ESP32 CYD with LVGL: Weather Station (Description, Temperature, Humidity)

In this project, you’ll learn how to turn your ESP32 Cheap Yellow Display (CYD) board into a weather station that displays weather description, temperature, humidity, and date using LVGL (Light Versatile Graphics Library). We’ll use the Open-Meteo API to get the weather data and the ESP32 chip will be programmed using Arduino IDE.

New to the ESP32 Cheap Yellow Display? Start here: Getting Started with ESP32 Cheap Yellow Display Board – CYD (ESP32-2432S028R).

Project Overview

We’ll display the current weather description, temperature, humidity, and date on the ESP32 CYD board. The weather description will also be identified with an image.

To get an accurate weather description for your location, we’ll use the free Open-Meteo API. To get the data from the API, the ESP32 needs to connect to the internet, so you need to have a router in your surroundings so that the ESP32 can connect to it.

Prerequisites

Before proceeding, make sure you follow the next prerequisites. You must follow all steps, otherwise, your project will not work.

1) Parts Required

For this project, you need the following parts

• ESP32-2432S028R – 2.8 inch 240×320 Smart Display TFT with Touchscreen

2) Install ESP32 Boards in Arduino IDE

We’ll program the ESP32 using Arduino IDE. Make sure you have the ESP32 boards installed. Follow the next tutorial:

• Installing ESP32 Board in Arduino IDE 2 (Windows, Mac OS X, Linux)

3) Get familiar with the ESP32 Cheap Yellow Display

The ESP32-2432S028R development board has become known in the maker community as the “Cheap Yellow Display” or CYD for short. This development board, whose main chip is an ESP32-WROOM-32 module, comes with a 2.8-inch TFT touchscreen LCD, a microSD card interface, an RGB LED, and all the required circuitry to program and apply power to the board.

If this is your first time using the ESP32 Cheap Yellow Display, make sure to follow our getting started guide:

• Getting Started with ESP32 Cheap Yellow Display Board and LVGL

4) Install TFT and LVGL Libraries

LVGL (Light and Versatile Graphics Library) is a free and open-source graphics library that provides a wide range of easy-to-use graphical elements for your microcontroller projects that require a graphical user interface (GUI).

Follow the next tutorial to install and configure the required libraries to use LVGL for the ESP32 Cheap Yellow Display using Arduino IDE.

• Get started with LVGL using the ESP32 Cheap Yellow Display Board (ESP32-2432S028R)

5) Install ArduinoJson Library

For this project, you need to install the ArduinoJSON library to handle the JSON response when you make a request to the WorldTimeAPI.

In the Arduino IDE, go to Sketch > Include Library > Manage Libraries. Search for ArduinoJSON and install the library by Benoit Blanchon. We’re using version 7.0.4. We recommend using the same version.

ESP32 CYD Weather Station – weather_images.h file

To load custom images using LVGL, you need to create an extra file called weather_images.h that must be placed inside the sketch folder. We already prepared that file for you. In order to load the custom images for this weather station project, you need to download the next file.

• Click here to download the weather_images.h file

Important: the weather_images.h file should be placed next to the .ino file in the sketch folder of your project.

Your Arduino IDE should have two tabs:

If you want to learn more about loading images using LVGL, we recommend reading our Guide ESP32 CYD with LVGL: Display Image on the Screen

ESP32 CYD Weather Station – Arduino Code

The following code will create some text labels with the weather description, temperature, humidity, current date, and last updated time. It will also load an image to illustrate the current weather description.

Before uploading the code to your board, you need to insert your network credentials so that the ESP32 can connect to the internet to get the time and date. You also need to insert your latitude, longitude, location, and timezone.

/*  Rui Santos & Sara Santos - Random Nerd Tutorials - https://RandomNerdTutorials.com/esp32-cyd-lvgl-weather-station/
    THIS EXAMPLE WAS TESTED WITH THE FOLLOWING HARDWARE:
    1) ESP32-2432S028R 2.8 inch 240×320 also known as the Cheap Yellow Display (CYD): https://makeradvisor.com/tools/cyd-cheap-yellow-display-esp32-2432s028r/
      SET UP INSTRUCTIONS: https://RandomNerdTutorials.com/cyd-lvgl/
    2) REGULAR ESP32 Dev Board + 2.8 inch 240x320 TFT Display: https://makeradvisor.com/tools/2-8-inch-ili9341-tft-240x320/ and https://makeradvisor.com/tools/esp32-dev-board-wi-fi-bluetooth/
      SET UP INSTRUCTIONS: https://RandomNerdTutorials.com/esp32-tft-lvgl/
    Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files.
    The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
*/

