Beginners • Re: Raspberry Pi 5 OTG USB ports?

After buying this product (https://www.amazon.ca/dp/B0CSVYFRYQ), I am now getting the low voltage alert on my OS.
So I bought this other product (https://www.amazon.ca/dp/B07TS17VB9), the voltage drops in fact by .6
From 5.1 to 4.5
Would anyone have a usb c hub to recommend, like a tried solution?
Because this hub was rated as 100w capable, and I am using the official power supply which only pumps up to 27w.
I even bought a 100w power supply to try to make it work, however the voltage remains inferior to what it's supposed to be.

For Pi gadgets one only needs a USB 2 hub. This is because the USB C sockets are only USB 2.

Since USB 2 hubs are simpler, they're easy to pry apart and separate the power from the data lines.

I successfully modified four hubs of this type


https://www.amazon.com/Sabrent-Portable ... 00L2442H0/

to power twelve Pi 4 computers and for Pi Zeros when building a micro cloud in a 2U chassis.

viewtopic.php?p=1690607#p1690607

Maybe I'm misunderstanding you but, when I plug the official power supply to a USB 2 port (with an adapter) the pi doesn't turn on.
And looking at the pictures from the thread you posted, all the pis seem to be connected through usb c?

In reality, all I did was turn a cheap bus-powered hub into an externally powered hub. Any good externally powered hub should also work, but I found it difficult to find one that delivers sufficient current at 5V to power even one Pi 4.

I'll try to explain with a diagram of the modified hub:

The above image may be reversed as I'm reproducing it from memory rather than looking at an actual hub right now. Check what's what before cutting.

The modification proceeds as follows:

• Pry the USB hub apart at the seams. With this particular hub there is no glue or fasteners that need to be cut or released. It will just come apart.
• Cut the wire for the 5V arriving from the USB host and tape it off.
• Cut the 5V pin for each of the four USB sockets at the base of the circuit board, for example with a sharp razor blade. Bend them outwards.
• Run a thick red wire--I used 18 AWG solid copper core--from the external 5V power supply. A single wire with insulation stripped at the appropriate points in the middle can be used.
• Run a thick black wire from the external 5V power supply. Connecting it directly to the ground pins on the sockets might have been better, but I soldered the ground wire to the metal housing on the back side of each socket.
• I managed put the circuit board back in the original housing with a hole at the far end for the red and black wires.

The above worked for me, but there may be specific details in my setup which are different than yours. For example, I used 5V from the same ATX power supply that was used to power the host and did not worry about ground loops. Note that I also included a fast blow fuse on the 5V wire (not shown) to hopefully avoid setting things on fire in case of short circuits.

With such a modified hub it was possible to plug the Pi computers into the hub using 6 inch USB A to USB C cables. At this point the Pi received sufficient power from the external 5V source, could load a kernel and initial RAM filesystem over USB using rpiboot and then switch to gadget mode as a USB Ethernet device.

Wiring up four such hubs allowed connecting twelve Pi 4B and four Pi Zero computers as gadgets to a single x86 host. Even so, I'd be hesitant to connect more than two Pi 5 computers to such a modified hub. Also, in case it wasn't clear already, the above modification is not likely compliant with USB standards and may not show good electrical judgement, even with the fuse of the 5V wire.

Any ideas for improvements are welcome.

Statistics: Posted by ejolson — Tue May 14, 2024 3:49 am

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