I am using a Pi4 4GB as a controller for my 3D printer using Klipper.
The Pi4 is powered by a 5V 5A power supply. Connected to the Pi4 via USB is a tool head board (LDO Nitehawk36) which uses a RP2040 as an additional MCU.
My problem is that the Pi4 will not boot when the RP2040 is connected. I just get a solid red power light with no activity. As soon as I unplug the 2040 board the activity light comes on and the system boots fine. I can plug the 2040 board back in at this point and everything is absolutely fine.
But this isn't something I can do every time I switch it on.
Does anyone have any ideas why having the RP2040 connected would prevent the Pi4 from booting? Any solutions I can try?
I don't have any answers.
But just adding this Documentation to save lots of volunteer helpers going looking for it.... Ref: Nitehawk-36 Toolboard - https://docs.ldomotors.com/en/Toolboard/nitehawk-36
And noting that USB Adapter board needed as part of the installation, which needs its own independent power supply, I would wonder whether it is 'backfeeding' power over the usb connection to the host RPi board and causing a conflict at boot-time? What, specifically, do you unplug to allow normal booting of the RPi4 to proceed? Have you tried powering the RPi4 solely from the LDO Nitehawk36 adapter with the 'dedicated' RPi4 5v power disconnected?
(And I think this would be better headlined as an LDO Nitehawk36 issue: it seems only incidental that it is implemented using an rp2040 microcontroller.)
Statistics: Posted by B.Goode — Fri Aug 29, 2025 4:17 pm