PWM Raspberry Pi Fan Controller

🛑 DEPRECATED! - This utility is deprecated and has been superseded by a much improved fan controller - "Raspberry Pi PWM Fan Control in C and Python"

This library uses a stepwise function to control the fan speed which results in fans cycling on/off more than they need to. It's highly recommended you uninstall this controller script and upgrade.

Uninstall Instructions:

# From the project's root with the makefile
# - Removes systemd service
# - Removes binary
# - Stops service
sudo make uninstall

✅ V2 Install Instructions »

Historical readme.md:

Lightweight low-complexity fan controller that uses CPU temp that resides at /usr/sbin/pwm_fan_control.

Also comes with easy to use systemd service.

Wiring:

This configuration is for a 5V PWM fan!

Pin numbers are basic Raspberry Pi "pin 1 starts at J8" numbers (not GPIO/etc. numbers).

PWM +5V - Pin 4
PWM Ground - Pin 6
PWM Speed Set - Pin 12
PWM Speed Read - (not required/supported) Pin 18; bridged to pin 17 (3.3V) with a 1k Ohm resistor

Wiring Notes:

For a better visual follow wiring diagram listed here: https://blog.driftking.tw/en/2019/11/Using-Raspberry-Pi-to-Control-a-PWM-Fan-and-Monitor-its-Speed/#Wiring
The PWM speed read is optional and can be wired if you want to read the actual fan speed as seen in the previous link

Building/Installing:

Requirements:

wiringPi.h obtainable from https://github.com/WiringPi/WiringPi (build script is in root of WiringPi project)

# Compile
make compile

# Compile with debugging enabled
make compile-debug

# Running (requires sudo to control GPIO)
sudo ./pwm_fan_control

# Installing (will make persistent service that starts at boot)
sudo make install
sudo make uninstall

Use:

# Run with default PWM GPIO #12
pwm_fan_control

# Display help:
pwm_fan_control --help

# Raspberry Pi CPU PWM Fan Controller 
#
# Usage: pwm_fan_control [OPTION]... 
#
# Watches CPU temp and sets PWM fan speed accordingly with WiringPi library.
#
# --gpio BCM_GPIO_PIN_NUMBER       (default 18) BCM GPIO pin # for setting PWM fan speed 
#                                               12, 13, 18, 19 pins supported (hardware PWM) 
#
# Exit status: 1 if error 

##############

# Set a different PWM speed set GPIO pin
pwm_fan_control --gpio 13

systemd Service GPIO Override - If you're using this with a GPIO different than 18 you will want to update the systemd service to add the --gpio argument as-seen below:

sudo nano /etc/systemd/system/
# Replace "ExecStart=/usr/sbin/pwm_fan_control"
#    with "ExecStart=/usr/sbin/pwm_fan_control --gpio 13"

pigpio Instead of WiringPi

I did try to port this over to the better-supported pigpio library as-seen on the pigpio_refactor branch.

Unfortunately it resulted in consistent 5-10% CPU use on a Raspberry Pi 4 which was unacceptable for a simple use. The above branch is working but should be considered unsupported for the time being.

folkhack/raspberry-pi-pwm-fan