TTP223 touch sensor with Arduino Uno — tap, long press and solder pads

The TTP223 is a tiny capacitive touch sensor — the small square board with a round pad that costs about ₹15. Touch the pad, or the plastic in front of it, and its output goes HIGH. It replaces a push button where you want a sealed, splash-proof panel, which is handy in kitchens and bathrooms.

On the Uno it runs from 5V and its I/O pin goes straight to D2. The chip drives its own output, so it needs no pull-up resistor and doesn’t bounce like a mechanical button.

The sketch tells a tap (which toggles the on-board LED) from a long press of one second — two actions from one pad.

Wiring

Board quirks

• The chip calibrates itself in the first half second after power-up. A finger on the pad during that time becomes the new “untouched” level and the pad stops working until the next power cycle.
• Solder pad A makes the output active-LOW; pad B makes it toggle on each touch. With pad A bridged, change the sketch to look for LOW.
• It senses through 1–3 mm of plastic or glass, so you can hide it behind an enclosure wall with no hole. Stick it flat and tight — an air gap kills the sensitivity.
• No pull-up is needed: the TTP223 drives its output actively, both HIGH and LOW.

Code

// TTP223 capacitive touch module on an Arduino Uno R3.
// VCC → 5V, I/O → D2, GND → GND. Default pads: I/O is HIGH while touched.
// Tap = toggle the on-board "L" LED, hold 1 s = long press.
const uint8_t TOUCH_PIN = 2;

bool ledOn = false;
bool lastTouch = false;
bool longSent = false;
unsigned long touchStart = 0;

void setup() {
  pinMode(TOUCH_PIN, INPUT);
  pinMode(LED_BUILTIN, OUTPUT);
  Serial.begin(9600);
  Serial.println(F("TTP223 on D2 - tap or hold (don't touch it during power-up)"));
}

void loop() {
  bool touch = digitalRead(TOUCH_PIN) == HIGH;
  if (touch && !lastTouch) {
    touchStart = millis();
    longSent = false;
  }
  if (touch && !longSent && millis() - touchStart > 1000) {
    longSent = true;
    Serial.println(F("Long press"));
  }
  if (!touch && lastTouch && !longSent) {
    ledOn = !ledOn;
    digitalWrite(LED_BUILTIN, ledOn);
    Serial.println(ledOn ? F("Tap - LED on") : F("Tap - LED off"));
  }
  lastTouch = touch;
  delay(10);
}

// TTP223 capacitive touch module on an Arduino Uno R3.
// VCC → 5V, I/O → D2, GND → GND. Default pads: I/O is HIGH while touched.
// Tap = toggle the on-board "L" LED, hold 1 s = long press.
const uint8_t TOUCH_PIN = 2;

bool ledOn = false;
bool lastTouch = false;
bool longSent = false;
unsigned long touchStart = 0;

void setup() {
  pinMode(TOUCH_PIN, INPUT);
  pinMode(LED_BUILTIN, OUTPUT);
  Serial.begin(9600);
  Serial.println(F("TTP223 on D2 - tap or hold (don't touch it during power-up)"));
}

void loop() {
  bool touch = digitalRead(TOUCH_PIN) == HIGH;
  if (touch && !lastTouch) {
    touchStart = millis();
    longSent = false;
  }
  if (touch && !longSent && millis() - touchStart > 1000) {
    longSent = true;
    Serial.println(F("Long press"));
  }
  if (!touch && lastTouch && !longSent) {
    ledOn = !ledOn;
    digitalWrite(LED_BUILTIN, ledOn);
    Serial.println(ledOn ? F("Tap - LED on") : F("Tap - LED off"));
  }
  lastTouch = touch;
  delay(10);
}

Expected serial output

TTP223 on D2 - tap or hold (don't touch it during power-up)
Tap - LED on
Tap - LED off
Long press

TTP223 on D2 - tap or hold (don't touch it during power-up)
Tap - LED on
Tap - LED off
Long press

Common errors