/raspberrypi-fan-control

Raspberry Pi Adjust Fan Speed With Temperature [C - WiringPi - Pigpio - Noctua PWM Fan]

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Raspberry Pi Fan Control

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Preview

RP4-github

Intro

Raspberry Pi fan-control service to adjust PWM fan speed automatically based on CPU temperature. It will help in reducing fan noise and power consumption. It is written in C. Main objective is to keep it fast and use minimum CPU and memory resources.

resource-usage

If you just want PWM fan On/Off based on CPU temperature. Connect fan's PWM, ground and +5V wires directly to the GPIO pins. Enable fan either from raspi-config or UI. Set the PWM pin and CPU temperature in the setup. Lowest temperature limit of 60°C can be bypassed by editing /boot/firmware/config.txt manually. Find dtoverlay=gpio-fan entry and change the temp=60000 to the desired temperature. Fan will start at the specified CPU temperature and it will stop 10°C below that. The downside is fan will run at full speed and bit noisy, specially if you are using an open RP4 case.

This service is specifically written for Noctua 5V PWM fan and Raspberry Pi 4. It may work for other PWM fans and RP models. You should know the intended fan's specifications, like max / min RPM and target frequency. Adjust these values in code/config and rebuild the binary (if needed).

I connected Noctua fan wires directly to the RP4 GPIO pins. It's been almost 3 years without any issue, your mileage may vary. If your fan does not support PWM or you want to safeguard hardware either build your own circuit or buy a pre-built PCB with transistor and diode like EZ RP Fan Controller.

⚠️ WARNING: I accept no responsibility if you damage your Raspberry Pi or fan.

Specs:

Noctua Fan HW OS WiringPi pigpio
NF-A4x10 5V PWM Fan Raspberry Pi 4 Model B raspios-bookworm-arm64-lite 3.1 79

Hardware Prep

  • The default noctua fan connector will not connect directly to GPIO header. You need to do some modifications. There are multiple options:

    1 - Dupont Jumper Wires Male to Female:
    Noctua's existing wire is pretty long. Get short jumper wires somewhere between 2-4" long. Male part of jumper wire will connect to Noctua connector and Female part will connect to GPIO. I used it for few months.

    2 - Dupont Female Pin Connectors 2.54mm Pitch:
    It is the cleanest option, as shown in the preview. You need dupont Female pin connectors, crimping tool, wire cutter & stripper, heat-shrink-tube & heat-gun or dupont connector housing.
    Better options for dupont connectors are Molex Crimp Terminals Series: 70058 Part No: 16020098 or Harwin Series: M20 Part No: 1180042. I used Molex connectors and IWISS IWS-2820 crimping tool. Cover these connectors with either heat shrink tube (3.00mm diameter tube) or dupont connector housing.

    3 - Use Wires from Old Fan:
    If you have some old unused fan laying around that has dupont connector wires. Cut the wires from that fan, cut the Noctua connector and do some wire joining. Noctua fan's OmniJoin adaptors can be used for joining wires.

  • Complete specification of Noctua fan is available at Noctua Whitepaper. Details of Raspberry Pi GPIO pin layout is available at GPIO Pinout. Screenshots attached for quick reference.

    Fan Wires GPIO Layout
    noctua_pin_config gpio_layout

  • Fan wires connection to RP4 pins:

    Fan Wires RP4 Pins
    Yellow +5V Physical Pin 4
    Black Ground Physical Pin 6
    Blue PWM Signal Physical Pin 12
    Green RPM Signal Physical Pin 16

    Fan's PWM signal wire is connected to the RP4 Physical pin 12 - GPIO pin 18. This fan-control code uses GPIO 18 as default. There are 4 pins on RP4 that support hardware PWM GPIO 12/13/18/19. If you are going to use a different GPIO pin make sure you change the PWM_PIN in params.conf with the one you use.
    The green tachometer wire on Noctua fan is used to calculate RPM. Connect the fan's RPM signal wire to the RP4 Physical pin 16 - GPIO pin 23. By default, tacho output is disabled in params.conf. (refer to Points to Note)

Steps

❯ Install C Library

  • Install either WiringPi or pigpio C library.

    • WiringPi
      Download and install WiringPi C library.

      Install:
      sudo dpkg -i wiringpi_3.1_arm64.deb

      ℹ️ Note:
      WiringPi has been revived. Latest release supports RasberryPi OS Bookworm. Check the github repo for updates.

