Boot from SD Card when Powering from GPIO

#1

Hello,

I have been trying to power the Radxa Zero 3W through a board which powers the Radxa through the 5V GPIO pins. However, it does not seem to boot, the LED turns on and stays on. When the board is powered through the USB-C port, the OS boots and the LED starts blinking.

I think the board may be defaulting to booting off the eMMC storage (which I did not setup) when powered by the GPIO pins?

Any help would be much appreciated. Thank you!

Nick

Edit : Interesting behaviour. The Radxa won’t boot if I mount it on my board then plug in USB-C (no power from my board), the LED just stays on with no display output. However, if I plug in USB-C when it is unmounted, it boots just fine, and then if I mount the Radxa on my board after it is on, it functions just fine. So it can run mounted on my board, just can’t boot.

#2

Not exactly what you are looking for … I don’t have problems powering my Zero 3Es through the 5V GPIO pins. Though, the 3Es don’t have eMMC.

Briefly looking at the schematics of the 3W, the 5V GPIO and VBUS (from USB-C port) are connected together. So, at least the hardware shouldn’t know how it is powered.

#3

Thank you @bartsch, I didn’t realize they had the schematics available. I believe a solid light also may mean maskrom is being run, so I will check if that’s linked up to anything in the schematics.

Thanks again!

Nick

Edit2: I am stupid, my model of Zero 3W doesn’t even come with eMMC (was wondering where the button was >_<). So I’ll need to look elsewhere.

Edit1: It doesn’t seem like anything from the 40-pin header can interfere with starting maskrom.

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