Bebump Coolth is a Windows utility that can dynamically control 4 fans connected to an Arduino Nano.

The code and build instructions for the Arduino part are also shared in this repository. That includes a PCB and 3D printable enclosure if you want to make it nice.

Looking at the wiring diagram in the picture up top, you can quickly assemble a working prototype using a breadboard.

You need to program the Nano board with the source file in arduino_nano/fan_controller.ino.

If you want you can set persistent fan speeds stored on the Arduino by sending the following command to it over serial.

c 2 60 60 60 60

Where the last four 0 <= integers <= 255 are the duty cycles for the four fans. During active operation the PC control software can dynamically overrule these values. In case the PC software is not running, or communication fails for more than 3 seconds the Arduino will go back to these persistent values.

You can download a Windows installer from the releases section. You have the option to select automatic launch upon Windows startup from the installer.

After launching Bebump Coolth the program will scan the available COM ports and find the programmed Arduino. It remembers the right COM port, so next time it will open the same port first.

Everyting can be configured from the GUI and using the program should be self-explanatory after a bit of experimentation.

The program must run to keep controlling your fans. If you minimize the application it will become a background process and it will sit on the taskbar notification area consuming next to no resources.

• Visual Studio 2017 (C# and C++)
• CMake 3.15+

You can use these to build every binary artifact. You have to build temperature_reader/temperature_reader.sln and the bebump_coolth target of CMakeLists.txt.

If you want, you can run scripts/build_everything.py which will probably do everything for you from a completely clean checkout. In this case, you also need

• Python 3.6+

Running the script file will ask you to specify the build output directory (or use default). Then it will try to find your Visual Studio installation, and CMake (should be available on your PATH), and then try to build everything.

Worked on my machine.

If you choose the automatic way, there will be a bunch of files in the build output directory.

If you have

• InnoSetup 6.1.2

you can double click and run the coolth.iss file from the build output directory, press the green play button, and you will have your own installer.

If you don't want a fire hazard lying around or inside your computer, you may want to build a proper device with a PCB and 3D printed enclosure.

You can order a PCB by sending the files in arduino_nano/gerber to a PCB manufacturer.

You need to solder the folling components on the PCB.

• 4x Molex 47053-1000 connector
• 1x 5.08 mm PCB terminal block
• 2.54 mm pin headers for connecting the Arduino Nano