    • Pigpio
      Download and install pigpio C library.

      Install:
      unzip -o pigpio-master.zip
      make
      sudo make install

      ℹ️ Note:
      Uninstall Pigpio:
      If pigpio was installed using the previous step, manually remove all files under /usr/local/* mentioned here. To remove the distro provided pigpio package run cmd sudo apt --purge autoremove pigpio

❯ Install FanControl

  • Download the latest fan-control release for the library that was installed in the previous step. Create folder /opt/gpio/fan. Copy fan-control and params.conf from the latest release under build folder to this newly created folder /opt/gpio/fan. Make sure both files are under the ownership of root and fan-control is executable. Fan-control will work with default values without params.conf.

    Create folder:
    sudo mkdir -p /opt/gpio/fan/

    Make binary executable [If needed]:
    sudo chmod +x /opt/gpio/fan/fan-control

    Change ownership [If needed]:
    sudo chown root:root /opt/gpio/fan/fan-control
    sudo chown root:root /opt/gpio/fan/params.conf

  • Create service to automatically run the fan-control at startup. Copy fan-control.service from the latest release under service folder to /etc/systemd/system/. Make sure file is under the ownership of root. Enable the service.

    Change ownership [If needed]:
    sudo chown root:root /etc/systemd/system/fan-control.service

    Enable Service:
    sudo systemctl enable fan-control

    Start Service [If needed]:
    System reboot will automatically start the service. To start without reboot.
    sudo systemctl start fan-control

    Check Service Status:
    sudo systemctl status fan-control

    Check Journal Logs:
    sudo journalctl -u fan-control

Points to Note

  • Noctua's green RPM signal wire (aka tacho) connectivity is optional. It generates tacho output signal. It does not add any value in controlling fan speed. That is why it is disabled by default in params.conf. To retrieve RPM periodically through tacho output signal in the logs, connect the wire as mentioned under Hardware Prep and enable it in params.conf. Change TACHO_ENABLED to 1.

  • Fan runs at full speed when RP4 is booted. When fan-control service starts during boot process fan will either switch off or adjust its speed, depending on CPU temperature. Fan-control service runs the fan within the temperature range from 40–55°C and above. Temperature range is configurable through params.conf. Noctua fan's recommeded minimum RPM is 1000. I kept the minimum RPM at 1500 in this service. Table below explains the fan's operation:

    Temp RPM
    <= 40°C 0
    > 40°C 1500
    Temp++ RPM++
    >= 55°C 5000

  • params.conf can be used to configure values of adjustable parameters. Fan-control service will work with default values without params.conf. Restart fan-control service after any change in params.conf. Table below gives an overview of all adjustable parameters.
    * Do not change values if you do not know what you are doing

    Parameters Default Info
    PWM_PIN 18 HW PWM GPIO pins on RPi4B: 12, 13, 18, 19
    TACHO_PIN 23 Tacho pin, enable through TACHO_ENABLED
    RPM_MAX 5000 Fan's max speed. Noctua Specs: Max=5000
    RPM_MIN 1500 Fan's min speed. Noctua Specs: Min=1000
    RPM_OFF 0 Fan off
    TEMP_MAX 55 Max temperature in °C to run fan at max RPM
    TEMP_LOW 40 Min temperature in °C to start fan at min RPM
    WAIT 5000 Wait interval between adjusting RPM
    TACHO_ENABLED 0 Enable tacho, 0=Disable 1=Enable
    THERMAL_FILE /sys/class/thermal/thermal_zone0/temp Path to RP4 thermal file

  • The 5V pins on RP4 i.e., physical pin 2 and 4 are not GPIO. They are connected to the 5V power supply and are always on. Those cannot be turned off without some form of circuit using mosfet or transistor. The point is if you run shutdown command from a shell or UI the fan will keep on running at full speed unless you unplug the RP4.

  • Fan-control logs to the journal at startup and exit. It also logs periodically when fan is on. You can change log level to MaxLevelStore=info in journald.conf to reduce logging.

Build

  • Install libsystemd-dev. It is required for compiling fan-control source code.

    sudo apt install libsystemd-dev

  • Binary is available in the release. If for any reason you want to recompile.

    WiringPi:
    sudo gcc -Wall -O2 fan-control-wiringpi.c -o fan-control -lwiringPi -lsystemd
    Pigpio:
    sudo gcc -Wall -O2 fan-control-pigpio.c -o fan-control -lpigpio -lsystemd