Raspberry Pi won't boot with UART connected

I’m testing a Raspberry Pi 3B+ hooked up to one of these UPS devices: UPSPACK_V3/README_en.md at master · rcdrones/UPSPACK_V3 · GitHub . When I connect up the GPIO wiring, the device hangs during boot:

My config.txt has UART enabled and SERIAL-CONSOLE is set to “off” in uEnv.txt. Are there any additional configuration changes I would need in order to make this work? I have not installed any additional scripts, this happen just when the wiring is hooked up.

(Thankfully I was smart enough to test this outside my normal firewall!)


Change SERIAL-CONSOLE=ON and give that a try.

I will give it a try, but I’m not super hopeful. When I was testing this with a standard Pi OS image, I had to turn off serial console or things got strange. The issue seems to be that serial console is kind of about “sending” information out of the Pi, while this UPS wants to “send” information to the Pi. Confusion ensues.

Tested and get the same behavior with serial console set OFF or ON.

u-boot use the serial console always as input. If a character is recieved it will disable the autoboot. I think this usv is incompatible with u-boot.