README.md

arduino-nano-fancontrol

A simple PWM fan control based on an Ardiuno nano.

I use this to cool a the compartment some hardware is running in since ventilation in this compartment is very bad. The fan shall be turned on depending on the temperature.

Hardware used

• Arduino Nano
• A fan than can be controlled via PWM.
  • I used a Noctua NF-F12 5V PWM. I use the included adapter to power the fan and the Arduino Nano.
  • DO NOT power the fan via the Arduino 5V pin. It will most likely drain way too much energy and kill the Arduino!
• Bread board, some cables and a LED.
• A DS18B20 temperature sensor. You can use other sensors as well, but then you have to change parts of the code.

The temperature sensor is connected to digital pin 2 (ONE_WIRE_BUS). Don't forget to add a resistor. The led is connected to digital pin 6 (LED). The PWM signal is generate on digital pin 3 (pwmPin) and the rpm signal of the fan is read on digital pin 4 (rpmPin).

The cabling has been done as in tutorials online. For that, please see the section "Acknowledgements".

Software

The Arduino sketch can be found in src/. The code is a bit messy at the moment, but should have sufficient comments.

The fan will be turned as soon as a certain temperature (temp_start) is reached. It will be turned off again as soon as the fan has run a certain time period (MIN_TIME_RUNNING) and the temperature is below a threshold (temp_stop). This should keep the fan from turning on and off all the time. While the fan is running a led is turned on.

Bugs

• After turning the device on the fan spins up for MIN_TIME_RUNNING seconds. That was not intended. Maybe I need to add some delay after boot up so everything is initialized properly and that the temperature sensor gives sensible temperature readings.

Dependencies

Arduino Libraries:

• OneWire
• DallasTemperature

Acknowledgements

This codes is based on codes from the following homepages (last checked: 2019-10-13):

• Computation of fan RPM: https://www.hackster.io/Buechner/4-wired-fan-control-pwm-bb29ac
• Running 1-wire bus and reading temperature of DS18B20 temperature sensor: https://create.arduino.cc/projecthub/TheGadgetBoy/ds18b20-digital-temperature-sensor-and-arduino-9cc806
• Running PWM at 25 kHz: https://forum.arduino.cc/index.php?topic=415167.0 (post by dlloyd)

Further homepages that gave valuable input and inspiration:

• PWM fan control: https://www.instructables.com/id/Temperature-Control-With-Arduino-and-PWM-Fans/