/*  Install the "lvgl" library version 9.X by kisvegabor to interface with the TFT Display - https://lvgl.io/
    *** IMPORTANT: lv_conf.h available on the internet will probably NOT work with the examples available at Random Nerd Tutorials ***
    *** YOU MUST USE THE lv_conf.h FILE PROVIDED IN THE LINK BELOW IN ORDER TO USE THE EXAMPLES FROM RANDOM NERD TUTORIALS ***
    FULL INSTRUCTIONS AVAILABLE ON HOW CONFIGURE THE LIBRARY: https://RandomNerdTutorials.com/cyd-lvgl/ or https://RandomNerdTutorials.com/esp32-tft-lvgl/   */
#include <lvgl.h>

/*  Install the "TFT_eSPI" library by Bodmer to interface with the TFT Display - https://github.com/Bodmer/TFT_eSPI
    *** IMPORTANT: User_Setup.h available on the internet will probably NOT work with the examples available at Random Nerd Tutorials ***
    *** YOU MUST USE THE User_Setup.h FILE PROVIDED IN THE LINK BELOW IN ORDER TO USE THE EXAMPLES FROM RANDOM NERD TUTORIALS ***
    FULL INSTRUCTIONS AVAILABLE ON HOW CONFIGURE THE LIBRARY: https://RandomNerdTutorials.com/cyd-lvgl/ or https://RandomNerdTutorials.com/esp32-tft-lvgl/   */
#include <TFT_eSPI.h>

#include "weather_images.h"
#include <WiFi.h>
#include <HTTPClient.h>
#include <ArduinoJson.h>

// Replace with your network credentials
const char* ssid = "REPLACE_WITH_YOUR_SSID";
const char* password = "REPLACE_WITH_YOUR_PASSWORD";

// Replace with the latitude and longitude to where you want to get the weather
String latitude = "41.14961";
String longitude = "-8.61099";
// Enter your location
String location = "Porto";
// Type the timezone you want to get the time for
String timezone = "Europe/Lisbon";

// Store date and time
String current_date;
String last_weather_update;
String temperature;
String humidity;
int is_day;
int weather_code = 0;
String weather_description;

// SET VARIABLE TO 0 FOR TEMPERATURE IN FAHRENHEIT DEGREES
#define TEMP_CELSIUS 1

#if TEMP_CELSIUS
  String temperature_unit = "";
  const char degree_symbol[] = "\u00B0C";
#else
  String temperature_unit = "&temperature_unit=fahrenheit";
  const char degree_symbol[] = "\u00B0F";
#endif

#define SCREEN_WIDTH 240
#define SCREEN_HEIGHT 320

#define DRAW_BUF_SIZE (SCREEN_WIDTH * SCREEN_HEIGHT / 10 * (LV_COLOR_DEPTH / 8))
uint32_t draw_buf[DRAW_BUF_SIZE / 4];

// If logging is enabled, it will inform the user about what is happening in the library
void log_print(lv_log_level_t level, const char * buf) {
  LV_UNUSED(level);
  Serial.println(buf);
  Serial.flush();
}

static lv_obj_t * weather_image;
static lv_obj_t * text_label_date;
static lv_obj_t * text_label_temperature;
static lv_obj_t * text_label_humidity;
static lv_obj_t * text_label_weather_description;
static lv_obj_t * text_label_time_location;

static void timer_cb(lv_timer_t * timer){
  LV_UNUSED(timer);
  get_weather_data();
  get_weather_description(weather_code);
  lv_label_set_text(text_label_date, current_date.c_str());
  lv_label_set_text(text_label_temperature, String("      " + temperature + degree_symbol).c_str());
  lv_label_set_text(text_label_humidity, String("   " + humidity + "%").c_str());
  lv_label_set_text(text_label_weather_description, weather_description.c_str());
  lv_label_set_text(text_label_time_location, String("Last Update: " + last_weather_update + "  |  " + location).c_str());
}

void lv_create_main_gui(void) {
  LV_IMAGE_DECLARE(image_weather_sun);
  LV_IMAGE_DECLARE(image_weather_cloud);
  LV_IMAGE_DECLARE(image_weather_rain);
  LV_IMAGE_DECLARE(image_weather_thunder);
  LV_IMAGE_DECLARE(image_weather_snow);
  LV_IMAGE_DECLARE(image_weather_night);
  LV_IMAGE_DECLARE(image_weather_temperature);
  LV_IMAGE_DECLARE(image_weather_humidity);

