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Touch Sensor (TTP223)

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Overview

• VCC — accepts 2 V to 5.5 V, so the board’s 3.3 V pin powers it directly
• GND — shared ground with the board
• OUT — digital output, HIGH while touched (momentary mode)

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Pin Configuration

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Key Features

• TTP223 capacitive sensing — no moving parts, nothing to wear out
• 2.0–5.5 V supply — runs directly from the GLYPH board’s 3.3 V pin, sips under 60 µA
• Digital output — HIGH while touched (momentary mode), plus an onboard touch LED
• Senses through thin insulators — glass, acrylic or paper up to a few millimetres
• Toggle mode option — the A/B jumper turns the module into a latching switch

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Application

• Touch lamps and light switches
• Wake-up buttons for battery-powered devices
• Interactive controls and toy interfaces
• Replacing mechanical buttons in enclosures
• Hidden controls behind plastic panels

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Step 1: Hardware Required

1. Pcbcupid GLYPH-C6 board
2. TTP223 capacitive touch module
3. 3 × jumper wires (female–female)
4. USB-C cable for power and upload

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Step 2: Circuit Diagram

• VCC → the board’s 3V pin
• GND → the board’s GND
• OUT → GPIO 20
• If the module has an A/B jumper, make sure it is on A (momentary)

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Step 3: Code Setup

// TTP223 capacitive touch sensor on Pcbcupid GLYPH-C6
// Touch the pad: the onboard LED toggles and Serial shows each event.

#define TOUCH_PIN 20  // TTP223 OUT
#define LED_PIN 14    // GLYPH-C6 onboard LED

bool ledOn = false;
int touchCount = 0;

bool lastReading = LOW;   // raw reading from the sensor
bool stableState = LOW;   // debounced state
unsigned long lastDebounceMs = 0;
const unsigned long debounceMs = 50;

void setup() {
  Serial.begin(115200);
  pinMode(TOUCH_PIN, INPUT);
  pinMode(LED_PIN, OUTPUT);
  digitalWrite(LED_PIN, LOW);
  Serial.println("TTP223 touch sensor ready - touch the pad!");
}

void loop() {
  bool reading = digitalRead(TOUCH_PIN);

  // Restart the debounce timer whenever the raw reading changes
  if (reading != lastReading) {
    lastDebounceMs = millis();
  }

  // Only accept a state that has held steady for debounceMs
  if ((millis() - lastDebounceMs) > debounceMs && reading != stableState) {
    stableState = reading;

    if (stableState == HIGH) {
      touchCount++;
      ledOn = !ledOn;
      digitalWrite(LED_PIN, ledOn);
      Serial.print("Touched! (");
      Serial.print(touchCount);
      Serial.println(")");
    } else {
      Serial.println("Released");
    }
  }

  lastReading = reading;
}

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Step 4: Upload the Code

1. Connect the GLYPH-C6 to your computer with the USB-C cable.
2. In the Arduino IDE, go to Tools → Board → esp32 → Pcbcupid GLYPH C6.

3. Set Tools → USB CDC On Boot → Enabled.

4. Select the board’s port under Tools → Port.
5. Click the upload arrow button (or press Ctrl + U) and wait for the upload to finish.

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Step 5: Observe the Output

• The module’s own LED lights up while your finger is on the pad.
• The GLYPH-C6’s onboard LED toggles on and off with every tap.
• The Serial Monitor prints Touched! (1), Released, Touched! (2), and so on.

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Things to Try

• Touch through a cover — hold a sheet of paper or a piece of thin acrylic on the pad and touch that; the sensor still triggers.
• Hold and release — the output stays HIGH the whole time you hold the pad, which is why the “hold” behaviour is different from the “tap” behaviour.
• Go latching — if your module has an A/B jumper, move it to B and touch once: the module’s output now stays HIGH until the next touch, and the sketch only reacts on each state change.

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Troubleshooting

• The board LED does not toggle — check the OUT → GPIO 20 wire, and that the module LED lights when touched.
• The LED toggles on its own — the pad can pick up interference from nearby mains wiring. Power the board from a USB power bank (battery) and see if the false triggers stop.
• The board LED is on when it should be off — your board’s LED may be active-low. Swap the digitalWrite(LED_PIN, ...) HIGH/LOW values.

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Alternative: External LED Touch Lamp

// TTP223 touch lamp: every touch toggles an external LED.
#define TOUCH_PIN 20  // TTP223 OUT
#define LED_PIN 19    // external LED (through 220 ohm resistor)

bool lampOn = false;
bool lastState = LOW;

void setup() {
  Serial.begin(115200);
  pinMode(TOUCH_PIN, INPUT);
  pinMode(LED_PIN, OUTPUT);
  digitalWrite(LED_PIN, LOW);
}

void loop() {
  bool state = digitalRead(TOUCH_PIN);

  // react only on the LOW -> HIGH edge, so one tap = one toggle
  if (state == HIGH && lastState == LOW) {
    lampOn = !lampOn;
    digitalWrite(LED_PIN, lampOn);
    Serial.println(lampOn ? "Lamp ON" : "Lamp OFF");
  }

  lastState = state;
}