UdpNTPClient_LAN8720.ino

/****************************************************************************************************************************
  UdpNTPClient_LAN8720.ino - Simple Arduino web server sample for ESP8266 AT-command shield
  For STM32 with built-in Ethernet LAN8742A (Nucleo-144, DISCOVERY, etc) or W5x00/ENC28J60 shield/module

  EthernetWebServer_STM32 is a library for the STM32 running Ethernet WebServer

  Based on and modified from ESP8266 https://github.com/esp8266/Arduino/releases
  Built by Khoi Hoang https://github.com/khoih-prog/EthernetWebServer_STM32
  Licensed under MIT license
 *****************************************************************************************************************************/
/*
  Currently support
  1) STM32 boards with built-in LAN8742A Ethernet (to use USE_BUILTIN_ETHERNET = true) such as :
     - Nucleo-144 (F429ZI, F767ZI)
     - Discovery (STM32F746G-DISCOVERY)
     - STM32 boards (STM32F/L/H/G/WB/MP1) with 32K+ Flash, with Built-in Ethernet,
     - See How To Use Built-in Ethernet at (https://github.com/khoih-prog/EthernetWebServer_STM32/issues/1)
  2) STM32 boards with LAN8720 Ethernet (to use USE_BUILTIN_ETHERNET and USING_LAN8720 = true) such as :
     - BLACK_F407XX (BLACK_F407VE, BLACK_F407VG, BLACK_F407ZE, BLACK_F407ZG, BLACK_F407VE-mini), NUCLEO_F429ZI, DISCO_F746NG,
       NUCLEO_F7x6ZG
  3) STM32F/L/H/G/WB/MP1 boards (with 32+K Flash) running ENC28J60 shields (to use USE_BUILTIN_ETHERNET = false)
  4) STM32F/L/H/G/WB/MP1 boards (with 32+K Flash) running W5x00 shields
*/

#include "defines.h"

char timeServer[]         = "time.nist.gov";  // NTP server
unsigned int localPort    = 2390;             // local port to listen for UDP packets

const int NTP_PACKET_SIZE = 48;       // NTP timestamp is in the first 48 bytes of the message
const int UDP_TIMEOUT     = 2000;     // timeout in miliseconds to wait for an UDP packet to arrive

byte packetBuffer[NTP_PACKET_SIZE];   // buffer to hold incoming and outgoing packets

// A UDP instance to let us send and receive packets over UDP
EthernetUDP Udp;

// send an NTP request to the time server at the given address
void sendNTPpacket(char *ntpSrv)
{
  // set all bytes in the buffer to 0
  memset(packetBuffer, 0, NTP_PACKET_SIZE);
  // Initialize values needed to form NTP request
  // (see URL above for details on the packets)

  packetBuffer[0] = 0b11100011;   // LI, Version, Mode
  packetBuffer[1] = 0;     // Stratum, or type of clock
  packetBuffer[2] = 6;     // Polling Interval
  packetBuffer[3] = 0xEC;  // Peer Clock Precision
  // 8 bytes of zero for Root Delay & Root Dispersion
  packetBuffer[12]  = 49;
  packetBuffer[13]  = 0x4E;
  packetBuffer[14]  = 49;
  packetBuffer[15]  = 52;

  // all NTP fields have been given values, now
  // you can send a packet requesting a timestamp:
  Udp.beginPacket(ntpSrv, 123); //NTP requests are to port 123

  Udp.write(packetBuffer, NTP_PACKET_SIZE);

  Udp.endPacket();
}

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

  delay(2000);

  Serial.println("\nStart UdpNTPClient_LAN8720 on " + String(BOARD_NAME) + ", using " + String(SHIELD_TYPE));
  Serial.println(ETHERNET_WEBSERVER_STM32_VERSION);

  // start the ethernet connection and the server:
  // Use DHCP dynamic IP and random mac
  uint16_t index = millis() % NUMBER_OF_MAC;
  // Use Static IP
  //Ethernet.begin(mac[index], ip);
  Ethernet.begin(mac[index]);

  // you're connected now, so print out the data
  Serial.print(F("You're connected to the network, IP = "));
  Serial.println(Ethernet.localIP());

  Udp.begin(localPort);
}

void loop()
{
  sendNTPpacket(timeServer); // send an NTP packet to a time server

  // wait for a reply for UDP_TIMEOUT miliseconds
  unsigned long startMs = millis();

  while (!Udp.available() && (millis() - startMs) < UDP_TIMEOUT) {}

  // if there's data available, read a packet
  int packetSize = Udp.parsePacket();

  if (packetSize)
  {
    Serial.print(F("UDP Packet received, size "));
    Serial.println(packetSize);
    Serial.print(F("From "));
    IPAddress remoteIp = Udp.remoteIP();
    Serial.print(remoteIp);
    Serial.print(F(", port "));
    Serial.println(Udp.remotePort());

    // We've received a packet, read the data from it into the buffer
    Udp.read(packetBuffer, NTP_PACKET_SIZE);

    // the timestamp starts at byte 40 of the received packet and is four bytes,
    // or two words, long. First, esxtract the two words:

    unsigned long highWord = word(packetBuffer[40], packetBuffer[41]);
    unsigned long lowWord = word(packetBuffer[42], packetBuffer[43]);

    // combine the four bytes (two words) into a long integer
    // this is NTP time (seconds since Jan 1 1900):
    unsigned long secsSince1900 = highWord << 16 | lowWord;
    Serial.print(F("Seconds since Jan 1 1900 = "));
    Serial.println(secsSince1900);

    // now convert NTP time into )everyday time:
    Serial.print(F("Unix time = "));
    // Unix time starts on Jan 1 1970. In seconds, that's 2208988800:
    const unsigned long seventyYears = 2208988800UL;
    // subtract seventy years:
    unsigned long epoch = secsSince1900 - seventyYears;
    // print Unix time:
    Serial.println(epoch);

    // print the hour, minute and second:
    Serial.print(F("The UTC time is "));       // UTC is the time at Greenwich Meridian (GMT)
    Serial.print((epoch  % 86400L) / 3600); // print the hour (86400 equals secs per day)
    Serial.print(F(":"));

    if (((epoch % 3600) / 60) < 10)
    {
      // In the first 10 minutes of each hour, we'll want a leading '0'
      Serial.print(F("0"));
    }

    Serial.print((epoch  % 3600) / 60); // print the minute (3600 equals secs per minute)
    Serial.print(F(":"));

    if ((epoch % 60) < 10)
    {
      // In the first 10 seconds of each minute, we'll want a leading '0'
      Serial.print(F("0"));
    }

    Serial.println(epoch % 60); // print the second
  }

  // wait ten seconds before asking for the time again
  delay(10000);
}