  // Get the weather data from open-meteo.com API
  get_weather_data();

  weather_image = lv_image_create(lv_screen_active());
  lv_obj_align(weather_image, LV_ALIGN_CENTER, -80, -20);
  
  get_weather_description(weather_code);

  text_label_date = lv_label_create(lv_screen_active());
  lv_label_set_text(text_label_date, current_date.c_str());
  lv_obj_align(text_label_date, LV_ALIGN_CENTER, 70, -70);
  lv_obj_set_style_text_font((lv_obj_t*) text_label_date, &lv_font_montserrat_26, 0);
  lv_obj_set_style_text_color((lv_obj_t*) text_label_date, lv_palette_main(LV_PALETTE_TEAL), 0);

  lv_obj_t * weather_image_temperature = lv_image_create(lv_screen_active());
  lv_image_set_src(weather_image_temperature, &image_weather_temperature);
  lv_obj_align(weather_image_temperature, LV_ALIGN_CENTER, 30, -25);
  text_label_temperature = lv_label_create(lv_screen_active());
  lv_label_set_text(text_label_temperature, String("      " + temperature + degree_symbol).c_str());
  lv_obj_align(text_label_temperature, LV_ALIGN_CENTER, 70, -25);
  lv_obj_set_style_text_font((lv_obj_t*) text_label_temperature, &lv_font_montserrat_22, 0);

  lv_obj_t * weather_image_humidity = lv_image_create(lv_screen_active());
  lv_image_set_src(weather_image_humidity, &image_weather_humidity);
  lv_obj_align(weather_image_humidity, LV_ALIGN_CENTER, 30, 20);
  text_label_humidity = lv_label_create(lv_screen_active());
  lv_label_set_text(text_label_humidity, String("   " + humidity + "%").c_str());
  lv_obj_align(text_label_humidity, LV_ALIGN_CENTER, 70, 20);
  lv_obj_set_style_text_font((lv_obj_t*) text_label_humidity, &lv_font_montserrat_22, 0);

  text_label_weather_description = lv_label_create(lv_screen_active());
  lv_label_set_text(text_label_weather_description, weather_description.c_str());
  lv_obj_align(text_label_weather_description, LV_ALIGN_BOTTOM_MID, 0, -40);
  lv_obj_set_style_text_font((lv_obj_t*) text_label_weather_description, &lv_font_montserrat_18, 0);

  // Create a text label for the time and timezone aligned center in the bottom of the screen
  text_label_time_location = lv_label_create(lv_screen_active());
  lv_label_set_text(text_label_time_location, String("Last Update: " + last_weather_update + "  |  " + location).c_str());
  lv_obj_align(text_label_time_location, LV_ALIGN_BOTTOM_MID, 0, -10);
  lv_obj_set_style_text_font((lv_obj_t*) text_label_time_location, &lv_font_montserrat_12, 0);
  lv_obj_set_style_text_color((lv_obj_t*) text_label_time_location, lv_palette_main(LV_PALETTE_GREY), 0);

  lv_timer_t * timer = lv_timer_create(timer_cb, 600000, NULL);
  lv_timer_ready(timer);
}

