MrCrypDough
Posts: 21
Joined: Sun Jul 11, 2021 4:46 pm

Out of GPIO pins for mini 1.3" display screen. Need help troubleshooting current possible solution (a fan hub)

Wed Sep 22, 2021 6:50 pm

Hello and good morning all! So I am trying to free up some gpio pins so that I may get a display connected. Currently, I have accessory fans using the gpio pins. (They are built into the housing case for a handful of raspberry pi). I have a powered fan hub chassis that I thought was going to work to power the fan and lights built into the fans. It has no problem with powering the lights, it will power the fans (but the fans will only pulse; I want them to always run.) My current set up is such that I am powering the lights with the fan hub (which is connected to a PSU: no motherboard or CPU is attached.), and I power the fans with the gpio pins on the pi. I want to power everything from the fan hub (connected to a PSU w/o a motherboard.) I have bypassed the requirement of having the PSU plugged to a motherboard by connecting two of the pins in the plug that would go to a motherboard. I will attach picture below. I just need help figuring out how to make everything work from the fan hub. To clarify, I know I could do some work around to still get a display connected to the gpio pins with currently using the pins I am now; however, I am trying not to draw any more power from the pi itself. I just need to know how to keep the fans from only pulsing, they must run all the time (without the need of a motherboard or CPU).
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MrCrypDough
Posts: 21
Joined: Sun Jul 11, 2021 4:46 pm

Re: Out of GPIO pins for mini 1.3" display screen. Need help troubleshooting current possible solution (a fan hub)

Wed Sep 22, 2021 6:51 pm

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aBUGSworstnightmare
Posts: 3633
Joined: Tue Jun 30, 2015 1:35 pm

Re: Out of GPIO pins for mini 1.3" display screen. Need help troubleshooting current possible solution (a fan hub)

Wed Sep 22, 2021 7:06 pm

Better let us know what a 'fan hub' is. Also can't get the point of what is shown on the pics.
Specs for fans and LED are also considered usefull ...

MrCrypDough
Posts: 21
Joined: Sun Jul 11, 2021 4:46 pm

Re: Out of GPIO pins for mini 1.3" display screen. Need help troubleshooting current possible solution (a fan hub)

Wed Sep 22, 2021 7:41 pm

aBUGSworstnightmare wrote:
Wed Sep 22, 2021 7:06 pm
Better let us know what a 'fan hub' is. Also can't get the point of what is shown on the pics.
Specs for fans and LED are also considered usefull ...
Right, That is a fair point! So the fan hub is designed to be used with a main computer to hook up multiple case fans and be able to control them from the motherboard with the bios. The fan hub is capable of powering up to 10 fans. It is powered by a 4 pin miles to a PSU, of the 10 four pin input connectors for the fans, 1 of them is designed to control a CPU fan (I do not have a CPU connected to this. The fan hub works such that, when the CPU fan is connected to the fan hub, you can control this fan and the other 9 fans will be controlled in unison (not separately). So I have nine fans hooked to the fan hub, these fans are a standard 5 V fan that has RGB LEDs built into them. The fan hub is designed for a standard four pin fan, the fans that I have are two pin fans with GPIO connectors. The way the fans are designed is two of the female GPO connections are meant to power the fan (5v and a ground) and two of the female GPIO connections are meant to power the LEDs (5v and a ground). Both the fan and LEDs are capable of running on 3.3v as well. When I plug all four of the GPIO from fan to fan hub, it powers the LEFs and fan (but the fan only pulses instead of continuously running). The fan hub requires a power source, hence the PSU, it also typically requires being plugged into A motherboard or CPU to be able to link them to the bios and control them. I have bypassed this requirement by connecting two of the female pins on the 20 pin (might be 26 pin) with a copper wire. This is shown in one of the pictures with the yellow wire. I can easily power the led and fan with the pins on the pi, but I need the pins for a display screen and a cooling tower, (I understand the extra fans are overkill, it is more for looks). I will link the fan hub and the fan case I am using.

