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I am trying to use the Touch sensitive pins of a ESP32. Problem is that between the ESP32 and the actual touch pads there is 1 meter of wire. without the cable attached the value is > 200, but as soon as I connect the cable the value drops to about 20. Then when I touch the pad it drops to about 7/8. The problem is that this is very unstable and from time to time it triggers alone, probably picking up something over the wires?

Is there a way to use the touch sensitive pins without being at 5 cm from the esp?

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    \$\begingroup\$ ESP32s are really small. Why don't you move the ESp32 out where where you need your touch control and run whatever other connections you need back to the 1m away point? \$\endgroup\$
    – jwh20
    Commented Jul 14, 2021 at 13:19
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    \$\begingroup\$ Exactly what kind of wire do you have between the touch sensor and the ESP? \$\endgroup\$
    – Elliot Alderson
    Commented Jul 14, 2021 at 13:39

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To detect a touch with say 0 to 100 pF, the sensor threshold must be adjusted as close as possible to the off threshold without false EMI triggers.

When line noise interferes with the applied LF signal it is because the sensor is converting a common mode field into a differential voltage when the signal impedance is much greater than the stray return path to 0V or unbalanced. This can be balanced or shielded or both but this adds shunt capacitance so more immune but smaller changes require a tighter threshold.

Without details on the signal view when it works and fails with a layout and photo of all aspects of the sensor to ESP32 and it’s power connections, it’s all I can say.

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