/*
  WMO Weather interpretation codes (WW)- Code	Description
  0	Clear sky
  1, 2, 3	Mainly clear, partly cloudy, and overcast
  45, 48	Fog and depositing rime fog
  51, 53, 55	Drizzle: Light, moderate, and dense intensity
  56, 57	Freezing Drizzle: Light and dense intensity
  61, 63, 65	Rain: Slight, moderate and heavy intensity
  66, 67	Freezing Rain: Light and heavy intensity
  71, 73, 75	Snow fall: Slight, moderate, and heavy intensity
  77	Snow grains
  80, 81, 82	Rain showers: Slight, moderate, and violent
  85, 86	Snow showers slight and heavy
  95 *	Thunderstorm: Slight or moderate
  96, 99 *	Thunderstorm with slight and heavy hail
*/
void get_weather_description(int code) {
  switch (code) {
    case 0:
      if(is_day==1) { lv_image_set_src(weather_image, &image_weather_sun); }
      else { lv_image_set_src(weather_image, &image_weather_night); }
      weather_description = "CLEAR SKY";
      break;
    case 1: 
      if(is_day==1) { lv_image_set_src(weather_image, &image_weather_sun); }
      else { lv_image_set_src(weather_image, &image_weather_night); }
      weather_description = "MAINLY CLEAR";
      break;
    case 2: 
      lv_image_set_src(weather_image, &image_weather_cloud);
      weather_description = "PARTLY CLOUDY";
      break;
    case 3:
      lv_image_set_src(weather_image, &image_weather_cloud);
      weather_description = "OVERCAST";
      break;
    case 45:
      lv_image_set_src(weather_image, &image_weather_cloud);
      weather_description = "FOG";
      break;
    case 48:
      lv_image_set_src(weather_image, &image_weather_cloud);
      weather_description = "DEPOSITING RIME FOG";
      break;
    case 51:
      lv_image_set_src(weather_image, &image_weather_rain);
      weather_description = "DRIZZLE LIGHT INTENSITY";
      break;
    case 53:
      lv_image_set_src(weather_image, &image_weather_rain);
      weather_description = "DRIZZLE MODERATE INTENSITY";
      break;
    case 55:
      lv_image_set_src(weather_image, &image_weather_rain); 
      weather_description = "DRIZZLE DENSE INTENSITY";
      break;
    case 56:
      lv_image_set_src(weather_image, &image_weather_rain);
      weather_description = "FREEZING DRIZZLE LIGHT";
      break;
    case 57:
      lv_image_set_src(weather_image, &image_weather_rain);
      weather_description = "FREEZING DRIZZLE DENSE";
      break;
    case 61:
      lv_image_set_src(weather_image, &image_weather_rain);
      weather_description = "RAIN SLIGHT INTENSITY";
      break;
    case 63:
      lv_image_set_src(weather_image, &image_weather_rain);
      weather_description = "RAIN MODERATE INTENSITY";
      break;
    case 65:
      lv_image_set_src(weather_image, &image_weather_rain);
      weather_description = "RAIN HEAVY INTENSITY";
      break;
    case 66:
      lv_image_set_src(weather_image, &image_weather_rain);
      weather_description = "FREEZING RAIN LIGHT INTENSITY";
      break;
    case 67:
      lv_image_set_src(weather_image, &image_weather_rain);
      weather_description = "FREEZING RAIN HEAVY INTENSITY";
      break;
    case 71:
      lv_image_set_src(weather_image, &image_weather_snow);
      weather_description = "SNOW FALL SLIGHT INTENSITY";
      break;
    case 73:
      lv_image_set_src(weather_image, &image_weather_snow);
      weather_description = "SNOW FALL MODERATE INTENSITY";
      break;
    case 75:
      lv_image_set_src(weather_image, &image_weather_snow);
      weather_description = "SNOW FALL HEAVY INTENSITY";
      break;
    case 77:
      lv_image_set_src(weather_image, &image_weather_snow);
      weather_description = "SNOW GRAINS";
      break;
    case 80:
      lv_image_set_src(weather_image, &image_weather_rain);
      weather_description = "RAIN SHOWERS SLIGHT";
      break;
    case 81:
      lv_image_set_src(weather_image, &image_weather_rain);
      weather_description = "RAIN SHOWERS MODERATE";
      break;
    case 82:
      lv_image_set_src(weather_image, &image_weather_rain);
      weather_description = "RAIN SHOWERS VIOLENT";
      break;
    case 85:
      lv_image_set_src(weather_image, &image_weather_snow);
      weather_description = "SNOW SHOWERS SLIGHT";
      break;
    case 86:
      lv_image_set_src(weather_image, &image_weather_snow);
      weather_description = "SNOW SHOWERS HEAVY";
      break;
    case 95:
      lv_image_set_src(weather_image, &image_weather_thunder);
      weather_description = "THUNDERSTORM";
      break;
    case 96:
      lv_image_set_src(weather_image, &image_weather_thunder);
      weather_description = "THUNDERSTORM SLIGHT HAIL";
      break;
    case 99:
      lv_image_set_src(weather_image, &image_weather_thunder);
      weather_description = "THUNDERSTORM HEAVY HAIL";
      break;
    default: 
      weather_description = "UNKNOWN WEATHER CODE";
      break;
  }
}

