ESP32 NTP Digital Clock with Timezone and Daylight Saving Time

In this tutorial, you’ll create an ESP32 internet-connected digital clock that you can adjust for your timezone, and that automatically handles daylight saving time. The ESP32 gets the current time from an NTP server and displays it on a TM1637 4-digit 7-segment LED display, similar to classic digital clocks. The ESP32 will be programmed using Arduino IDE.
This is a great tutorial to learn about the TM1637 7-segment display and about getting time from an NTP server. For in-depth tutorials about these subjects, check the following articles:
ESP32 NTP Time – Setting Up Timezones and Daylight Saving Time
ESP32 with TM1637 4-Digit LED 7-Segment Display (Arduino IDE)
Prerequisites
Before proceeding, make sure you have the Arduino IDE installed and the ESP32 boards. Follow the next tutorial if you haven’t already:
Installing ESP32 Board in Arduino IDE 2 (Windows, Mac OS X, Linux)
Project Overview
In this tutorial, we’ll get the time from the NTP server and display it on the TM1637 4-Digit 7-Segment Display.
TM1637 4-Digit LED 7-Segment Display
The
TM1637 4-Digit LED 7-Segment display
is a display module that combines four 7-segment digits in a single display that can be controlled via the TM1637 driver. The particular module we’re using here has four digits separated by a colon between the second and third digits. This layout is ideal for creating a digital clock, with the hour on one side of the colon and the minutes on the other.
NTP (Network Time Protocol)
We’ll get the time for your timezone using NTP (network time protocol) with adjustment for daylight saving time.
NTP stands for Network Time Protocol, and it is a networking protocol for clock synchronization between computer systems. In other words, it is used to synchronize computer clock times in a network.
There are NTP servers like
pool.ntp.org
that anyone can use to request time as a client. In this case, the ESP32 is an NTP Client that requests time from an NTP Server (
pool.ntp.org
).
To learn more about getting time with the ESP32, you can read the following guides:
ESP32 NTP Client-Server: Get Date and Time (Arduino IDE)
ESP32 NTP Time – Setting Up Timezones and Daylight Saving Time
Project Layout
Here’s a quick overview of the steps we need to follow to create this project:
Initialize the display.
Initialize Wi-Fi and connect the ESP32 to your local network so that it can get data from the internet.
Initialize time for your specified timezone (takes into account daylight saving time).
Show the time on the display (blink the colon between the numbers every second).
Every hour, connect to the NTP server to resync the timer—prevents drifting from the ESP32 internal clock.
Parts Required
For this project, you need the following parts:
ESP32 board
– any model of your choice
TM1637 4-Digit 7-Segment Display
Jumper Wires
You can use the preceding links or go directly to
MakerAdvisor.com/tools
to find all the parts for your projects at the best price!
Wiring the TM1637 4-Digit 7-Segment Display to the ESP32
Wiring the display to the ESP32 is quite simple, as it only requires two digital pins:
CLK
and
DI/O
TM1637 Display
ESP32
CLK
Any digital pin (for example:
GPIO 19
)*
DIO
Any digital pin (for example:
GPIO 18
)*
VCC
VIN
GND
GND
* you can use any other suitable GPIOs. Check the ESP32 Pinout Guide:
ESP32 Pinout Reference: Which GPIO pins should you use?
ESP32-S3 DevKitC Pinout Reference Guide: GPIOs Explained
We’ll connect the CLK pin to
GPIO 19
, and the DIO pin to
GPIO 18
, but you can use a different combination of pins.
Installing the TM1637 Library
There are several libraries to interface the TM1637 display with the ESP32. We’ll use the
TM1637.h library by avishorp
(even though it hasn’t been updated for several years, it still works well, and it’s very easy to use).
You can install the library via the Arduino IDE library Manager. Search for
TM1637
and install the library by avishorp.
Code – ESP32 with TM1637 Digital Clock
You can upload the following code to your ESP32 board. You need to:
Insert your SSID and password
Insert your timezone string. A list can be found on
nayarsystems github’s
/*
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.
*/
#include <WiFi.h>
#include "time.h"
#include <TM1637Display.h>

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

// TM1637 pins
#define CLK 19
#define DIO 18

TM1637Display display(CLK, DIO);

// Timezone (Lisbon / Portugal)
// Change if needed - See list of timezones strings: https://github.com/nayarsystems/posix_tz_db/blob/master/zones.csv
const char* TZ_INFO = "WET0WEST,M3.5.0/1,M10.5.0";

// Init Wifi
void initWiFi() {
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(1000);
Serial.println("Connecting to WiFi..");
}
}

// Initialize Time with the specified timezone
void initTime() {
configTime(0, 0, "pool.ntp.org");
setenv("TZ", TZ_INFO, 1);
tzset();
}

// display the time on the screen
void displayTime() {

// blinking colon
static bool colon = false;
colon = !colon;

// get the current time
struct tm timeinfo;
if (!getLocalTime(&timeinfo)) {
return;
}

int hours = timeinfo.tm_hour; // get hours (0–23)
int minutes = timeinfo.tm_min; // get minutes (0–59)

// move hours to the left two digits
int hourPart = hours * 100;

// combine hours and minutes into HHMM
int value = hourPart + minutes;

// control the colon (for blinking colon)
uint8_t colonMask;
if (colon == true) {
colonMask = 0b01000000; // turn colon ON
} else {
colonMask = 0; // turn colon OFF
}

display.showNumberDecEx(
value,
colonMask, // blink colon
true // leading zeros
);
}

void setup() {
Serial.begin(115200);

display.setBrightness(7);
display.clear();

initWiFi();
initTime();
}

void loop() {
displayTime();
delay(1000);
}
How Does the Code Work?
Let’s take a quick look at the code to see how it works.
Include Libraries
Start by including the required libraries.
#include <WiFi.h>
#include "time.h"
#include <TM1637Display.h>
Network Credentials
Insert your network credentials on the following lines.
// Replace with your network credentials
const char* ssid = "REPLACE_WITH_YOUR_SSID";
const char* password = "REPLACE_WITH_YOUR_PASSWORD";
FreeRTOS Timer Handle
We create a handle for the FreeRTOS timer we’ll create in the code. This timer will periodically call a callback function every hour (
SYNC_INTERVAL
) that will make a new request to the NTP server to get the time.
// Resync clock
TimerHandle_t syncTimer = NULL;
const unsigned long SYNC_INTERVAL = 3600000UL; // 1 hour (3600000 ms)
To learn more about FreeRTOS timers, check this tutorial:
ESP32 with FreeRTOS: Software Timers/Timer Interrupts (Arduino IDE).
Initialize the Display
Set the TM1637 pins and create an instance for the display called
display
// TM1637 pins
#define CLK 19
#define DIO 18

TM1637Display display(CLK, DIO);
Timezone
Insert your timezone string in the following line. You can find a
list of timezone strings
. In my case, my timezone is Lisbon/Portugal, so it will look as follows:
const char* TZ_INFO = "WET0WEST,M3.5.0/1,M10.5.0";
Initialize Wi-Fi
The following function initializes Wi-Fi and connects the ESP32 to your local network. This will be called later on in the
setup()
// Init Wifi
void initWiFi() {
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(1000);
Serial.println("