Part

Touch sensor, TTP223

A finger on the pad drives SIG high within 60 ms. No pull-up, no bounce.

3 pins
2 settings
In 1 project
In 1 lesson

Drawn live by the editor's own code, at the size you see it.

At a glance

The Touch sensor, TTP223 in brief

What it is, and every setting the properties panel gives it.

The TTP223 module is the small red square with a round pad printed on it, a capacitive touch sensor: a finger adds a few picofarads to the pad, and the chip drives SIG in response. It has three pins, SIG, VCC and GND, and runs from 2.0 to 5.5 volts, so it powers from an Arduino Uno’s 5 volts or straight from an ESP32’s 3.3 volts, keeping SIG safe for its pins. SIG is a push-pull output, so it needs no pull-up and does not bounce. Mokxi follows the Tontek datasheet: a touch takes the full 60 milliseconds to reach SIG and so does a release, so a shorter tap is never seen, and SIG sits at its power-on state for half a second while the chip calibrates. A finger already on the pad when that time ends becomes part of the pad, which is the classic fault of a module that ignores its first touch. The toggle and activelow properties are the B and A solder jumpers on the back, for toggle or active-low output. Sensitivity, slow recalibration and water on the pad are not modeled.

Family: Inputs
Pins: 3
toggle: false
activelow: false

A circuit built around it, running and explained: the Touch sensor simulator.

Pins

3 pins

Named as the editor names them, so a wire lands where you expect it.

Role

What it does

SIG

Output

A push-pull output, HIGH while touched as shipped.

VCC

Input or output

Supply, 2.0 V to 5.5 V.

GND

Input or output

Ground.

How to use it

How to use the TTP223 touch sensor with an Arduino

SIG to a digital pin, VCC to a supply and GND to GND. SIG is a real output, so set the pin to plain INPUT, not INPUT_PULLUP, and it reads HIGH while a finger is on the pad. The climate display here powers the module from the Uno’s 3V3 pin, and its 3.3 V high still reads as HIGH on the 5 V Uno.

To make the pad a switch, act on the rising edge, the moment SIG goes from LOW to HIGH, not on the level; holding a finger there then flips the setting once. Keep fingers off the pad for the first half second after power-up: the chip is calibrating then, and a finger still on the pad when it finishes becomes part of the pad until it lifts off.

Part pin

Board pin

SIG

Pin 2

VCC

3V3

GND

On an ESP32 power it from 3.3 V and read SIG on any GPIO; the ESP32-C3 desk robot reads its pad on GPIO 3.

Arduino Uno: touch climate displaylive0.000 s 0.00x

Hold the button

This is the simulator itself, running here. Click anything to open it in the editor.

Open this project in the editor Read the full tutorial

Flipping on each touch, from the climate display

bool touched = digitalRead(TOUCH) == HIGH;
bool flipped = touched && !wasTouched;
wasTouched = touched;
if (flipped) {
  fahrenheit = !fahrenheit;
}

How it is modeled

What is true about the Touch sensor, TTP223, here

In its help article’s own words: what the simulation gets right, and where it stops.

Modeled

From the Tontek TTP223 datasheet:

Response time. Up to 60 ms in fast mode, which is the only mode the six-pin chip on these modules has. A touch takes 60 ms to reach SIG, and so does a release. A tap shorter than that is never seen.

Power-on calibration. For about half a second after power comes up the chip is measuring the pad and ignores it. A finger already on the pad when that time ends becomes part of the pad: it has to come off and go back on before it counts.

The output. A real push-pull output: 8 mA sink and 4 mA source at 3 V, so it drives a pin or an LED with no pull-up.

No time limit. The module's chip has its maximum-on-time timeout disabled, so SIG stays high for as long as the finger stays.