void get_weather_data() {
  if (WiFi.status() == WL_CONNECTED) {
    HTTPClient http;
    // Construct the API endpoint
    String url = String("http://api.open-meteo.com/v1/forecast?latitude=" + latitude + "&longitude=" + longitude + "&current=temperature_2m,relative_humidity_2m,is_day,precipitation,rain,weather_code" + temperature_unit + "&timezone=" + timezone + "&forecast_days=1");
    http.begin(url);
    int httpCode = http.GET(); // Make the GET request

    if (httpCode > 0) {
      // Check for the response
      if (httpCode == HTTP_CODE_OK) {
        String payload = http.getString();
        //Serial.println("Request information:");
        //Serial.println(payload);
        // Parse the JSON to extract the time
        StaticJsonDocument<1024> doc;
        DeserializationError error = deserializeJson(doc, payload);
        if (!error) {
          const char* datetime = doc["current"]["time"];
          temperature = String(doc["current"]["temperature_2m"]);
          humidity = String(doc["current"]["relative_humidity_2m"]);
          is_day = String(doc["current"]["is_day"]).toInt();
          weather_code = String(doc["current"]["weather_code"]).toInt();
          /*Serial.println(temperature);
          Serial.println(humidity);
          Serial.println(is_day);
          Serial.println(weather_code);
          Serial.println(String(timezone));*/
          // Split the datetime into date and time
          String datetime_str = String(datetime);
          int splitIndex = datetime_str.indexOf('T');
          current_date = datetime_str.substring(0, splitIndex);
          last_weather_update = datetime_str.substring(splitIndex + 1, splitIndex + 9); // Extract time portion
        } else {
          Serial.print("deserializeJson() failed: ");
          Serial.println(error.c_str());
        }
      }
    } else {
      Serial.printf("GET request failed, error: %s\n", http.errorToString(httpCode).c_str());
    }
    http.end(); // Close connection
  } else {
    Serial.println("Not connected to Wi-Fi");
  }
}

void setup() {
  String LVGL_Arduino = String("LVGL Library Version: ") + lv_version_major() + "." + lv_version_minor() + "." + lv_version_patch();
  Serial.begin(115200);
  Serial.println(LVGL_Arduino);

  // Connect to Wi-Fi
  WiFi.begin(ssid, password);
  Serial.print("Connecting");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.print("\nConnected to Wi-Fi network with IP Address: ");
  Serial.println(WiFi.localIP());
  
  // Start LVGL
  lv_init();
  // Register print function for debugging
  lv_log_register_print_cb(log_print);

  // Create a display object
  lv_display_t * disp;
  // Initialize the TFT display using the TFT_eSPI library
  disp = lv_tft_espi_create(SCREEN_WIDTH, SCREEN_HEIGHT, draw_buf, sizeof(draw_buf));
  lv_display_set_rotation(disp, LV_DISPLAY_ROTATION_270);
  
  // Function to draw the GUI
  lv_create_main_gui();
}

void loop() {
  lv_task_handler();  // let the GUI do its work
  lv_tick_inc(5);     // tell LVGL how much time has passed
  delay(5);           // let this time pass
}

View raw code

How Does the Code Work?

Let’s take a look at how to get current weather data from the API and update the screen with the current values. Alternatively, you can skip to the Demonstration section.

Including Libraries and Images

You need to include the lvgl.h and the TFT_eSPI.h libraries to draw the GUI on the screen.

#include <lvgl.h>
#include <TFT_eSPI.h>

You need to include the WiFi, HTTPClient, and the ArduinoJson libraries to make HTTP requests and handle JSON data.

#include <WiFi.h>
#include <HTTPClient.h>
#include <ArduinoJson.h>

Include the weather_images.h file that contains all the data to draw the weather images.

#include "weather_images.h"

Insert Your Details

In the following lines, you must insert your network credentials so that the ESP32 can connect to your router.

const char* ssid = "REPLACE_WITH_YOUR_SSID";
const char* password = "REPLACE_WITH_YOUR_PASSWORD";

Set your latitude, longitude and location in these three variables:

String latitude = "";
String longitude = "";
String location = "";    // Example: Porto

Set your timezone in the timezone variable at the beginning of the code (list of all available timezones).

const char* timezone = "REPLACE_WITH_YOUR_TIMEZONE";    // Example: Europe/Lisbon

Declaring Other Variables

Create some auxiliary variables to hold the weather data and other values.

String current_date;
String last_weather_update;
String temperature;
String humidity;
int is_day;
int weather_code = 0;
String weather_description;

Temperature in Celsius or Fahrenheit

By default, we’ll display the temperature values in Celsius degrees. If you want to display the temperature readings in Fahrenheit degrees, change TEMP_CELSIUS variable to 0.

