squarePi.sh by DokT under MIT License.

Made 20/05/2020, last update 24/05/2020

It's not a true PWM signal, but a square signal. The Raspberry Pi is not capable of that. You might use a capacitor with a resistance to get a sinusoidal signal. WARNING: I'm not responsible for any blown RPIs/IoT devices or electronic components suchs as fans, leds, whatever. Use this tool at your own risk!

trap ctrl-c and call ctrl_c() thanks to this website: https://rimuhosting.com/knowledgebase/linux/misc/trapping-ctrl-c-in-bash dep needed: bc (for math operations) install it with pacman -S bc / apt-get install bc to use this programm.

WHAT'S NEW / CHANGELOG

[beta 0.2]

Small fixes
Logging function implemented but not usable at this moment
Using a variable to touch GPIO but GPIO detection and offset still not implemented (working on!)
Successfully implemented XML files to use it as config.xml (R/W)
Added new dependencies and check

[beta 0.1]

Almost fixed the "preheat" function to allow low frequencies to be set on fans
Fully rewritten code (clearer than it was)
Using "case" instead of "if" as main menu
Detects if the GPIO is unexported (working on)
Add logging function to log files and add color to output (working on)
Using "printf" instead of "echo" to get closer to C langage
Using XML for configs files. (libxml2 is required!)
A better way to check if required dependencies is satisfied and ask user to install them if they aren't installed

[alpha]

first release

Known bugs:

Tell me :)
~~"preheating" doesn't seem to care about the $phs var. So at this moment it does not work.~~ (almost fixed in beta 0.1, considering it as "fixed")

Todo quickly! :

~~Use "case" instead of "if" conditions~~ (patched/added in beta 0.1)
Tell what GPIOs are available for a basic Raspberry Pi (for Pi clones please ask me to add your platform on this software)
Auto detect where the GPIO should be used and export them if they're aren't exported yet and applying offset (issue for ArchLinuxARM users)

ROADMAP:

~~Supporting .conf files to add feataures and allowing the daemon mode~~ (patched/added in beta 0.1)
make it as daemon, so this would add the autostart feature
making a CLI based for setting up when enabling fans and make the daemon using configurations files

Functions that (almost?) works:

XML style as config file (config.xml)
Enable or disable fans
Set custom frequency of the output signal
Make a clean CTRL+C exit
Check if the required ddependencies are satisfied (not a lot of packages are needed, but it prevents from non-working programm on other OSes/systems) (arch user only)

Basic usage :

./squarePi.sh 1 (for enabling) 0.5 (seconds) This will enable fans on the GPIO each 0.5 seconds and will stop it again and again. it will also calculate the frequency (for exemple, 0.3 is 2Hz) To stop it, use CTRL+C.