TTP223 capacitive touch module
TTP223 touch sensor module pinout (VCC, I/O, GND), the A and B solder pads for active-LOW and toggle modes, power-on calibration and touching through plastic.
Community draft — report a mistake
3.3 V or 5 V? I/O drives to the supply voltage, so power it from 3.3 V on ESP32 and Pico and from 5 V on Uno. It runs happily at either.
The TTP223 is a one-key capacitive touch controller: the copper pad on the board forms a capacitor with your finger, and the chip notices the change. The I/O pin goes HIGH while you touch — no debouncing or library needed, just digitalRead(). It works through thin plastic or glass, which makes it great for sealed switches in kitchens, bathrooms and outdoor boxes.
Two solder pads on the back set the mode: A bridged makes the output active-LOW, B bridged makes it toggle (touch once on, touch again off). Both open = momentary, active-HIGH (the default).
It calibrates to its surroundings at power-on, so a water drop or a hand on the pad during start-up becomes the new “untouched”. If it behaves oddly after installation, power-cycle it. Avoid long wires on the pad — they add capacitance and false touches.
Prices are indicative (Nov 2026) and vary by seller.
Pinout
| Pin | What it does |
|---|---|
VCC | 2.0–5.5 V supply (a few µA idle) |
I/O | Output — HIGH while touched (default). Pads A and B change this; see below. Printed SIG or OUT on some boards. |
GND | Ground |
Use it with
Common errors
Reads touched all the time, or never
The chip calibrates for about half a second at power-on. Don’t touch the pad (or have metal near it) while powering up, and power-cycle it after mounting it in the enclosure.
Output toggles instead of following the finger
Pad B is bridged (toggle mode). Remove the solder bridge for momentary mode.
Output is LOW when touched
Pad A is bridged (active-LOW). Clear it, or invert the logic in code.
Doesn’t respond through the enclosure
It works through about 2–3 mm of plastic or glass. Press the pad flat against the inside of the wall with no air gap, and use a thinner panel if needed.