RPi Zero with a USB Hub connected to Prusa Einsy RAMBo board causes printer not to boot

Hello everyone,

I have attempted to connect a RPi Zero board to my Prusa MK3S+ machine running Octoprint as described in this post: PrusaPrint (Rpi Zero and Octoprint) | Prusa Knowledge Base

This setup worked fine but then I attempted to add 4 x USB Hub to the RPi Zero but this caused the Prusa printer not to boot when I switched on the PSU. The LCD remained dark and it seemed like the printer received no power. I have tried to re-solder the pins and tried with different board but it did not help.

This is the USB Hub I used: WaveShare USB HUB HAT (B) for Raspberry Pi Series, 4x USB 2.0 Ports 2, 7,99 €

I have read that the Einsy board can provide up to 2A over that connection, however the RPi draws very little (around 400mA) and there is nothing connected to the USB hub that would draw extra electricity.
The setup works fine when I provide power to the RPi over my laptops USB port.

Currently, I have an idea to connect the RPi to the PSU unit over a 24 to 5 V converter but I'm not sure if it'll work properly since the RPi is already connected to the 5V on the Einsy board. I am trying to keep the setup lean and clean and this approach has additional components which I don't prefer but will have to use if there is no other way.

Do you know what could be the issue and how to fix it? Is the idea to add PSU power to RPi dangerous to the board?

Thanks for the replies :slight_smile:

Not sure what the issue is, but are you sure it's power related? Reason I ask is because this neat little hub backpack also uses GPIO connection to create the data link for USB. I do know there are several people that have used step down converters to convert 12v/24v printer power to 5v power for the pi directly without issue, the trick is making sure you get enough amperage. The original zero (you didn't state which model), which is unsupported by OctoPrint, requires 1.2A while the Pi Zero 2 W requires a 2A power supply. What you might be running into is the hub taking just enough power away to put it just under the 2A required by the pi.

The model is RPi Zero W, thank you for pointing out the lack of that info. I assumed that the issue is power related because when I applied power over microUSB RPi port everything worked fine.

The main issue is that the printer doesn't receive enough power. I haven't tested if the RPi receives enough power but will do that soon.