Time.cpp

/*
 * Time.cpp
 *
 *  Created on: Jan 16, 2011
 *      Author: Andy
 */



#include "Time.h"

EthernetUDP Udp;

static IPAddress timeServer(192, 43, 244, 18); // time.nist.gov NTP server

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



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

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

void InitializeTime()
{
	Udp.begin(localPort);
	uint32_t epoch = 0; //GetEpoch();
	if (epoch == 0)
	{
		Serial.println("Unable to get updated time");
		Serial.print("Using RTC stored time of: ");
		DateTime dt = RTC.now();
		Serial.println(dt.unixtime());
	}
	else
	{
		Serial.print("Setting RTC to: ");
		Serial.println(epoch, DEC);
		if (!RTC.isrunning())
		{
			Serial.println("RTC is NOT running!");
		}
		RTC.adjust(epoch);
	}
}

unsigned long GetEpoch()
{

	Serial.print("Getting Epoch");

	  sendNTPpacket(timeServer); // send an NTP packet to a time server
	    // wait to see if a reply is available
	  delay(1000);
	  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;
	      Serial.print("Seconds since Jan 1 1900 = " );
	      Serial.println(secsSince1900);

	      // now convert NTP time into everyday time:
	      Serial.print("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("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(':');
	      if ( ((epoch % 3600) / 60) < 10 ) {
	        // In the first 10 minutes of each hour, we'll want a leading '0'
	        Serial.print('0');
	      }
	      Serial.print((epoch  % 3600) / 60); // print the minute (3600 equals secs per minute)
	      Serial.print(':');
	      if ( (epoch % 60) < 10 ) {
	        // In the first 10 seconds of each minute, we'll want a leading '0'
	        Serial.print('0');
	      }
	      Serial.println(epoch %60); // print the second
	      return epoch;
	    }
	  else
	  {
		  return 0;
	  }
}


// 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();
}