Using touch GPIO with ungrounded AC/DC converter

[ybizeul]

Hi folks,

I couldn't find proper documentation regarding the behavior I'm observing.

Basically, my touch sensor is working just fine when tested with USB power, but if using a AC/DC 5V converter on Vin, readings seem to be erratic.

It seems to me it is caused by the lack of actual ground on the circuit, and I'm wondering how to solve this so I can have a stable reading on touch7 gpio. In fact, the reading goes way down when I touch the ESP32 shield or the USB connector.

What is a proper way to a stable touch GPIO reading when using a DC converter ?

Thanks !

I'm using a ESP31DEVKITV1 with ESPHome firmware

[ybizeul]

I'm still looking for a solution to this. I changed AC/DC converter for this one https://www.banggood.com/fr/5Pcs-AC-DC- ... rehouse=CN with no change in behavior.

What I did though, is try to put a wire between GND and some random ground in the house, I used a plugged-in USB cable connector on the outside metal, and readings are then stabilized.

It really looks like I'm missing some proper grounding but not sure how to achieve this. I could use a grounded plug, but I'd like to understand what is going on.