Weird power on behaviour

[lormaccone]

I have the esp32 devkit board connected to a ws2812b led array, an audio amplifier connected to a dac input io, and a rotary encoder.

When I give power (5V) to the circuit the FIRST time, nothing happens. If I remove power and apply it again, everything works properly. All successive times I switch on and off, everything works fine. BUT if I leave it off for many (>8?) hours, then again, the FIRST time I switch it on it fails, the second and successive ones, everything works properly.

It's NOT the power supply, I've tried many different ones (including a 30 amps one!). Indeed if I use one power supply at the first switching on, and then change power supply before switching on the second time, everything works the second time. Even if the first time I connect it to the PC with a usb cable, the first time I connect it it doesn't work, the second it does.

It's very difficult to debug, as I have to wait hours to reproduce it, and I cannot use the serial monitor as I need to connect it to a PC (i.e.power it on) to do it.

WHAT ON EARTH CAN KEEP MEMORY OF THE LAST POWER ON in this circuit, which can be reset only after hours of power off?!? There are no (large) capacitors or anything in the whole circuit...

Thanks for any hints! I'm really lost here,
Lorenzo

[ESP_Sprite]

Possibly a power supply rails that for some reason rises too slowly. You could try adding e.g. a 4.7uF capacitor beteen EN (reset) and GND, see if that fixes it.

[lormaccone]

I'll try that, but I'm not optimistic: if that was the problem, it would depend on the power supply, which it doesn't. Thanks!

[lormaccone]

It worked!!!! Thank you thank you thank you thank you!! You rock, thanks!
Lorenzo