GPIO 36 Input causes reset
Posted: Thu Dec 05, 2019 2:17 pm
Hello together,
I have a strange behaviour on the GPIO36. I use it as input for an external connectable button. It is wired up with a simple schematic with an RC filter and some TVS to protect too high input voltages on this pin. (See attached schematic snippets, the button closes a connection from a pulled up to 3,3V line to GND, that detects the input).
This works as expected on other pins, but on GPIO36 if I press the button initially it also ties the directly adjacent EN pin a bit lower for a short time (no matter how long I hold the button pressed, but at the moment I press there is a short drop in the voltage on the EN pin.
I checked also the complete 3,3V supply that remains stable in this case.
On EN pin there is a 100n/10k RC Filter as recommended.
Now my question:
Any ideas why this EN line is also pulled low? Interesting fact: the longer the wire on the external button is (lets say about 10 to 20m connected), the more the EN line will be dropped to GND, sometimes completely so that the whole ESP performs a reboot ...
Thanks for sharing your ideas!
I have a strange behaviour on the GPIO36. I use it as input for an external connectable button. It is wired up with a simple schematic with an RC filter and some TVS to protect too high input voltages on this pin. (See attached schematic snippets, the button closes a connection from a pulled up to 3,3V line to GND, that detects the input).
This works as expected on other pins, but on GPIO36 if I press the button initially it also ties the directly adjacent EN pin a bit lower for a short time (no matter how long I hold the button pressed, but at the moment I press there is a short drop in the voltage on the EN pin.
I checked also the complete 3,3V supply that remains stable in this case.
On EN pin there is a 100n/10k RC Filter as recommended.
Now my question:
Any ideas why this EN line is also pulled low? Interesting fact: the longer the wire on the external button is (lets say about 10 to 20m connected), the more the EN line will be dropped to GND, sometimes completely so that the whole ESP performs a reboot ...
Thanks for sharing your ideas!