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esp32 s2 mini

I have a problem with capacitive sensor. I have created PCB with 2 capacitive sensors. Everything is working fine and ESP32 s2 mini reading values as I expect while I powering up esp32 with type-c 5v, but then I try to power up eps32 with AC-DC 5V 700mA Buck Converter (AC 220v) via "vbus" pin:

ac/dc buck converter

touch sensor values goes crazy. I uploaded picture of PCB with touch sensor and pins which connected to other PCB with esp32 s2 and buck converted. Values reading with "touchRead" function.

pcb design

I have tried to add "filters" and "thresholds" to code, but nothing worked.

I'm very beginner in electronics.

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  • \$\begingroup\$ If you have an oscilloscope try taking a look at your power rail; I have the strong suspicion that your buck converter is putting out some pretty noisy current as it has the symptoms of being an Amazon/Aliexpress/eBay purchase. Otherwise try adding some capacitance across the power terminals where it enters the board. Or possibly a higher quality power supply would fix it. \$\endgroup\$
    – vir
    Commented Feb 8 at 18:02
  • \$\begingroup\$ Is it different if you swap L and N of the AC supply input? \$\endgroup\$
    – Jens
    Commented Feb 9 at 14:45
  • \$\begingroup\$ Connect ESP GND to PE. This has a good chance to get rid of the noise coupled in by the Y-capacitor of the AC/DC converter. \$\endgroup\$
    – Jens
    Commented Feb 9 at 21:16

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