Noctua 4-pin PWM fan speed control

[hcet14]

@reneas

I don’t have a lot of experience working with electronics but I am aware of the basics

@mykepredko

When you said you knew some basic rules in electronics, I suggest that you add “Have a common Ground to all the circuits.”

I like that. Reminds of “Good Evening Mr. Waldheim” from Lou Reed. People and electronics are very similar

…but back to the topic.
@reneas, @EddyMI3D, and @mykepredko you all can do better

I took the nomenclature from EddyMI3D in the second post.

My proposal was, that reneas might copying this

to his setup. Fan, dc converter and SKR Mini E3 v3.0 and come out with something like this

All the latest schematics are nonsense in my eyes!

In my connection proposal are the used heathers close together, it should be easy to connect with a multicore cable. Don’t know your physical setup!

I never tried that setup, therefore @reneas, before you connect the “Tacho” signal behind the diode to your SKR Mini E3 v3.0! Measure the signal with a multimeter. If you measure anything above 3,3V stop immediately and tell us here!

Please correct me, if I made a mistake!

[reneas]

@hcet14

… and come out with something like this

All the latest schematics are nonsense in my eyes!

Okay will try this!

@hcet14

In my connection proposal are the used heathers close together, it should be easy to connect with a multicore cable. Don’t know your physical setup!

I don’t quite understand what you mean by that to be honest.

@hcet14

I never tried that setup, therefore @reneas, before you connect the “Tacho” signal behind the diode to your SKR Mini E3 v3.0! Measure the signal with a multimeter. If you measure anything above 3,3V stop immediately and tell us here!

So i should measure the voltage between the green wire and GND? And you probably mean to measure it with the fan turned on, yes?
So first of all i will try this without connecting the tach signal and just the VCC, GND and PWM cables connected.

My printer.cfg should look something like this then:

[fan]
pin: !PD2              # do I need the "!" for inverting the signal?
cycle_time:  0.00004   # This is for 25kHz -> 1/25000 = 0.00004
hardware_pwm: False    # or True because of really low cycle_time?
off_below: 0.2
tachometer_pin: PD0
#enable_pin:           # Do I need this?
#   Optional pin to enable power to the fan. This can be useful for fans
#   with dedicated PWM inputs. Some of these fans stay on even at 0% PWM
#   input. In such a case, the PWM pin can be used normally, and e.g. a
#   ground-switched FET(standard fan pin) can be used to control power to
#   the fan.

Can you help me out with the correct configuration?

Edit: I did not put the values in from which I thought that the defaults as specified here are sufficient for this setup.

[hcet14]

@reneas

@hcet14

In my connection proposal are the used heathers close together, it should be easy to connect with a multicore cable. Don’t know your physical setup!

I don’t quite understand what you mean by that to be honest.

Heathers are the connectors to the IO pins, Voltages, and Ground. The heathers I coose for my proposal are close together, thats all. Easy to wire.

@reneas

So i should measure the voltage between the green wire and GND? And you probably mean to measure it with the fan turned on, yes?
So first of all i will try this without connecting the tach signal and just the VCC, GND and PWM cables connected.

Yes.

@reneas

Can you help me out with the correct configuration?

As said, I never used a 4-pin-pwm-fan. You might follow Nicholas Sherlock Driving a 4-pin computer PWM fan on the BTT Octopus using Klipper – Nicholas Sherlock
I think you missed something. Why don’t you post a new config.

[reneas]

Sorry for not responding for so long, I am pretty buys with writing my thesis at the moment.
I will try to set up a config for this setup but after what happened, I am really scared that I will break the MCU again…

[olhev]

PWM fans work with ANY microcontroller and nothing gets fried.

How to interpret the output of a 3-pin computer fan speed sensor?

The tacho signal from the fan just needs a normal I/O pin on the board, with pullup.

The PWM command signal goes to a I/O pin on the board, without pullup.

The VCC and GND go separately to the power supply.

I don’t think any further component is really needed for fans following the official specifications, and indeed I connected one to my board as I recommended and gave no issues.

[hcet14]

@reneas

I am pretty buys with writing my thesis at the moment.

That’s much more important, the best of luck!

@reneas

I am really scared that I will break the MCU again…

If you do the measurements explained above, you should be safe

[reneas]

So now I finished my thesis and finally have some free time to tinker with my 3D-printer again!

