ESP32 CYD GPS Tracker: Build a Portable Location Display with LVGL

/*********
  ESP32 CYD with LVGL - GPS Location, Date, and Time Display
  Complete tutorial: https://RandomNerdTutorials.com/esp32-cyd-lvgl-gps-location/
*********/

#include <lvgl.h>
#include <TFT_eSPI.h>
#include <TinyGPS++.h>
#include "gps_image.h"  // Custom map icon

// --- GPS Serial Configuration ---
#define RXD2 22          // GPS TX -> ESP32 RX (Serial2)
#define TXD2 27          // GPS RX -> ESP32 TX (Serial2)
#define GPS_BAUD 9600    // NEO-6M default baud rate

TinyGPSPlus gps;                 // GPS parser object
HardwareSerial gpsSerial(2);     // Use UART2 for GPS

// --- Display Dimensions ---
#define SCREEN_WIDTH 240
#define SCREEN_HEIGHT 320

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

// --- GPS Data Variables (as Strings for display) ---
String current_date;
String utc_time;
String latitude;
String longitude;
String altitude;
String speed;
String hdop;
String satellites;

// --- LVGL Logging ---
void log_print(lv_log_level_t level, const char * buf) {
  LV_UNUSED(level);
  Serial.println(buf);
  Serial.flush();
}

// Helper to format time with leading zeros
String format_time(int time_val) {
  return (time_val < 10) ? "0" + String(time_val) : String(time_val);
}

// --- LVGL UI Elements ---
static lv_obj_t * label_date;
static lv_obj_t * label_latitude;
static lv_obj_t * label_longitude;
static lv_obj_t * label_altitude;
static lv_obj_t * label_speed;
static lv_obj_t * label_utc_time;
static lv_obj_t * label_hdop_satellites;
static lv_obj_t * label_gps_data;

// --- Timer Callback: Updates all labels with latest GPS data ---
static void timer_cb(lv_timer_t * timer) {
  LV_UNUSED(timer);
  
  lv_label_set_text(label_date, current_date.c_str());
  lv_label_set_text(label_hdop_satellites, 
                    String("HDOP " + hdop + "  SAT. " + satellites).c_str());
  
  // Main data block (latitude, longitude, altitude, speed)
  lv_label_set_text(label_gps_data, 
                    String("LAT   " + latitude + 
                           "\nLON   " + longitude + 
                           "\nALT   " + altitude + "m" + 
                           "\nSPEED   " + speed + "km/h").c_str());
  
  lv_label_set_text(label_utc_time, String("UTC TIME - " + utc_time).c_str());
}

// --- Create the LVGL User Interface ---
void create_gui() {
  // Declare the image from gps_image.h
  LV_IMAGE_DECLARE(image_gpsmap);
  
  // Map icon (left side)
  lv_obj_t * img_gpsmap = lv_image_create(lv_screen_active());
  lv_obj_align(img_gpsmap, LV_ALIGN_LEFT_MID, 10, -20);
  lv_image_set_src(img_gpsmap, &image_gpsmap);
  
  // HDOP and satellites info (bottom left)
  label_hdop_satellites = lv_label_create(lv_screen_active());
  lv_label_set_text(label_hdop_satellites, "HDOP --  SAT. --");
  lv_obj_align(label_hdop_satellites, LV_ALIGN_BOTTOM_LEFT, 30, -50);
  lv_obj_set_style_text_font(label_hdop_satellites, &lv_font_montserrat_12, 0);
  lv_obj_set_style_text_color(label_hdop_satellites, lv_palette_main(LV_PALETTE_GREY), 0);
  
  // Date (large, teal color, top center)
  label_date = lv_label_create(lv_screen_active());
  lv_label_set_text(label_date, "----/--/--");
  lv_obj_align(label_date, LV_ALIGN_CENTER, 60, -80);
  lv_obj_set_style_text_font(label_date, &lv_font_montserrat_26, 0);
  lv_obj_set_style_text_color(label_date, lv_palette_main(LV_PALETTE_TEAL), 0);
  
  // "LOCATION" heading
  lv_obj_t * heading_location = lv_label_create(lv_screen_active());
  lv_label_set_text(heading_location, "LOCATION");
  lv_obj_align(heading_location, LV_ALIGN_CENTER, 50, -40);
  lv_obj_set_style_text_font(heading_location, &lv_font_montserrat_20, 0);
  
