Tag: LVGL Graphics Library

To add the touch functionality to an ESP32-S3 HMI, it will need to use a combination of the ESP32-S3 microcontroller, a suitable Touch library, and the LVGL  graphics library. Below are the general steps to add these functionalities:

1. Set Up Development Environment:

Install Arduino IDE on PC.

Integrate ESP32 board support in Arduino IDE.

Install required libraries for ESP32, touch, and LVGL. 

The Touch library may need to use a library that is compatible with the specific 5-inch resistive touch.

2. Include Libraries in Arduino Sketch:

Include the required libraries at the beginning of the Arduino sketch:

#include <XPT2046_Touchscreen.h>

#include <lvgl.h>

3. Initialize Touch parameters:

• Initialize the set points

The touch screen set points are configured through an example code provided by a touch library. By executing the code and interacting with the four sides of the display, the corresponding values are displayed in the serial monitor. This process enables the determination of touchscreen set points based on the user’s input and observation of the serial output.

#define TOUCH_MAP_X1 270

 #define TOUCH_MAP_X2 3800

 #define TOUCH_MAP_Y1 3600

 #define TOUCH_MAP_Y2 330

• Variables touch_last_x and touch_last_y store the last touched coordinates.

int touch_last_x = 0, touch_last_y = 0;

#if defined(TOUCH_XPT2046)

XPT2046_Touchscreen ts(TOUCH_XPT2046_CS, TOUCH_XPT2046_INT);

• Touch Initialization Function.

void touch_init() {

#if defined(TOUCH_XPT2046)

  SPI.begin(TOUCH_XPT2046_SCK, TOUCH_XPT2046_MISO, TOUCH_XPT2046_MOSI, TOUCH_XPT2046_CS);

  ts.begin();

  ts.setRotation(TOUCH_XPT2046_ROTATION);

• Check for Touch Signal.

bool touch_has_signal() {

#if defined(TOUCH_XPT2046)

  return ts.tirqTouched();

• Check if Touched

bool touch_touched() {

#if defined(TOUCH_XPT2046)

  if (ts.touched())  {

    TS_Point p = ts.getPoint();

• Check if Touch Released.

bool touch_released(){

if defined(TOUCH_XPT2046)

  return true;

Example

This touch code provides an abstraction layer for the touch library, allowing the user to easily understand. The code includes initialization, event handling, and functions to check if the screen is touched or released. 

If buttonXMin, buttonXMax, buttonYMin, and buttonYMax represent the borders or boundaries of the region on the touch screen corresponding to the position of the button. let’s see how to configure a button, and set its action. 

#include <XPT2046_Touchscreen.h>

#define TOUCH_CS 10 // Example pin for touch CS

XPT2046_Touchscreen ts(TOUCH_CS);

#define BUTTON_PIN 7 // Example pin for the button

void setup() {

  Serial.begin(9600);

  ts.begin();

  pinMode(BUTTON_PIN, INPUT);

}

void loop() {

  // Read touch input

  TS_Point p = ts.getPoint();

  // Check if the touch screen is touched

  if (p.z > MINPRESSURE && p.z < MAXPRESSURE) {

    // Process touch input (e.g., map coordinates, perform actions)

    int mappedX = map(p.x, TS_MINX, TS_MAXX, 0, 800); // Adjust based on display size

    int mappedY = map(p.y, TS_MINY, TS_MAXY, 0, 480); // Adjust based on display size

    Serial.print(“Touched at X: “);

    Serial.print(mappedX);

    Serial.print(“, Y: “);

    Serial.println(mappedY);

    // Check if the touch is in the region of the button

    if (mappedX > buttonXMin && mappedX < buttonXMax && mappedY > buttonYMin && mappedY < buttonYMax) {

      // Button is pressed, perform action

      Serial.println(“Button Pressed!”);

      // Add button action here

    }

  }

}