TTP223 touch sensor with Raspberry Pi Pico W — MicroPython toggle switch

The TTP223 turns a small copper pad into a button with no moving parts. Powered from 3V3, its I/O pin goes HIGH while you touch it, and the Pico W reads it on GP16.

This script uses a pin interrupt so even a quick tap is caught, and toggles the on-board LED on each touch — a touch light switch in a dozen lines.

Wiring

Every connection
Raspberry Pi Pico W	TTP223 capacitive touch module	Wire	Notes
3V3	VCC	red	3V3 is pin 36. I/O swings to VCC, so 3.3 V keeps it Pico-safe.
GND	GND	black
GP16	I/O	yellow	GP16 is physical pin 21.

2.0–5.5 V part, 3.3 V board. 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.

Board quirks

By default I/O is HIGH while touched. Solder pad A changes it to active-LOW; pad B makes the module itself toggle on each touch.
The interrupt handler only counts; the main loop prints and toggles the LED. Keep IRQ handlers this short in MicroPython — no printing or allocating inside them.
The TTP223 calibrates itself at power-up. Don’t touch the pad while you plug in, or it treats your finger as “not touched”.
It works through 1–2 mm of plastic or glass, so you can hide it behind a project box lid.

Code

main.pyMicroPython

# TTP223 capacitive touch button on a Raspberry Pi Pico W (MicroPython).
# Wiring: VCC -> 3V3 (pin 36), GND -> GND, I/O -> GP16 (pin 21).
# Default module setting: I/O goes HIGH while touched. Each touch toggles the on-board LED,
# and an interrupt counts touches without missing short taps.
from machine import Pin
import time

touch = Pin(16, Pin.IN)
led = Pin("LED", Pin.OUT)
touches = 0
last_ms = 0


def on_touch(pin):
    global touches, last_ms
    now = time.ticks_ms()
    if time.ticks_diff(now, last_ms) > 150:  # ignore re-triggers within 150 ms
        touches += 1
        last_ms = now


touch.irq(trigger=Pin.IRQ_RISING, handler=on_touch)

print("TTP223 on GP16 - touch the pad")
seen = 0
while True:
    if touches != seen:
        seen = touches
        led.toggle()
        print("Touch #{}  LED {}".format(seen, "on" if led.value() else "off"))
    time.sleep_ms(20)

# TTP223 capacitive touch button on a Raspberry Pi Pico W (MicroPython).
# Wiring: VCC -> 3V3 (pin 36), GND -> GND, I/O -> GP16 (pin 21).
# Default module setting: I/O goes HIGH while touched. Each touch toggles the on-board LED,
# and an interrupt counts touches without missing short taps.
from machine import Pin
import time

touch = Pin(16, Pin.IN)
led = Pin("LED", Pin.OUT)
touches = 0
last_ms = 0


def on_touch(pin):
    global touches, last_ms
    now = time.ticks_ms()
    if time.ticks_diff(now, last_ms) > 150:  # ignore re-triggers within 150 ms
        touches += 1
        last_ms = now


touch.irq(trigger=Pin.IRQ_RISING, handler=on_touch)

print("TTP223 on GP16 - touch the pad")
seen = 0
while True:
    if touches != seen:
        seen = touches
        led.toggle()
        print("Touch #{}  LED {}".format(seen, "on" if led.value() else "off"))
    time.sleep_ms(20)

Expected serial output

REPL / Thonny shellOutput

TTP223 on GP16 - touch the pad
Touch #1  LED on
Touch #2  LED off
Touch #3  LED on

TTP223 on GP16 - touch the pad
Touch #1  LED on
Touch #2  LED off
Touch #3  LED on

Common errors

LED toggles twice per touch

Pad B is bridged (module toggle mode) or the touch is bouncing. Leave A and B open, and keep the 150 ms lock-out in the handler.

Always touched after power-up

A finger or metal was near the pad while it calibrated. Power-cycle with nothing touching it.