Powering the dev kit v4 with 5V; sometimes, FW won't start

[barafael]

I am powering my project with USB during development. That works really well.

But when I test if it works with the lab power supply on the 5V pin, it does not work sometimes. The red power supply comes on always, though. When I attach the USB additionally (I know I shouldn't) it starts working immediately. The only pins I am using are 5V, GND, 26, 32, 13, 25, 27, 33.
Anything obvious I'm doing wrong here?
Thanks,
Rafael

[felmue]

Hello @barafael

I wonder if the auto download mechanism somehow holds the board in reset (EN low) when powered from external 5V? Maybe check EN with a multimeter?

Also there seems to be a possible issue with earlier boards, where it boots into download mode. https://docs.espressif.com/projects/esp ... ote-on-c15

Thanks
Felix