25KHz PWM and Pulse Reading, 4 wire DC fan

Projects General Guidance
1

Hello

I'm completely new to Arduino and I'm looking to make a small test box. To be honest I'm not sure if Arduino is the best option but I thought I'd ask.

Basically I have a requirement to test many 12V 4 wire DC Brushless Fan. The fan operates on 25KHz PWM and I want to also read the RPM and display it to a LCD. Additionally I'd like to vary the duty cycle between 0 and 100 with a pot.

I've spent a long time looking at forums and Youtube and I've seen sections of this being done but I'm really not sure if this is something that can all be done together.

So, is it possible to generate a 25KHz PWM signal, with the duty cycle controlled via pot, and the RPM of the fan read back through the Arduino and displayed on a LCD? If so, which Arduino would be best?

The stretch goal for this (as it were) is to test multiple fans at the same time. I don't have an issue powering them all through a PSU as I appreciate it wouldn't be suitable/possible to run all of that through the Arduino.

Thanks very much for any help in advance. As I said, I've not dabbled in Arduino before but I really want to use this as a stepping stone to more Arduino based function test equipment.

Darryl

2

So, is it possible to generate a 25KHz PWM signal, with the duty cycle controlled via pot, and the RPM of the fan read back through the Arduino and displayed on a LCD?

Yes, it is. At 5V, and very little current. Which will do nothing for your fans.

3

25khz is a requirement from Intel, to make fans silent (outside human hearing range).
The fans I tested worked the same on default 1khz PWM (pin 5, 6).

Did you search this site (lollipop on top of this page) for keywords like "4-pin fan RPM".
Leo..

4

Yeah, I've read through a few 4 pin fan RPM threads, the pot part was missing. To be honest, I'd be happy for it to cycle the duty cycle settings on a timer (i.e. 25% for 5 seconds, 50% for 5 seconds, 75% for 5 seconds, 100% for 5 seconds).

I want to test it at 25kHz as the fans will end up in jamming equipment and I want to ensure they're operating as intended.

I think the best bet for me is to perhaps jump in, get coding and see what I can do. I was really hoping for some reassurance that what I'm trying to do it fairly standard.

Is a I2C display the best type to go for? Which Arduino would be best for this?

Thanks