Raspberry Pi - Fan Control

Simple python daemon to control a fan via GPIO pins and a NPN transistor based on the CPU temperature.

Hardware Setup

• Guide I followed
• What I used:
  • NPN transistor (PN 2222A 6E) with 220 Ohm resistor at the base
  • Raspberry Pi 4B with 8GB RAM
  • 64-Bit Ubuntu Server 20.04 LTS
  • Cooler used: GeeekPi Low-Profile Cooler

Installation

Via docker-compose

• Just run docker-compose up -d

Via systemd unit

• Python version used is 3.8
• Dependencies can be installed with: apt install python3-rpi.gpio
• To setup the daemon I recommend to:
  1. Create a new user: sudo useradd -m fancontrol
  2. Lock the user, so one can not login with it: sudo passwd -l fancontrol
  3. Allow new user to access gpio pins by adding to a group: sudo gpasswd -a fancontrol dialout
  4. Checkout the repository in new users home: cd /home/fancontrol && sudo -u fancontrol git clone https://github.com/danielgolf/rpi-fan-control.git
  5. Copy the systemd unit file: sudo cp /home/fancontrol/rpi-fan-control/rpi_fan_control.service /etc/systemd/system
  6. Reload systemd: sudo systemctl daemon-reload
  7. Activate and run the daemon/service: sudo systemctl enable --now rpi_fan_control.service
• The /home/fancontrol/rpi-fan-control/src/cputemp.py script can be copied or symlinked to $HOME/.local/bin/cputemp

Configuration

In the main script rpi_fan_control.py are four variables for configuration

• GPIO_PIN: Number of GPIO pin to control the fan
• SLEEP_TIME: How long to sleep between each cpu temp check
• CPU_TEMP_FAN_ON: Temperatur on which the fan is turned on
• CPU_TEMP_FAN_OFF: Temperatur on which the fan is turned off

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