This time I want to take it slow, so it can’t go wrong again, so let’s start from the basics:
I connected the input of the buck converter to the input of the MCU and the output of the buck converter to the yellow and black wires of the fan.
The only difference was that I didn’t connect the GND of the fan to the wire BEFORE the buck converter (as shown in the schematic of @hcet14) but rather to the GND out of the buck converter.
The green (tach signal) and blue (PWM signal) wires were not connected, so the fan was spinning freely.

Then I measured the voltages from the 4 different wires to the input of the MCU.

Here are the voltages that I measured:

Green   -   GND     :    0.0
Green   -   VCC     :   14.0 (what is this?)
Blue    -   GND     :    2.9 (is this the 3.3 V logic of the board?)
Blue    -   VCC     :   15.8 (and what is this?)
Black   -   GND     :    0.0
Black   -   VCC     :   23.5 (equals input voltage of MCU)
Yellow  -   GND     :   11.9 (equals output voltage of buck converter)
Yellow  -   VCC     :   11.6 (equals difference between the two above)

I can’t tell if these numbers are out of the ordinary or if everything is fine like this. But I don’t really want to connect anything else before have the confirmation that it is safe.

I think the next step would be to connect the blue PWM signal wire and measuring the voltages between the wires again, like you suggested here, right?

@hcet14

I never tried that setup, therefore @reneas, before you connect the “Tacho” signal behind the diode to your SKR Mini E3 v3.0! Measure the signal with a multimeter. If you measure anything above 3,3V stop immediately and tell us here!

[hcet14]

@reneas

So now I finished my thesis

Congratulations!

Hold on, I have to get back on track.

Can we do it like this

Please make a new table of your measurements regarding the numbers?

I guess you measure zero Ohms (everything is turned off!!!), when measuring between 1 and 3?

By the way, witch special Noctua fan are you using? I guess it was never mentioned here.

Can you also provide your printer.cfg?

[reneas]

Hey thanks!

So yes I am measuring 0 Ohms between 1 and 3.

I am using one NF-A4x10 and one NF-A4x20 fans.
They are 40 mm diameter fans with 10 and 20 mm thickness respectively.

The measurements were made with the buck converter connected and all the other wires disconnected!
They yield:

| From |  To  | Value [V] |
| ---- | ---- | --------- |
|GND   |   2  |  23.6     |
|IN    |   3  |   0.0     |
|1     |   4  |  11.9     |
|      |   5  |   0.0     |
|      |   6  |   0.0     |
|      |   7  |   0.0     |
|      |   8  |   3.3     |
| ---- | ---- | --------- |
|VCC   |   3  |   23.6    |
|IN    |   4  |   11.6    |
|2     |   5  |   14.3    |
|      |   6  |   20.2    |
|      |   7  |   16.5    |
|      |   8  |   15.8    |
| ---- | ---- | --------- |
|GND   |   4  |   11.9    |
|OUT   |   5  |    0.3    |
|3     |   6  |    0.8    |
|      |   7  |    0.9    |
|      |   8  |    3.4    |
| ---- | ---- | --------- |
|VCC   |   5  |    7.1    |
|OUT   |   6  |    8.1    |
|4     |   7  |    8.2    |
|      |   8  |    4.9    |
| ---- | ---- | --------- |
|RPM   |   6  |    8.4    |
|After |   7  |    1.0    |
|5     |   8  |    2.1    |
| ---- | ---- | --------- |
|PULLUP|   7  |    0.0    |
|6     |   8  |    8.1    |
| ---- | ---- | --------- |
|RPM   |      |           |
|Before|   8  |    2.7    |
|7     |      |           |
| ---- | ---- | --------- |

And my printer.cfg is:

printer.cfg (9.9 KB)

Please note that the part about the fans is “under construction” and not really functional right now!

[hcet14]

I’m confused.

Can you disconnect all of it and see if the board is still ok and working?

When you measured, was the fan running or did it stand still?

[reneas]

The board is still fine!

I forgot to mention my measurement setup:
Only 1 and 2 (and 3 & 4) were connected so the fan was running on full speed and I measured on the disconnected cables.

[hcet14]

Jesus, you almost gave me a heard attack
Kind of harsh to do it online and not live.

