raspi-fan-control

Automated PWM fan control for Raspberry Pi. Reads temperature from the CPU thermal zone and drives one or more fans along a configurable curve.

Requirements

• Raspberry Pi running a Debian-based OS (Raspberry Pi OS, Ubuntu, etc.)
• Python 3.11+
• A properly wired up PWM fan:
  • The fan's PWM pin should be wired to GPIO pin 18 (or any other pin that supports PWM)
  • The fan's RPM pin should be wired to GPIO pin 15.
  • The fan's power and ground pins connected to the power supply (technically the Raspberry Pi will power a fan, but it's not ideal and you'll be required to use a 5V fan)
• Root access for installation

Note that the default configuration is set up for a Noctua PWM fan, so by using GPIO pins 18 and 15 this is basically plug and play! However, tweaking the configuration for other fans should be easy.

Installation

1. Create a virtual environment

sudo python3 -m venv /opt/raspi-fan-control

2. Install the package

Install directly from PyPI:

sudo /opt/raspi-fan-control/bin/pip install raspi-fan-control

3. Run the install script

The install script writes the systemd service file, enables it, and starts the service:

sudo /opt/raspi-fan-control/bin/raspi-fan-control-install

The service file is written to /etc/systemd/system/raspi-fan-control.service. Need to update something? No worries, make the change to the template (see Configuration below), then re-run the install script to apply changes.

Configuration

All configuration is supplied as Environment= entries in the systemd service file at /etc/systemd/system/raspi-fan-control.service. The prefix RFC__ maps to the top-level config, and double underscores (__) delimit nesting.

After editing the service file, apply changes with:

sudo /opt/raspi-fan-control/bin/raspi-fan-control-install

Top-level

Fan (RFC__FANS__<index>__...)

PWM (RFC__FANS__<index>__PWM__...)

RPM (RFC__FANS__<index>__RPM__...)

Fan curve (RFC__FANS__<index>__CURVE__POINTS__<index>__...)

The curve maps a normalized temperature (0.0-1.0) to a normalized duty cycle (0.0-1.0). Add as many points as needed; they are interpolated linearly. By default it will use a simple linear fan curve from (0.0, 0.0) to (1.0, 1.0).

Temperature sensor (RFC__TEMPERATURE_SENSORS__<index>__...)

Note that the ...__TEMPERATURE_MIN_C and ...__TEMPERATURE_MAX_C values define the upper and lower bounds that the fan curve will use when determining how fast to spin the fans. Currently the values are sensible defaults for the Raspberry Pi, but you may wish to tweak them for more complex (or non Raspberry Pi based) scenarios.

Example service file

Check out the systemd service file.

Managing the service

It's a systemd service so it can be managed via systemctl like any other, but here's a couple handy commands:

# Restart after config changes
sudo /opt/raspi-fan-control/bin/raspi-fan-control-install

# View logs (follow them)
sudo journalctl -u raspi-fan-control -f