Internet Clock 1

https://techlogics.net/create-an-internet-clock-with-esp32-oled-128x64-display-live-date-time-tutorial/

#include <U8g2lib.h>
#include <Wire.h>
#include <WiFi.h>
#include <NTPClient.h>
#include <WiFiUdp.h>
#include <time.h>
 
// Replace with your WiFi credentials
const char* ssid     = "Your_wifi_SSID";   
const char* password = "Wifi_password";  
 
// Initialize OLED display (128x64 SH1106)
U8G2_SH1106_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);
 
// NTP Client Setup
WiFiUDP ntpUDP;
NTPClient timeClient(ntpUDP, "pool.ntp.org", 19800, 3600000); // Timezone offset (19800 seconds = UTC +5:30)
 
void setup() {
  // Start serial communication for debugging
  Serial.begin(115200);
   
  // Connect to Wi-Fi
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi...");
  }
  Serial.println("Connected to WiFi");
 
  // Initialize the OLED
  u8g2.begin();
   
  // Start the NTP client
  timeClient.begin();
  timeClient.setTimeOffset(19800); // Indian Standard Time (UTC +5:30)
}
 
void loop() {
  timeClient.update(); // Update time from NTP server
 
  // Get current time in seconds
  unsigned long currentEpoch = timeClient.getEpochTime();
   
  // Convert epoch time (unsigned long) to time_t (signed long)
  time_t currentTime = (time_t)currentEpoch;
 
  // Convert time to time structure
  struct tm* timeInfo;
  timeInfo = localtime(&currentTime);  // Convert to time structure
   
  // Extract time components
  int hours = timeInfo->tm_hour;
  int minutes = timeInfo->tm_min;
  int seconds = timeInfo->tm_sec;
 
  // Extract date components
  int day = timeInfo->tm_mday;
  int month = timeInfo->tm_mon + 1;  // tm_mon is zero-based, so add 1
  int year = timeInfo->tm_year + 1900;  // tm_year is years since 1900, so add 1900
 
  // Extract day of the week (0 = Sunday, 1 = Monday, etc.)
  String daysOfWeek[] = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};
  String dayOfWeek = daysOfWeek[timeInfo->tm_wday];
 
  // Clear the display
  u8g2.clearBuffer();
 
  // Set font size for the clock
  u8g2.setFont(u8g2_font_ncenB18_tr);  // Larger font (18px)
 
  // Format the time
  String timeStr = String(hours) + ":" + (minutes < 10 ? "0" + String(minutes) : String(minutes)) + ":" + (seconds < 10 ? "0" + String(seconds) : String(seconds));
 
  // Calculate the width of the time text to center it
  int textWidth = u8g2.getStrWidth(timeStr.c_str());
 
  // Set the cursor position to center the time text
  int x = (128 - textWidth) / 2;  // Center horizontally on 128x64 screen
  int y = 24;  // Set Y position to the middle of the screen for time
 
  // Draw the time at the center of the screen
  u8g2.setCursor(x, y);
  u8g2.print(timeStr);
 
  // Set font size for the date
  u8g2.setFont(u8g2_font_ncenB10_tr);  // Smaller font (10px) for the date
 
  // Format the date as DD/MM/YYYY with leading zeroes if necessary
  String dayStr = (day < 10) ? "0" + String(day) : String(day);
  String monthStr = (month < 10) ? "0" + String(month) : String(month);
  String dateStr = dayStr + "/" + monthStr + "/" + String(year);
 
  // Calculate the width of the date text to center it
  int dateTextWidth = u8g2.getStrWidth(dateStr.c_str());
 
  // Set the cursor position to center the date text
  int dateX = (128 - dateTextWidth) / 2;  // Center horizontally
  int dateY = 40;  // Move the date 2px up from the previous position
 
  // Draw the date below the time
  u8g2.setCursor(dateX, dateY);
  u8g2.print(dateStr);
 
  // Set font size for the day of the week
  u8g2.setFont(u8g2_font_ncenB10_tr);  // Smaller font (10px) for the day of the week
 
  // Calculate the width of the day of the week text to center it
  int dayOfWeekWidth = u8g2.getStrWidth(dayOfWeek.c_str());
 
  // Set the cursor position to center the day of the week text
  int dayOfWeekX = (128 - dayOfWeekWidth) / 2;  // Center horizontally
  int dayOfWeekY = 56;  // Set Y position below the date text
 
  // Draw the day of the week below the date
  u8g2.setCursor(dayOfWeekX, dayOfWeekY);
  u8g2.print(dayOfWeek);
 
  // Send the buffer to the display
  u8g2.sendBuffer();
 
  delay(1000);  // Update every second
}