Erriez NTP Client library for Arduino

This is a minimized NTP Client library for Arduino to retrieve UNIX Epoch UTC from NTP time servers.

Library features

• Retrieve UNIX Epoch UTC time from network time servers
• Compatible with time.h
• Timeout handling

Supported hardware

• Arduino UNO with EtherShield (Wiznet W5100 Ethernet controller)
• ESP8266 WiFi
• ESP32 WiFi

Documentation

• Online HTML
• Doxygen PDF

Example output

{c++}
Erriez ESP8266 NTP example
Connecting to 'wifi'...OK
Epoch: 1600025290
UTC:   Sun Sep 13 19:28:10 2020

Example ESP8266 / ESP32

{c++}
#if defined(ARDUINO_ARCH_ESP8266)
#include <ESP8266WiFi.h>
#elif defined(ARDUINO_ARCH_ESP32)
#include <WiFi.h>
#endif

#include <ErriezNTPClient.h>

// WiFi SSID and Password
#define WIFI_SSID           ""
#define WIFI_PASSWORD       ""

// "pool.ntp.org", "time.nist.gov" or NTP server IP address
#define NTP_SERVER          "pool.ntp.org"

ErriezNTPClient ntp(NTP_SERVER);


void setup()
{
    // Initialize serial
    delay(500);
    Serial.begin(115200);
    Serial.println(F("\nErriez NTP client ESP8266 / ESP32 example"));

    // Initialize WiFi
    Serial.print(F("Connecting to '"));
    Serial.print(WIFI_SSID);
    Serial.print(F("'"));

    // Connect to your WiFi router
    WiFi.begin(WIFI_SSID, WIFI_PASSWORD);

    // Wait for connection
    while (WiFi.status() != WL_CONNECTED) {
        delay(500);
        Serial.print(".");
    }
    Serial.println("OK");
}

void loop()
{
    time_t t;

    // Get epoch
    t = ntp.getEpoch();

    // Print result
    if (t > 0) {
        Serial.print(F("Epoch: "));
        Serial.println((uint32_t)t);
        Serial.print(F("UTC:   "));
        Serial.println(ctime(&t));
    } else {
        Serial.println(F("Timeout"));
    }

    delay(10000);
}

Example AVR (ATMega328 / ATMega2560)

{c++}
#include <Ethernet.h>
#include <ErriezNTPClient.h>

// "pool.ntp.org", "time.nist.gov" or NTP server IP address
#define NTP_SERVER          "pool.ntp.org"

ErriezNTPClient ntp(NTP_SERVER);

// Newer Ethernet shields have a MAC address printed on a sticker on the shield
uint8_t mac[] = {
    0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED
};


void setup()
{
    // Initialize serial
    delay(500);
    Serial.begin(115200);
    Serial.println(F("\nErriez NTP client AVR example"));

    // Start Ethernet and UDP
    if (!Ethernet.begin(mac)) {
        Serial.println(F("Failed to configure Ethernet using DHCP"));

        // Check for Ethernet hardware present
        if (Ethernet.hardwareStatus() == EthernetNoHardware) {
            Serial.println(F("Ethernet shield was not found."));
        } else if (Ethernet.linkStatus() == LinkOFF) {
            Serial.println(F("Ethernet cable is not connected."));
        }
    }
}

void loop()
{
    time_t t;

    // Get epoch
    t = ntp.getEpoch();

    // Print result
    if (t > 0) {
        Serial.print(F("Epoch: "));
        Serial.println((uint32_t)t);

        // A UNIX offset is needed for AVR target
        t -= UNIX_OFFSET;

        Serial.print(F("UTC:   "));
        Serial.println(ctime(&t));
    } else {
        Serial.println(F("Timeout"));
    }

    delay(10000);
}

Library installation

Please refer to the Wiki page.

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