lolin d32 pro needs pin0 pulled down to flash

[gdanov]

I'm using two identical lolin boards as in the title to develop basic controller (thermo sensor, ssr, dimmer periphery) and every now & then they start requiring pin0 to be pulled down in order to flash. The tty works without problem.

when this happens typically the board is connected to a raspberry-pi clone (cubieboard) running armbian. same board connected to my laptop flashes without problem. Using extremely short usb cable (10cm) sometimes help, but not always. the usb host provides 5.1v, verified with tool.

looks like sort of mystical electrical problem which I don't even know where to start debugging. I plug my esp32 board into prototype board I've done. Even when the board is stripped of all peripherials the problem persists. It appears like the USB modem can't reset the board. If needed I can provide dump from esptool communication.

[ESP_Sprite]

Probably an auto-reset timing issue. Try to add an 10uF capacitor between the EN (=/RESET) line of the ESP and ground.

[gdanov]

thanks, this solved it!
added 4.7uf capacitor GND <> RST and reset works as expected.

plus part of the annoying whine coming from the cubieboard is gone. very weird?