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I have a feeling I'm not unable to do this but I would still rather ask the more knowledgeable folks just in case I'm either wrong or you happen to have an alternative suggestion.

I have my RP4 on a case with a miniature 5V cooling fan and I want to add this fan controller so I can control the fan speeds. However, I would also like to add a tiny screen such as the Adafruit PiOLED but as far as I understand these pins are already taken by the fan.

Am I correct? In that case, are there any other simple ways around adding this or something similar?

Thanks in advance for the help.

Edit 1:

So I moved the fan to the 3.3V GPIO pin 17 and Ground pin 20 and it still works albeit at a lower speed, which is great. However, I've tried to add dtoverlay=gpio-fan,temp=60000 to the config.txt expecting a on/off situation but it seems to remain always on, even after updating, upgrading and rebooting.

I would be happy settling with the fan only triggering when reaching the previously defined 60C as I've already managed to free the pins to add the PiOLED.

Edit 2:

The PiOLED seems to use the GPIO pins 1-6 but this 5V Controllable Fan seems to use the GPIO pins 4, 6 and 8. When checking Pinout, it looks like I could possibly keep the UART TX on pin 8, move GND to pin 9 and the 5V to 3.3V on pin 17. This would be on less power but I would be ok with that as long as it's not an issue.

Would this be ok or is this train of thought incorrect?

bakashinji
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1 Answers1

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These both appear to use I²C which is a shared resource so they could in principle be shared.

Whether this is mechanically possible is doubtful although you could solder the pins.

You certainly don't NEED a fan controller; there is kernel fan software builtin and you could use a transistor to turn fan on/off.

I doubt that you actually need a fan - the Pi runs most tasks without overheating.

Milliways
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  • My understanding is that this fan is either on or off without any control in middle as it is.. Even when I shutdown the Pi the fan keeps spinning. I'll give the recommended link a go and report back though. Thanks – bakashinji Nov 14 '23 at 08:15
  • You can not control the speed of a 2 wire fan (at least with any reliability). It will turn on if temp is exceeded and off once the temp is lowered. NOTE any additional detail belongs in your Question NOT Comments – Milliways Nov 14 '23 at 11:11
  • Apologies for the post etiquette. I've edited the Question to address this. – bakashinji Nov 15 '23 at 17:25