a button object that lets us collaborate with the button. We will give this function the input of GPIO number nosotros fastened the push button to 26 in our case. By default, this function assumes agile low buttons so nosotros do not demand to change anything else.

We desire this programme to exist running all the time so that when we press the button after a week-long retro gaming session it will even so work. To do this we create while True loop that volition keep running forever.

Inside the loop, we take 2 if statements the first will observe a push button printing so trigger the code to wait for a second then check and see if the button is even so held downward.

The last line tells the loop to wait ane second earlier checking the push again, we are not in a hurry, so we can wait for presses. Make sure yous include this await without it python will run this script as fast as it can and that will put unnecessary load on the CPU.

You can now run this program and test information technology considering we are using the os command nosotros demand to run this script as sudo too.

sudo python /home/pi/piShutdown.py

though brand sure yous save all your work first!

Making It Piece of work

And then that our push button will work nosotros need to tell the Pi to run the script on kickoff-upwards. To practice this we alter the rc.local file, In essence, rc.local is a to-do listing the Pi follows as information technology starts up. In guild to add more items to this listing, we demand to edit information technology. rc.local is protected by the operating arrangement so we need to open, or do, it as a Super User (sudo). I am going to utilise leafpad to edit rc.local because I am not hacker enough to employ nano.

sudo leafpad /etc/rc.local

Into rc.local nosotros are going to add a command to run our shutdown script we will add this on the line earlier exit 0 as shown.

sudo python /dwelling/pi/piShutdown.py &
get out 0

It is very of import to remember the '&' at the end this tells the Pi to run this program in the groundwork. If you do not do this it will wait for the infinite loop to finish before moving to the side by side particular on its to-exercise list. Save the file and exit if you lot are using leafpad yous can use the menus. This concluding footstep can also be washed with crontab a congenital-in scheduler for the Pi(and all Linux distributions! ).

All done! Reboot your Pi and you should have a Safe Shutdown push button that works! If something didn't work quite equally y'all expected or you want to investigate using alternate logic for your switch, become in touch with u.s. and inquire the questions. We're here to assistance!