Arduino - Servidor NTP time server

#include <SPI.h>

#include <Time.h>

#include <Ethernet.h>

#include <EthernetUdp.h>

#include <Sunrise.h>

Sunrise mySunrise(41.37,2.18,+1);

  #define offset 1970

  byte mac [ ] = {

  0xDE , 0xAD , 0xBE , 0xEF , 0xFE , 0xED }

;

IPAddress ip ( 192 , 168 , 0 , 17) ;

IPAddress dns1 ( 192 , 168 , 0 , 101 ) ;

IPAddress gateway ( 192 , 168 , 0 , 101 ) ;

IPAddress subnet ( 255 , 255 , 255 , 0 ) ;

EthernetServer server ( 82 ) ;

unsigned int localPort = 8888; // local port to listen for UDP packets

IPAddress timeServer(132, 163, 4, 101); // local NTP server

const int NTP_PACKET_SIZE= 48; // NTP time stamp is in the first 48 bytes of the message

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;

time_t prevDisplay = 0; // when the digital clock was displayed

long timeZoneOffset = -7200L;//-7200L; // set this to the offset in seconds to your local time;

char isodate[25]; // The current time in ISO format is being stored here

int minuIni=0;

void setup()

{

  // Se abre puerto de comunicación serie:

  //Ethernet.begin(mac); // ip dinamica

  Ethernet . begin ( mac , ip , dns1 , gateway , subnet ) ; // ip fija

  Serial.begin(9600);

  Udp.begin(localPort);

  Serial.println(Ethernet.localIP());

 setSyncProvider(getNtpTime);

  while(timeStatus()== timeNotSet);

  // calcula salida y puesta de sol

    minuIni=minute()+1;

}

void loop(){

 // if (minute()==35) timeZoneOffset = -7200L;

 // if (minute()==39) timeZoneOffset = -3600L;

  Serial.print(hour());

 Serial.print(":");

Serial.print(minute());

  Serial.print(":");

Serial.println(second());

delay(1000);

}

/*-------- NTP code ----------*/

unsigned long getNtpTime()

{

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

  // wait to see if a reply is available

  delay(1000);

// ****************************************************************************************************************

// En la línea inferior Udp.parsePacket() siempre da valor 0 por lo que no está recibiendo respuesta del servidor

 if ( Udp.parsePacket() ) {

    // We've received a packet, read the data from it

    Udp.read(packetBuffer,NTP_PACKET_SIZE); // read the packet into the buffer

    //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;

    // now convert NTP time into Unix time

    // starts on Jan 1 1970. In seconds, that's 2208988800:

    const unsigned long seventyYears = 2208988800UL;

    unsigned long epoch = secsSince1900 - seventyYears;

    return epoch - timeZoneOffset;

  }

  return 0; // return 0 if unable to get the time

}

// send an NTP request to the time server at the given address

unsigned long sendNTPpacket(IPAddress& address)

{

  // 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(address, 123); //NTP requests are to port 123

  Udp.write(packetBuffer,NTP_PACKET_SIZE);

  Udp.endPacket();

}