<p>Servo pins are PWM pins, so yes <code>D11</code> can be used, but not directly connected to the fan as the pins only allow a very low current. You'll need a MOSFET to drive the fan. You don't need 4-pin fans, 2-pin fans will suffice.</p>

CC BY-SA 4.0
2022-06-12T04:59:13.053Z
2022-06-12T04:59:13.053Z
0scar
<p>I have radial fan with 2 pins connector and always kept it connected to <code>GND</code>/<code>5V</code> pins (marked J5 at the left bottom on pinout image for my controller board).</p>
<p>I've stumbled upon the <code>USE_CONTROLLER_FAN</code> feature of Marlin which allows setting some pin to be used for PWM-controlling a control board fan. I think <code>SERVO0_PIN</code> should do fine (<code>D11</code> at the bottom center on the pinout image), but I'm not sure how to connect it.</p>
<ol>
<li>Should I split connector and use <code>GND</code> + <code>D11</code> pins?</li>
<li>Or should I use some proper PWM fan for that (which are always 4pin and then how would one connect THAT to those pins?)</li>
<li>Is it safe to run a fan directly from board pins or should I resort to using either unused MOSFET outputs (e.g. <code>FAN</code> MOSFET pin marked as <code>D9</code> on the left)?</li>
<li>Should I use dedicated MOSFET board to drive that fan using that SERVO0_PIN?</li>
</ol>
<p><a href="https://i.sstatic.net/u0kzf.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/u0kzf.png" alt="MKS GEN v1.4 board pinout" /></a></p>

<marlin><wiring><fans>
Connecting controller fan on RAMPS 1.4 for Marlin
Eduard Sukharev
# Connecting controller fan on RAMPS 1.4 for Marlin

(Asked by: username_0 on 2022-06-11)

I have radial fan with 2 pins connector and always kept it connected to `GND`/`5V` pins (marked J5 at the left bottom on pinout image for my controller board).

I've stumbled upon the `USE_CONTROLLER_FAN` feature of Marlin which allows setting some pin to be used for PWM-controlling a control board fan. I think `SERVO0_PIN` should do fine (`D11` at the bottom center on the pinout image), but I'm not sure how to connect it.

1. Should I split connector and use `GND` + `D11` pins?
2. Or should I use some proper PWM fan for that (which are always 4pin and then how would one connect THAT to those pins?)
3. Is it safe to run a fan directly from board pins or should I resort to using either unused MOSFET outputs (e.g. `FAN` MOSFET pin marked as `D9` on the left)?
4. Should I use dedicated MOSFET board to drive that fan using that SERVO0\_PIN?

[![MKS GEN v1.4 board pinout](https://i.sstatic.net/u0kzf.png)](https://i.sstatic.net/u0kzf.png)

**Tags:** marlin, wiring, fans


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## 1 answers

### Answer by username_1 on 2022-06-12. Score: 1 | Accepted answer

Servo pins are PWM pins, so yes `D11` can be used, but not directly connected to the fan as the pins only allow a very low current. You'll need a MOSFET to drive the fan. You don't need 4-pin fans, 2-pin fans will suffice.


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