UdpNTPClient.ino

/****************************************************************************************************************************
  UdpNTPClient.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
 *****************************************************************************************************************************/

#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);

  while (!Serial && millis() < 5000);

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

#if USE_ETHERNET_GENERIC
  Serial.println(ETHERNET_GENERIC_VERSION);
#endif

  Serial.println(ETHERNET_WEBSERVER_STM32_VERSION);

#if !(USE_BUILTIN_ETHERNET)
#if (USING_SPI2)
#if defined(CUR_PIN_MISO)
  ET_LOGWARN(F("Default SPI pinout:"));
  ET_LOGWARN1(F("MOSI:"), CUR_PIN_MOSI);
  ET_LOGWARN1(F("MISO:"), CUR_PIN_MISO);
  ET_LOGWARN1(F("SCK:"),  CUR_PIN_SCK);
  ET_LOGWARN1(F("SS:"),   CUR_PIN_SS);
  ET_LOGWARN(F("========================="));
#endif
#else
  ET_LOGWARN(F("Default SPI pinout:"));
  ET_LOGWARN1(F("MOSI:"), MOSI);
  ET_LOGWARN1(F("MISO:"), MISO);
  ET_LOGWARN1(F("SCK:"),  SCK);
  ET_LOGWARN1(F("SS:"),   SS);
  ET_LOGWARN(F("========================="));
#endif
#endif

#if !(USE_BUILTIN_ETHERNET || USE_UIP_ETHERNET)
  // For other boards, to change if necessary
#if ( USE_ETHERNET_GENERIC || USE_ETHERNET_ENC )
  Ethernet.init (USE_THIS_SS_PIN);

#elif USE_CUSTOM_ETHERNET
  // You have to add initialization for your Custom Ethernet here
  // This is just an example to setCSPin to USE_THIS_SS_PIN, and can be not correct and enough
  //Ethernet.init(USE_THIS_SS_PIN);

#endif  //( ( USE_ETHERNET_GENERIC || USE_ETHERNET_ENC )
#endif

  // 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]);

  Serial.print(F("Connected! IP address: "));
  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);
}