Silcat
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Raspberry Pi Fan

Wed Jun 22, 2022 7:11 pm

Hi! I got a fan for my Pi 4, and I put it on GPIO pins 2 and 6. (I checked what each GPIO pin was and it was 5V power and ground.) I powered my Pi up and the fan did not work. I checked the settings and the fan was enabled and set to GPIO 2, with the power on temperature 60. I got curious and ran the check temperature command on the Pi, which was over 100 degrees. So I'm not sure if the fan is just bad and I should return it, or if it's just I'm putting it in the wrong GPIO pins and have the wrong settings. Please Help!

klricks
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Re: Raspberry Pi Fan

Wed Jun 22, 2022 8:14 pm

Silcat wrote:
Wed Jun 22, 2022 7:11 pm
Hi! I got a fan for my Pi 4, and I put it on GPIO pins 2 and 6. (I checked what each GPIO pin was and it was 5V power and ground.) I powered my Pi up and the fan did not work. I checked the settings and the fan was enabled and set to GPIO 2, with the power on temperature 60. I got curious and ran the check temperature command on the Pi, which was over 100 degrees. So I'm not sure if the fan is just bad and I should return it, or if it's just I'm putting it in the wrong GPIO pins and have the wrong settings. Please Help!
The fan settings in raspi-config are intended for use with the official 3 wire fan and will not work with a 2 wire fan: https://www.raspberrypi.com/products/ra ... -case-fan/
A 2 wire fan should always be on as long as power is connected to the RPi and can't be controlled.
Does the RPi work?
Unless specified otherwise my response is based on the latest and fully updated RPi OS Bullseye w/ Desktop OS.

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HawaiianPi
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Re: Raspberry Pi Fan

Wed Jun 22, 2022 9:34 pm

Silcat wrote:
Wed Jun 22, 2022 7:11 pm
Hi! I got a fan for my Pi 4, and I put it on GPIO pins 2 and 6...

I powered my Pi up and the fan did not work. I checked the settings and the fan was enabled and set to GPIO 2...
There is a difference between a GPIO 2x20 header pin, and a GPIO input/output number (Pin #2 is not GPIO #2, they are not the same). The 5V and Ground pins are not General Purpose Input Output pins (they are not controllable).

As klricks said, that configuration setting is specifically for the Raspberry Pi 3-wire Case Fan. It will not work with any other 3-wire fan (although some 4-wire fans can be modified to work).

Fans with only 2 wires will always run when the system is connected to power (even when it's shutdown or sleeping). They are not controllable without additional circuitry.
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rpdom
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Re: Raspberry Pi Fan

Wed Jun 22, 2022 9:38 pm

Silcat wrote:
Wed Jun 22, 2022 7:11 pm
I got curious and ran the check temperature command on the Pi, which was over 100 degrees.
Is that 100°F or 100°C?
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HawaiianPi
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Re: Raspberry Pi Fan

Thu Jun 23, 2022 12:31 am

rpdom wrote:
Wed Jun 22, 2022 9:38 pm
Is that 100°F or 100°C?
Good point. Being from the US that didn't catch my attention, but if that's 100°C then something is very wrong!

@Silcat,
Pi computers will throttle performance (slow down) to prevent them from getting that hot. Most start to throttle at 80°C and they fully throttle at 85°C, so you should never see temps much higher than that.

If it's 100°F then that's not even hot for a Pi (80°C = 176°F and that's just where they start to throttle).
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Silcat
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Re: Raspberry Pi Fan

Thu Jun 23, 2022 4:49 pm

For one of your questions, the Pi gave it to me in Celsius, so I converted it to Fahrenheit. so yes, it is 100 degrees Fahrenheit. also, good to know those settings were not important. so it seems my fan is just not working. is there a way to solve this problem or should I get a new fan?

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onebitcpu
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Re: Raspberry Pi Fan

Thu Jun 23, 2022 5:47 pm

What voltage is the fan rated at? Pin2 provides only 5 volts.
I've found that you can drive a 5v fan on 3 or 5v, but an old 12v fan I had did not run on 5v.
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Silcat
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Re: Raspberry Pi Fan

Sat Jun 25, 2022 1:18 am

Well, it has 2 options. you can put it in GPIO pins 2 and 6 for 5v, or 1 and 6 for 3.3v.

Silcat
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Re: Raspberry Pi Fan

Mon Jun 27, 2022 9:00 pm

I am sorry, but it turns out I was putting the pins on the wrong side.

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CaptainMidnight
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Re: Raspberry Pi Fan

Tue Jun 28, 2022 4:28 pm

HawaiianPi wrote:
Wed Jun 22, 2022 9:34 pm
It will not work with any other 3-wire fan
Just to clarify your earlier point, I've had no issue using cheap 3-wire fans with the inbuilt raspi-config functionality, although I prefer my own python code with multiple temp/speed settings ;)
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HawaiianPi
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Re: Raspberry Pi Fan

Tue Jun 28, 2022 9:57 pm

CaptainMidnight wrote:
Tue Jun 28, 2022 4:28 pm
Just to clarify your earlier point, I've had no issue using cheap 3-wire fans with the inbuilt raspi-config functionality...
How do you control "cheap 3-wire fans" when the 3rd wire is a tachometer wire, which is only for measuring speed (not controlling it)?

You usually need a 4 wire fan to have the PWM wire (the Raspberry Pi Case Fan being an exception), or you need additional circuitry.
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gordon77
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Re: Raspberry Pi Fan

Wed Jun 29, 2022 6:06 am

Here's one example of a cheap 3 wire controllable fan ..

https://thepihut.com/collections/raspbe ... controlled

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CaptainMidnight
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Re: Raspberry Pi Fan

Wed Jun 29, 2022 7:13 am

gordon77 wrote:
Wed Jun 29, 2022 6:06 am
Here's one example of a cheap 3 wire controllable fan ..

https://thepihut.com/collections/raspbe ... controlled
+1

Before the launch of the Raspberry Pi official case fan modification, raspi-config was updated to offer the single temperature fan control - that was like waving a red flag to a bull for me as a challenge, found some cheap 5v 3-wire fans online and started testing ;)

Then not long later PiHut and the other main online Raspberry Pi sellers started to list the same fans.
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HawaiianPi
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Re: Raspberry Pi Fan

Thu Jun 30, 2022 5:59 pm

Ah, okay, I wasn't aware of anything other than the Raspberry Pi Case fan that had a 3-wire configuration with a control wire. However, those are special fans specifically designed to work with Pi computers, they are not standard 3-wire fans, so they're in the same category as the Raspberry Pi case fan.

You can't control a typical/common 3-wire fan (without additional hardware).
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