Input devices

TTP223 touch button with ESP32

A touch pad that works through the wall of a plastic case needs no hole, so nothing leaks in and there is no switch to wear out. The TTP223 module does this for pennies, using one GPIO. The output goes high while you touch it, with no pull-up or debounce needed, since the chip handles that.

Power it from 3V3 on an ESP32. The supply range is 2.0 to 5.5 V, but one manual says the output follows the supply, so a module on 5 V could put 5 V on your pin. Keep it simple and use 3.3 V.

Two solder pads change the behaviour. With both open, it is momentary and active high. One pad switches it to toggle mode, like a latching switch, and the other inverts the output. Sources disagree on which pad is which: most say A sets polarity and B sets toggle, while one manual says the reverse. Bridge one and test with a meter. Do not assume. Sources say it works through thin acrylic, glass or plastic, but they give no thickness limit, so try your actual case. Metal in front of it will not work. Water and a wet finger can trigger it, which is a poor match for outdoor panels. It is also a bad choice for anything with safety impact. LCD Ultra Pro can read a hardware pin as 0 or 1, so a rule can react to a touch without code.

const int TOUCH_PIN = 5;
int last = LOW;

void setup() {
  Serial.begin(115200);
  pinMode(TOUCH_PIN, INPUT);
}

void loop() {
  int now = digitalRead(TOUCH_PIN);
  if (now != last) {
    last = now;
    Serial.println(now ? "Touched" : "Released");
  }
  delay(10);
}

Use this information at your own risk. It is for general guidance only: the example code compiles, but it has not been tested on every part, and modules differ between sellers. Check the manufacturer's data before you build. Product names belong to their owners, and LCD Ultra Pro is not affiliated with them. See our Terms.