Do you have an external 3.3V power supply? If yes…

please connect it like this (DON’T connect 6 to 3.3V, 7 to PD0 and 8 to PD2) and provide external 3.3V to 6 and 8. Don’ forget to connect the ground from your power supply to 1 or 3

and measure 5. 6, 7, and 8 to ground. Oh, and measure the external 3.3V source to ground.

Fan NOT running?

[reneas]

@hcet14

Jesus, you almost gave me a heard attack
Kind of harsh to do it online and not live.

Yes true, if you want to come to my city in germany and help me figure it out that would be great!

@hcet14

Do you have an external 3.3V power supply? If yes…

I have a phone charger (5V) and a 5V to 3.3V converter so that should work.

@hcet14

Don’ forget to connect the ground from your power supply to 1 or 3

Since the power from the buck converter is coming through the power of the board (like in the picture) the GND in 1 is definitely connected to the PSU

@hcet14

and measure 5. 6, 7, and 8 to ground. Oh, and measure the external 3.3V source to ground.

Will do that!

@hcet14

Fan NOT running?

What exactly do you mean by that? Is that a question?
Do you mean it could be that the fan is not running because we apply 3.3V to the PWM input and that means the fan is on 0%?

I would measure the whole thing with the power connected so the fan is turned on completely.

[hcet14]

@reneas

Yes true, if you want to come to my city in germany and help me figure it out that would be great!

Wow, pretty long way. I would like to visit Germany.

@reneas

I have a phone charger (5V) and a 5V to 3.3V converter so that should work.

Could you, please measure the voltage before you start!

@reneas

Since the power from the buck converter is coming through the power of the board (like in the picture) the GND in 1 is definitely connected to the PSU

Of course, just make sure the ground from your 3.3V converter is connected to 1 or 3.

@reneas

What exactly do you mean by that? Is that a question?

No, an expectation.

@reneas

Do you mean it could be that the fan is not running because we apply 3.3V to the PWM input and that means the fan is on 0%?

That’s what I expect.

@reneas

I would measure the whole thing with the power connected so the fan is turned on completely.

Hold on, if this comes out as I expected, we’ll try something else. I’m very curious.

[mykepredko]

@hcet14

@reneas

I have a phone charger (5V) and a 5V to 3.3V converter so that should work.

Could you, please measure the voltage before you start!

@reneas

Since the power from the buck converter is coming through the power of the board (like in the picture) the GND in 1 is definitely connected to the PSU

Of course, just make sure the ground from your 3.3V converter is connected to 1 or 3.

How about a wiring drawing and pictures? We’ve had concerns regarding how things are wired this whole thread.

[hcet14]

@mykepredko

How about a wiring drawing and pictures? We’ve had concerns regarding how things are wired this whole thread.

@hcet14

I’m very unsure how to answer. I don’t understand your expectations. What is your concern?

[mykepredko]

“Ground from power supply”.

I would recommend that you use the 24V Negative Voltage (“Ground”) rather than the 12V Negative Voltage one - unless you’re absolutely sure there is no voltage offset between the 24V Negative Voltage and there is a direct connection to it.

If there is a direct connection between the 24V Negative Voltage and the 12V Negative Voltage then delete the common connection between the two of them outside the 24/12V DC/DC converter.

[hcet14]

Ok, I understand.

@mykepredko

I would recommend that you use the 24V Negative Voltage (“Ground”) rather than the 12V Negative Voltage one - unless you’re absolutely sure there is no voltage offset between the 24V Negative Voltage and there is a direct connection to it.

We might ask @reneas which special converter is used, but he said

@reneas

So yes I am measuring 0 Ohms between 1 and 3.

So I’m ok with that.

[mykepredko]

Sorry, I should have gone back further in the thread.

I was asking @reneas for a drawing because of this exchange:

Now, add the 24V/12V DC/DC, it’s a pretty wild circuit.

I’d still recommend that @reneas share exactly what he’s doing because it sounds like there’s a real hodge-podge of power supplies.

[hcet14]

Proposal for clearness

We don’t want to use the 3.3V from the board for our test. See

@reneas

Okay so today I tried this setup and it broke my motherboard…

The phone charger (5V) seems to be his only 5V source.

@reneas

have a phone charger (5V) and a 5V to 3.3V converter so that should work.

Using this dirty 5V source with the 5V to 3.3V converter is good enough for this little test. That’s why I asked

@hcet14

Could you, please measure the voltage before you start!

I think we’re cool.