// SET VARIABLE TO 0 FOR TEMPERATURE IN FAHRENHEIT DEGREES
#define TEMP_CELSIUS 1

#if TEMP_CELSIUS
  String temperature_unit = "";
  const char degree_symbol[] = "\u00B0C";
#else
  String temperature_unit = "&temperature_unit=fahrenheit";
  const char degree_symbol[] = "\u00B0F";
#endif

Global LVGL Objects

We create some global LVGL objects, so that we can access them inside all functions later on.

static lv_obj_t * weather_image;
static lv_obj_t * text_label_date;
static lv_obj_t * text_label_temperature;
static lv_obj_t * text_label_humidity;
static lv_obj_t * text_label_weather_description;
static lv_obj_t * text_label_time_location;

setup()

In the setup(), include the following lines for debugging. These will print the version of LVGL that you’re using. You must be using version 9.

String LVGL_Arduino = String("LVGL Library Version: ") + lv_version_major() + "." + lv_version_minor() + "." + lv_version_patch();
Serial.begin(115200);
Serial.println(LVGL_Arduino);

Connect to the Internet

To connect the ESP32 to the internet we use the following code.

// Connect to Wi-Fi
WiFi.begin(ssid, password);
Serial.print("Connecting");
while (WiFi.status() != WL_CONNECTED) {
  delay(500);
  Serial.print(".");
}
Serial.print("\nConnected to Wi-Fi network with IP Address: ");
Serial.println(WiFi.localIP());

Initialize the LVGL Library

Initialize the LVGL Library by calling the lv_init() function in the setup().

// Start LVGL
lv_init();

Register Debugging Function

Register your log_print() function declared previously as a function associated with debugging LVGL.

// Register print function for debugging
lv_log_register_print_cb(log_print);

Create a Display Object

To write to the display, you must create a display object first. You need to do this in all your LVGL sketches. The following lines will create an LVGL display object called disp with the screen width, screen height, and drawing buffer defined earlier.

// Create a display object
lv_display_t * disp;
// Initialize the TFT display using the TFT_eSPI library
disp = lv_tft_espi_create(SCREEN_WIDTH, SCREEN_HEIGHT, draw_buf, sizeof(draw_buf));
lv_display_set_rotation(disp, LV_DISPLAY_ROTATION_270);

Drawing the GUI

The LVGL library works asynchronously. You must call the function to draw on the display in the setup(). Then, everything works with events and callbacks. The code will always be listening for events in the background. When something happens, it will run the callback function associated with the event. You don’t need to check for any events in the loop().

Throughout most of our examples, the function that will draw to the screen will be called lv_create_main_gui(). Then, inside that function, we’ll add the instructions to build the interface.

// Function to draw the GUI
lv_create_main_gui();

get_weather_data()

When we initialize the screen, we call the get_weather_data() function to get the latest weather data from the Open-Meteo API. Then, we store the values in some auxiliary variables that will be used to display them on the screen.

void get_weather_data() {
  if (WiFi.status() == WL_CONNECTED) {
    HTTPClient http;
    // Construct the API endpoint
    String url = String("http://api.open-meteo.com/v1/forecast?latitude=" + latitude + "&longitude=" + longitude + "&current=temperature_2m,relative_humidity_2m,is_day,precipitation,rain,weather_code" + temperature_unit + "&timezone=" + timezone + "&forecast_days=1");
    http.begin(url);
    int httpCode = http.GET(); // Make the GET request

    if (httpCode > 0) {
      // Check for the response
      if (httpCode == HTTP_CODE_OK) {
        String payload = http.getString();
        //Serial.println("Request information:");
        //Serial.println(payload);
        // Parse the JSON to extract the time
        StaticJsonDocument<1024> doc;
        DeserializationError error = deserializeJson(doc, payload);
        if (!error) {
          const char* datetime = doc["current"]["time"];
          temperature = String(doc["current"]["temperature_2m"]);
          humidity = String(doc["current"]["relative_humidity_2m"]);
          is_day = String(doc["current"]["is_day"]).toInt();
          weather_code = String(doc["current"]["weather_code"]).toInt();
          // Split the datetime into date and time
          String datetime_str = String(datetime);
          int splitIndex = datetime_str.indexOf('T');
          current_date = datetime_str.substring(0, splitIndex);
          last_weather_update = datetime_str.substring(splitIndex + 1, splitIndex + 9); // Extract time portion
        } else {
          Serial.print("deserializeJson() failed: ");
          Serial.println(error.c_str());
        }
      }
    } else {
      Serial.printf("GET request failed, error: %s\n", http.errorToString(httpCode).c_str());
    }
    http.end(); // Close connection
  } else {
    Serial.println("Not connected to Wi-Fi");
  }
}

get_weather_description(int code)

