Another RPI 5 question. Have any developers attempted to overcome the power limitation issues with the RPI 5 by using the USB C PD along with a external powered RPI 5 M2 Hat?
I have been considering using the Geekworm X1001 PCIe to M.2 HAT Key-M NVMe SSD PIP PCIe Peripheral Board with the external power connector but am concerned about current flowing back into the RPI 5 through the PCIe cable.
I tried powering both the RPI 5 and Metis M2 board by applying 5V with a 5A limit (5A being the limit of my bench supply) to the 5V GPIO connector pin but the RPI 5 did not boot correctly. I suspect it’s an issue with the inrush current demands of the RPI 5 and Metis M2 together exceeding 5A.
Thank you for your help!
RPI 5 external power M.2 Hat with Metis 2
+2- Axelera Team
Ah, interesting issue. From what I can find, the Geekworm X1001 can only deliver max 5W via the FFC PCIe ribbon. And if I remember correctly, the PRi5 requires USB-PD negotiation to recognise a 5A supply, otherwise it defaults to assuming 3A (that needs double checking, mind you).
As you say, and initial current surge could briefly top 5A, and I’m also not sure if there’s a diode in place to prevent any potential reverse current. I have a suspicion there wouldn’t be…
I think you can add someting like PSU_MAX_CURRENT=5000 to the Pi’s eeprom config that ensures it defaults to 5A, rather than 3A. Maybe that’d get you over that initial boot hurdle, but please do check that out in some RPi docs beforehand, just to be sure it does as we’re hoping. Keep me posted!
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