How to use NTP

Get the time with NTP. For this to work, the Ethernet library must be usable. First let's instantiate.

#include <NTP.h>

NTPClient ntpclient;

Please check the official reference regarding the initialization and usage of the Ethernet library. In addition, the code to set the IP address with commonly used DHCP is as follows.

#include <Ethernet.h>

byte mac[] = {
  0x00, 0xAA, 0xBB, 0xCC, 0xDE, 0x02
};

Ethernet.begin(mac);

Communicate by NTP and get time information.

uint32_t unix_time = 0;

ntpclient.begin();
ntpclient.getTime("ntp.nict.jp", &unix_time);

If the return value of getTime function is negative, it means the acquisition has failed, so let's retry. If you are successful, all that's left to do is to call the setTime function with the Time library.