I would like to use an external device to reset my Electron but I only have access to 5V digital pins on that device.
Is the RST pin on the Electron 5V tolerant ?
I wouldn’t thinks so, since it has an internal pull-up to 3.3V which is an exclusion factor on the otherwise 5V tolerant GPIOs.
You’d permanently feedback from your 5V signal to the 3.3V rail via the pull-up resistor.
That should work.
What kind of signal pin are you dealing with? If it’s a GPIO of some sort (like from an Arduino) you could have it high-z and only got to output LOW when you want to reset.