esp32 capacitive touch sensing pins with arduino ide
Learn how to use ESP32 capacitive touch pins using Arduino IDE. We will explain the working of touch-sensing pins with an example.
Table of Content
Working of touch-sensing GPIOs
ESP32 has 10 capacitive-sensing GPIOs, which detect variations induced by touching or approaching the GPIOs with a finger or other objects. The low-noise nature of the design and the high sensitivity of the circuit allows relatively small pads to be used.
| Capacitive signal name | Pin number |
| T0 | GPIO4 |
| T1 | GPIO0 |
| T2 | GPIO2 |
| T3 | MTDO |
| T4 | MTCK |
| T5 | MTDI |
| T6 | MTMS |
| T7 | GPIO27 |
| T8 | 32K-XN |
| T9 | 32K-XP |
Applications of Capacitive Touch Sensors
- Low-power IoT device that wakes up on touch.
- Touch-activated light control.
- Low-power remote.
- Smart switches in home automation.
- Interactive art installation.
- gesture control systems.
touchRead(GPIO)
the touchread() function in Arduino IDe accepts the GPIO pin as an argument and returns a value. The higher value indicates no touch whereas the lower value suggests a touch.
Code
void setup()
{
Serial.begin(115200);
delay(1000);
}
void loop()
{
Serial.println(touchRead(T0));
delay(100);
}example
const int ledPin = 2;
const int touchPin = T0;
const int touchThresold = 40;
void setup()
{
Serial.begin(115200);
pinMode(ledPin, OUTPUT);
delay(1000);
}
void loop()
{
int touchVal = touchRead(T0));
if (touchValue < touchThresold ){
digitalWrite(ledPin, HIGH); // Turn LED on
}
else{
digitalWrite(ledPin, LOW); // Turn LED off
}
delay(100);
}The code reads the input from the touch-pin T0 (GPIO4) and turns on the Led if the touch is detected.