Re: ESP-01 won't stay turned on unless I short EN+RST
Posted: Sat Aug 15, 2020 5:40 pm
One of the advantages of not having a pull up on the module for EN is that it gives more flexibility if you want to use this pin for things like externally waking up from deep sleep. The EN pin is intrinsically a very high input impedance input and having a low value pull up built in reduces some of the possibilities for interfacing. A free EN pin is used on all ESP-12 modules.
If not planning to use EN for wake up then it is actually safe to just connect it to the Vdd (3.3V) as it is a pure input. That doesn't apply to the other pins like GPIO15 or GPIO0 where connecting to Vdd or GND carries the risk that the program may configure the pin as an output and then try to drive into a short circuit.
I wouldn't connect it to RST as the reset pin normally has decoupling capacitor as well as a pull up to slow the rise of that signal during power up. Slowing both RESET and EN is almost certainly is fine but is an extra complication I prefer not to introduce.
If not planning to use EN for wake up then it is actually safe to just connect it to the Vdd (3.3V) as it is a pure input. That doesn't apply to the other pins like GPIO15 or GPIO0 where connecting to Vdd or GND carries the risk that the program may configure the pin as an output and then try to drive into a short circuit.
I wouldn't connect it to RST as the reset pin normally has decoupling capacitor as well as a pull up to slow the rise of that signal during power up. Slowing both RESET and EN is almost certainly is fine but is an extra complication I prefer not to introduce.