Fan hub:
Electop PC Chassis Fan Hub CPU... https://www.amazon.com/dp/B071KNT7FW?re ... b_ap_share

Fan/case:
GeeekPi New Raspberry Pi Cluster... https://www.amazon.com/dp/B08FH3V6GV?re ... b_ap_share

What else do you need to know?

aBUGSworstnightmare
Posts: 3633
Joined: Tue Jun 30, 2015 1:35 pm

Re: Out of GPIO pins for mini 1.3" display screen. Need help troubleshooting current possible solution (a fan hub)

Thu Sep 23, 2021 6:36 am

https://wiki.52pi.com/index.php/Rack_To ... U:_ZP-0108

Baeed on the avove info your fans don't have a PWM input capability.

The pinout of your fanhub is following the ATX fan spec most likely https://allpinouts.org/pinouts/connecto ... 4-pin-fan/. Will only work for fans with PWM input capability, others will run at full speed only (read the product description, mentioned there as well).
If you connect your LEDs to the headers connect tme to 5V/GND, not the other pins!

Of particular interrest https://developer.nvidia.com/embedded/l ... Header(J7)

what do you want to achieve with your setup?

MrCrypDough
Posts: 21
Joined: Sun Jul 11, 2021 4:46 pm

Re: Out of GPIO pins for mini 1.3" display screen. Need help troubleshooting current possible solution (a fan hub)

Thu Sep 23, 2021 8:50 am

aBUGSworstnightmare wrote:
Thu Sep 23, 2021 6:36 am
https://wiki.52pi.com/index.php/Rack_To ... U:_ZP-0108

Baeed on the avove info your fans don't have a PWM input capability.

The pinout of your fanhub is following the ATX fan spec most likely https://allpinouts.org/pinouts/connecto ... 4-pin-fan/. Will only work for fans with PWM input capability, others will run at full speed only (read the product description, mentioned there as well).
If you connect your LEDs to the headers connect tme to 5V/GND, not the other pins!

Of particular interrest https://developer.nvidia.com/embedded/l ... Header(J7)

what do you want to achieve with your setup?
The end goal would be having the fans running at full speed all the time. When I plug the 5v and ground for the LEDs and the 5v and ground for the fan motor to the fan hub, the fans only pulse on and off (the LEDs do work though). This is what I am trying to fix, there is no problem for me to run them at full speed, they are low rpm fans anyways. So, yes there is no pwm capabilities of the fans. I want to be able to power the LEDs and the fan to the same input on the fan hub. The fan hub is ultimately a cable management solution to me. It also allows me to keep the power draw off of the rpi. The big picture end to this project is a supercooled cluster of rpi running exsi. The cluster is meant to be where I build some virtual machines, at some point they will be introduced to a far more powerful machine capable of hosting multiple virtualized clusters of machines. This is very far down the road though, I have much more learning and many more components to buy and build. Is there a way to ground out the pwm on the plug that would connect to the header on a motherboard and keep the fans from pulsing on and off (keep in mind I am bypassing using a motherboard).

MrCrypDough
Posts: 21
Joined: Sun Jul 11, 2021 4:46 pm

Re: Out of GPIO pins for mini 1.3" display screen. Need help troubleshooting current possible solution (a fan hub)

Thu Sep 23, 2021 9:26 am

aBUGSworstnightmare wrote:
Thu Sep 23, 2021 6:36 am
https://wiki.52pi.com/index.php/Rack_To ... U:_ZP-0108

Baeed on the avove info your fans don't have a PWM input capability.

The pinout of your fanhub is following the ATX fan spec most likely https://allpinouts.org/pinouts/connecto ... 4-pin-fan/. Will only work for fans with PWM input capability, others will run at full speed only (read the product description, mentioned there as well).
If you connect your LEDs to the headers connect tme to 5V/GND, not the other pins!

Of particular interrest https://developer.nvidia.com/embedded/l ... Header(J7)

what do you want to achieve with your setup?
Is there such a thing as 2 pin fan hub chassis? Or some compact power splitter for just a 5v and ground? I would need to fit 18 5v and 18 ground wires then. It would also need to be able to connect to a PSU.

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