The get_weather_description() function receives the weather code from the Open-Meteo API and it assigns the correct weather description and corresponding image to illustrate the current weather.

void get_weather_description(int code) {
  switch (code) {
    case 0:
      if(is_day==1) { lv_image_set_src(weather_image, &image_weather_sun); }
      else { lv_image_set_src(weather_image, &image_weather_night); }
      weather_description = "CLEAR SKY";
      break;
    case 1: 
      if(is_day==1) { lv_image_set_src(weather_image, &image_weather_sun); }
      else { lv_image_set_src(weather_image, &image_weather_night); }
      weather_description = "MAINLY CLEAR";
      break;
    case 2: 
      lv_image_set_src(weather_image, &image_weather_cloud);
      weather_description = "PARTLY CLOUDY";
      break;
    case 3:
      lv_image_set_src(weather_image, &image_weather_cloud);
      weather_description = "OVERCAST";
      break;

(...)

Preparing the GUI

Before drawing the main GUI, we start by declaring all the images to illustrate the weather description.

void lv_create_main_gui(void) {
  LV_IMAGE_DECLARE(image_weather_sun);
  LV_IMAGE_DECLARE(image_weather_cloud);
  LV_IMAGE_DECLARE(image_weather_rain);
  LV_IMAGE_DECLARE(image_weather_thunder);
  LV_IMAGE_DECLARE(image_weather_snow);
  LV_IMAGE_DECLARE(image_weather_night);
  LV_IMAGE_DECLARE(image_weather_temperature);
  LV_IMAGE_DECLARE(image_weather_humidity);
(...)

Get the latest weather data

Then, we call the weather API to get the latest data and store the values in the auxiliary variables.

get_weather_data();

Load the weather image

We create an image and set it to the left side of the display.

weather_image = lv_image_create(lv_screen_active());
lv_obj_align(weather_image, LV_ALIGN_CENTER, -80, -20);
  
get_weather_description(weather_code);

Text Labels

To create a text label, we can call the LVGL function lv_label_create() and pass as argument where we want to display the text. We want to add it to the current screen (lv_screen_active()).

text_label_date = lv_label_create(lv_screen_active());

After creating the text label, we can set its text by using the lv_label_set_text() function that accepts as arguments the text label we’re referring to and the text we want to add to that label. In our case, we’re setting it to the current date.

lv_label_set_text(text_label_date, current_date.c_str());

The following lines align the text label. You can use the lv_obj_align() function. Pass as arguments, the LVGL object, the alignment and x and y offsets in pixels.

lv_obj_align(text_label_date, LV_ALIGN_CENTER, 70, -70);

Then, we can set the font type and size using the lv_style_set_text_font() function. We pass as argument the style object we’re referring to and the font type.

lv_obj_set_style_text_font((lv_obj_t*) text_label_date, &lv_font_montserrat_26, 0);

For the text_label_date we’re also setting a custom text teal color:

lv_obj_set_style_text_color((lv_obj_t*) text_label_date, lv_palette_main(LV_PALETTE_TEAL), 0);

A similar procedure is applied to all other labels (temperature, humidity, description, time, and location).

lv_obj_t * weather_image_temperature = lv_image_create(lv_screen_active());
lv_image_set_src(weather_image_temperature, &image_weather_temperature);
lv_obj_align(weather_image_temperature, LV_ALIGN_CENTER, 30, -25);
text_label_temperature = lv_label_create(lv_screen_active());
lv_label_set_text(text_label_temperature, String("      " + temperature + degree_symbol).c_str());
lv_obj_align(text_label_temperature, LV_ALIGN_CENTER, 70, -25);
lv_obj_set_style_text_font((lv_obj_t*) text_label_temperature, &lv_font_montserrat_22, 0);

