11-1 網路校時程式

網路校時程式

下載：https://github.com/brucetsao/techbang/tree/master/201602

網路校時測試程式(UdpNtpClient)
/*

 Udp NTP Client

 Get the time from a Network Time Protocol (NTP) time server
 Demonstrates use of UDP sendPacket and ReceivePacket
 For more on NTP time servers and the messages needed to communicate with them,
 see http://en.wikipedia.org/wiki/Network_Time_Protocol

 created 4 Sep 2010
 by Michael Margolis
 modified 9 Apr 2012
 by Tom Igoe

 This code is in the public domain.

 */

#include <SPI.h>
#include <Ethernet.h>
#include <EthernetUdp.h>

// Enter a MAC address for your controller below.
// Newer Ethernet shields have a MAC address printed on a sticker on the shield
byte mac[] = {
  0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF
};
IPAddress ip(192, 168, 2, 200);     //fix ip
IPAddress dnServer(168, 95, 1, 1);    //dns ip
// the router's gateway address:
IPAddress gateway(192, 168, 2, 1);    //gateway ip
// the subnet:
IPAddress subnet(255, 255, 255, 0);     //sub mask


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

char timeServer[] = "time.nist.gov"; // time.nist.gov 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;
int Ntpyr,Ntpmon,Ntpday,Ntphr,Ntpmin,Ntpsec ;

void setup()
{
  // Open serial communications and wait for port to open:
  Serial.begin(9600);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for Leonardo only
  }


  // start Ethernet and UDP
  if (Ethernet.begin(mac) == 0) {
    Serial.println("Failed to configure Ethernet using DHCP");
    // no point in carrying on, so do nothing forevermore:
  Ethernet.begin(mac, ip, dnServer, gateway, subnet);

  }
  Udp.begin(localPort);
}

void loop()
{
  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 + 8 * 60*60 ;
    // print Unix time:
    Serial.println(epoch);
    Ntphr = (epoch  % 86400L) / 3600 ;
    Ntpmin = (epoch  % 3600) / 60 ;
    Ntpsec = epoch % 60 ;
    // print the hour, minute and second:
    Serial.print("The Taiwan time is ");       // UTC is the time at Greenwich Meridian (GMT)
    
    Serial.print(print2digits(Ntphr)); // print the hour (86400 equals secs per day)
    Serial.print(':');
    Serial.print(print2digits(Ntpmin)); // print the minute (3600 equals secs per minute)
    Serial.print(':');

    Serial.println(print2digits(Ntpsec)); // print the second
  }
  // wait ten seconds before asking for the time again
  delay(10000);
}

// send an NTP request to the time server at the given address
unsigned long sendNTPpacket(char* 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();
}

String  print2digits(int number) {
  String ttt ;
  if (number >= 0 && number < 10) 
  {
     ttt =String("0")+String(number);
  }
  else
  {
     ttt =String(number);
  }
   return ttt ;
}

String  print4digits(int number) {
  String ttt ;
     ttt =String(number);
   return ttt ;
}

參考資料：http://www.techbang.com/posts/40869-smart-home-arduino-internet-soul-internet-school