RPi-Fan-Driver

A simple PWM-based driver for your Raspberry Pi Fan

What is this?

This is a DIY project for adding a driver for your Raspberry Pi fan. Using its GPIO pins, some cheap components, a bit of Python code and a custom PCB, the fan can be used at various speeds depending on temperature instead of having 2 different speeds changing between 3.3 and 5V pins. In addition, it is beginner-friendly enough so that anyone can make this easily in a short amount of time.

What do I need for making this myself?

Just a little bunch of things:

• A PN2222A (or similar transistor)
• A common diode that supports at least 5V and around 300-500 mA
• 1K resistor
• A bunch of jumper wires (or solder any wire to the RPi and/or PCB)
• Soldering iron
• The PCB in this repo (I ordered it at JLCPCB)

Instructions

• First of all, I recommend trying this build on a breadboard (see this link for extra information about building this on a breadboard)
• Once inserted all components properly on breadboard download the code from this repo with git clone https://github.com/Pelochus/RPi-Fan-Driver.git or download directly from Releases tab in github.com
• Edit both minspeed-calibration.py and rpi-fan-driver.py with your preferred GPIO pin (Note: BCM numbering is used)
• Optional: Run minspeed-calibration.py and insert values until you find your minimum speed for your fan (should be around 20-40%, default is 50%). Note: Needs rpi.gpio library already installed
• Optional: change tempSteps and speedSteps in rpi-fan-driver.py
• Now run install.sh as root sudo ./install.sh. This will only work with distros that use apt (Debian-based) and have bash (pretty much every distro). If you don't have apt you can manually install rpi.gpio Python library manually
• Reboot
• Make sure is working properly. Try to run any heavy task on the CPU, like a benchmark. The fan should start spinning at a certain temperature (default 45ºC) and keep increasing linearlly according to temperature changes
• Now, if everything works properly, order your PCB
• Solder all the components to the PCB (diode, transistor and resistor)
• Finally connect the wires to their corresponding pins in your RPi and holes in PCB. Even though I soldered the wires to the RPi, I suggest using as much as possible jumper wires
• Put the PCB in a safe place without making contact to the RPi board (Warning: If your PCB makes any contact with your RPi motherboard, something bad will happen, probably you will end up with a fried PCB and/or RPi)
• Optional: Print the .stl in this repo to protect lower part of the PCB (useful for previous step)
• Put the build inside your RPi case similarly to my build (see images below)
• Done!

Pictures

Below some pictures of my build. Tested on Rasbperry Pi 3B

Circuit Schematics

PCB in EasyEDA

Credits

This Instructables article for providing me the electronics diagram and code to make this