  // Main GPS data block (lat, lon, alt, speed)
  label_gps_data = lv_label_create(lv_screen_active());
  lv_label_set_text(label_gps_data, 
                    "LAT   --\nLON   --\nALT   --m\nSPEED   --km/h");
  lv_obj_align(label_gps_data, LV_ALIGN_CENTER, 60, 20);
  lv_obj_set_style_text_font(label_gps_data, &lv_font_montserrat_14, 0);
  
  // UTC time (teal, bottom center)
  label_utc_time = lv_label_create(lv_screen_active());
  lv_label_set_text(label_utc_time, "UTC TIME - --:--:--");
  lv_obj_align(label_utc_time, LV_ALIGN_BOTTOM_MID, 0, -10);
  lv_obj_set_style_text_font(label_utc_time, &lv_font_montserrat_20, 0);
  lv_obj_set_style_text_color(label_utc_time, lv_palette_main(LV_PALETTE_TEAL), 0);
  
  // Create timer to update UI (1ms, but effectively on each loop)
  lv_timer_t * timer = lv_timer_create(timer_cb, 1, NULL);
  lv_timer_ready(timer);
}

// --- Setup ---
void setup() {
  Serial.begin(115200);
  Serial.println("ESP32 CYD GPS Tracker Starting...");

  // Initialize GPS Serial connection
  gpsSerial.begin(GPS_BAUD, SERIAL_8N1, RXD2, TXD2);
  Serial.println("GPS Serial initialized at 9600 baud");

  // Initialize LVGL
  lv_init();
  lv_log_register_print_cb(log_print);

  // Initialize display
  lv_display_t * disp = lv_tft_espi_create(SCREEN_WIDTH, SCREEN_HEIGHT, 
                                            draw_buf, sizeof(draw_buf));
  lv_display_set_rotation(disp, LV_DISPLAY_ROTATION_270);

  // Create the GUI
  create_gui();

  Serial.println("Ready. Waiting for GPS fix...");
}

// --- Main Loop ---
void loop() {
  lv_task_handler();  // Let LVGL handle GUI tasks
  lv_tick_inc(5);     // Tell LVGL time passed
  delay(5);           // Small delay

  // Read and parse GPS data continuously
  while (gpsSerial.available() > 0) {
    gps.encode(gpsSerial.read());
  }

  // Check if location data is updated (typically every 1 second)
  if (gps.location.isUpdated()) {
    // Update all data strings
    latitude = String(gps.location.lat(), 6);
    longitude = String(gps.location.lng(), 6);
    speed = String(gps.speed.kmph(), 2);
    altitude = String(gps.altitude.meters(), 2);
    hdop = String(gps.hdop.value() / 100.0, 2);
    satellites = String(gps.satellites.value());
    
    // Format date: YYYY-MM-DD
    current_date = String(gps.date.year()) + "-" +
                   format_time(gps.date.month()) + "-" +
                   format_time(gps.date.day());
    
    // Format UTC time: HH:MM:SS
    utc_time = format_time(gps.time.hour()) + ":" +
               format_time(gps.time.minute()) + ":" +
               format_time(gps.time.second());

    // Print to Serial Monitor for debugging
    Serial.println("--- GPS Update ---");
    Serial.print("LAT: "); Serial.println(latitude);
    Serial.print("LON: "); Serial.println(longitude);
    Serial.print("Speed: "); Serial.print(speed); Serial.println(" km/h");
    Serial.print("Altitude: "); Serial.print(altitude); Serial.println(" m");
    Serial.print("HDOP: "); Serial.println(hdop);
    Serial.print("Satellites: "); Serial.println(satellites);
    Serial.print("Date: "); Serial.println(current_date);
    Serial.print("UTC Time: "); Serial.println(utc_time);
    Serial.println("-----------------");
  }
}

while (gpsSerial.available() > 0) {
  gps.encode(gpsSerial.read());
}

--- GPS Update ---
LAT: 41.387900
LON: 2.169920
Speed: 0.12 km/h
Altitude: 24.50 m
HDOP: 1.20
Satellites: 8
Date: 2024-11-12
UTC Time: 15:23:45
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