lv_obj_t * weather_image_humidity = lv_image_create(lv_screen_active());
lv_image_set_src(weather_image_humidity, &image_weather_humidity);
lv_obj_align(weather_image_humidity, LV_ALIGN_CENTER, 30, 20);
text_label_humidity = lv_label_create(lv_screen_active());
lv_label_set_text(text_label_humidity, String("   " + humidity + "%").c_str());
lv_obj_align(text_label_humidity, LV_ALIGN_CENTER, 70, 20);
lv_obj_set_style_text_font((lv_obj_t*) text_label_humidity, &lv_font_montserrat_22, 0);

text_label_weather_description = lv_label_create(lv_screen_active());
lv_label_set_text(text_label_weather_description, weather_description.c_str());
lv_obj_align(text_label_weather_description, LV_ALIGN_BOTTOM_MID, 0, -40);
lv_obj_set_style_text_font((lv_obj_t*) text_label_weather_description, &lv_font_montserrat_18, 0);

// Create a text label for the time and timezone aligned center in the bottom of the screen
text_label_time_location = lv_label_create(lv_screen_active());
lv_label_set_text(text_label_time_location, String("Last Update: " + last_weather_update + "  |  " + location).c_str());
lv_obj_align(text_label_time_location, LV_ALIGN_BOTTOM_MID, 0, -10);
lv_obj_set_style_text_font((lv_obj_t*) text_label_time_location, &lv_font_montserrat_12, 0);
lv_obj_set_style_text_color((lv_obj_t*) text_label_time_location, lv_palette_main(LV_PALETTE_GREY), 0);

Timer

To update the data on the screen, we can create an LVGL timer that will run a specific function periodically. In this case, we’ll update it every 10 minutes. Create an LVGL timer called timer and assign the timer_cb callback function.

lv_timer_t * timer = lv_timer_create(timer_cb, 600000, NULL);
lv_timer_ready(timer);;

Timer Callback Function

The timer_cb function runs every 10 minutes. Each time the callback function runs, we get the latest weather data from the API and update the GUI.

static void timer_cb(lv_timer_t * timer){
  LV_UNUSED(timer);
  get_weather_data();
  get_weather_description(weather_code);
  
(...)

Finally, we set all the text labels to the current data returned from the API:

lv_label_set_text(text_label_date, current_date.c_str());
lv_label_set_text(text_label_temperature, String("      " + temperature + degree_symbol).c_str());
lv_label_set_text(text_label_humidity, String("   " + humidity + "%").c_str());
lv_label_set_text(text_label_weather_description, weather_description.c_str());
lv_label_set_text(text_label_time_location, String("Last Update: " + last_weather_update + "  |  " + location).c_str());

loop()

In the loop(), you can add any other tasks that you need your ESP32 to do like in any regular Arduino sketch. In our case, we won’t add any tasks to the loop(), but to keep LVGL running and detecting events, you always need to add the following lines to your loop().

void loop() {
  lv_task_handler();   // let the GUI do its work
  lv_tick_inc(5);         // tell LVGL how much time has passed
  delay(5);                 // let this time pass
}

Demonstration

Upload the code to your board. Go to Tools > Board and select ESP32 > ESP32 Dev Module. Then, select the right COM port in Tools > Port.

If you see an Error like this: “Sketch too big” during the uploading process, in Arduino IDE go to Tools > Partition scheme > choose anything that has more than 1.4MB APP, for example: “Huge APP (3MB No OTA/1MB SPIFFS“.

Finally, click the upload button.

After a few seconds, the weather info will be displayed on the screen as shown in the picture below.

Wrapping Up

In this tutorial, you’ve created a simple weather station with your Cheap Yellow Display (CYD) board using the LVGL library.

We hope you found this tutorial useful. We’re preparing more guides about this board, so stay tuned. If you would like to learn more about creating graphical user interfaces using the LVGL library with the ESP32, check out our latest eBook:

• Learn LVGL: Build GUIs for ESP32 Projects (eBook)

Other guides you might like reading:

• Getting Started with ESP32 Cheap Yellow Display Board – CYD (ESP32-2432S028R)
• ESP32 Touchscreen On/Off Button – Cheap Yellow Display (ESP32-2432S028R)
• ESP32 Cheap Yellow Display (CYD) Pinout (ESP32-2432S028R)
• LVGL with ESP32 Cheap Yellow Display Board (ESP32-2432S028R)

To learn more about the ESP32, make sure to take a look at our resources:

• Learn ESP32 with Arduino IDE (eBook)
• SMART HOME with Raspberry Pi, ESP32, and ESP8266 eBook
• Free ESP32 Guides and Tutorials