GPIO 36 Input causes reset

Volvox
Posts: 21
Joined: Sat Mar 18, 2017 7:54 pm

GPIO 36 Input causes reset

Postby Volvox » 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!
Attachments
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Bildschirmfoto 2019-12-05 um 15.10.05.png
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NotMyRealName
Posts: 41
Joined: Thu Feb 13, 2020 1:35 am

Re: GPIO 36 Input causes reset

Postby NotMyRealName » Thu Feb 13, 2020 1:41 am

Did you get to the bottom of this? I'm interested to know in case I use this pin in an upcoming design.

Is R13 actually electrically connected both sides? I only see a green dot on one side. If that pin is floating it could be bad.

bintanghd
Posts: 1
Joined: Mon Jun 24, 2024 12:24 am

Re: GPIO 36 Input causes reset

Postby bintanghd » Mon Jun 24, 2024 12:31 am

any new update on this ?

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