ESP32 auto reset circuit

[Roberthh]

I use the --noreset option of picocom, which connects and leaves silently without touching the modem control lines. e.g.:

picocom -b 115200 --noreset /dev/ttyUSB0

But I am not sure that a reset will never happen.

[tve]

It sounds to me like you have two USB use-cases: plug-in to troubleshoot without reset, and plug-in to develop/upgrade where reset is desired. I would use a physical jumper on the reset line. Without jumper no reset, no matter what typo you make on the commandline. When you want to reflash, etc, insert the jumper and hack away.

[danielm]

@Roberthh
Reset is triggered immediately after the the FTDI chip is connected to USB cable/host. The chip is powered from bus. I think it is related to power-on state/sequence of DTR and RTS pins.

@tve
You are right regarding two use-cases of the interface.
The idea was not to expose reset and flash switches (or any jumpers) on the housing of the device so it would not confuse the user and also make flashing process easier. It would also help to avoid unintentional resets of the device during continuous operation which could happen if reset switch would be exposed.

[danielm]

I managed to find some solution. I will see in the future if it is reliable enough.

It is described here:
https://www.esp32.com/viewtopic.php?f=12&t=15461