ESP32 TOUCH SENSOR

MOHAMMAD SAIFIQUL AIMAN B MOHAMMAD ALI

192011145

R2427-MICROELECTRONIC ENGINEERING

There are ten capacitive touch GPIOs on the ESP32. These GPIOs can detect changes in anything that has an electrical charge, such as the skin. As a result, they may detect fluctuations caused by a finger touching the GPIOs. These pins may easily be incorporated into capacitive pads and can be used to replace mechanical buttons.

Here’s a list of parts you need to assemble the circuit

 ESP32 DOIT DEVKIT V1 Board

 5mm LED 

330 Ohm resistor 

Breadboard 

Jumper wires

touchRead() 

Reading the touch sensor is straightforward. In the Arduino IDE, you use the touchRead() function, that accepts as argument, the GPIO you want to read. 

Assemble the circuit shown below

Copy the source code below

Source code :

// set pin numbers

const int touchPin = 4;

const int ledPin = 16;

// change with your threshold value

const int threshold = 20;

// variable for storing the touch pin value 

int touchValue;

void setup(){

Serial.begin(115200);

delay(1000); // give me time to bring up serial monitor

// initialize the LED pin as an output:

pinMode (ledPin, OUTPUT);

}

void loop(){

// read the state of the pushbutton value:

touchValue = touchRead(touchPin);

Serial.print(touchValue);

// check if the touchValue is below the threshold

// if it is, set ledPin to HIGH

if(touchValue < threshold){

 // turn LED on

 digitalWrite(ledPin, HIGH);

 Serial.println(" - LED on");

}

else{

 // turn LED off

 digitalWrite(ledPin, LOW);

 Serial.println(" - LED off");

}

delay(500);

}

Uploading the Sketch :

Before clicking the upload button, go to Tools  Board, and select the board you’re using. In my case. It’s the DOIT ESP32 DEVKIT V1 board. Also don’t forget to select your ESP32’s COM port.

Now, press the upload button.

Then, wait for the “Done uploading.” message: 

Testing the example :

Connect a jumper wire to GPIO 4. You will touch the metal part of this wire so that it senses the touch. In the Arduino IDE window, go to Tools and open the Serial Monitor at a baud rate of 115200. You’ll see the new values being displayed every second. Touch the wire connected to GPIO 4 and you’ll see the values decreasing.

You can also use the serial plotter to better see the values. Close the serial monitor, go to Tools > SerialPlotter

Testing your project :

When touching the jumper wire, LED will blink.