/* 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 #include #include int status = WL_IDLE_STATUS; char ssid[] = "mynetwork"; // your network SSID (name) char pass[] = "mypassword"; // your network password int keyIndex = 0; // your network key Index number (needed only for WEP) unsigned int localPort = 2390; // local port to listen for UDP packets IPAddress timeServer(129, 6, 15, 28); // 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 WiFiUDP Udp; 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 } // check for the presence of the shield: if (WiFi.status() == WL_NO_SHIELD) { Serial.println("WiFi shield not present"); // don't continue: while (true); } String fv = WiFi.firmwareVersion(); if (fv != "1.1.0") { Serial.println("Please upgrade the firmware"); } // attempt to connect to Wifi network: while (status != WL_CONNECTED) { Serial.print("Attempting to connect to SSID: "); Serial.println(ssid); // Connect to WPA/WPA2 network. Change this line if using open or WEP network: status = WiFi.begin(ssid, pass); // wait 10 seconds for connection: delay(10000); } Serial.println("Connected to wifi"); printWifiStatus(); Serial.println("\nStarting connection to server..."); 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); Serial.println(Udp.parsePacket()); if (Udp.parsePacket()) { Serial.println("packet received"); // 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 } // 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(IPAddress& address) { //Serial.println("1"); // 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) //Serial.println("2"); 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; //Serial.println("3"); // 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 //Serial.println("4"); Udp.write(packetBuffer, NTP_PACKET_SIZE); //Serial.println("5"); Udp.endPacket(); //Serial.println("6"); } void printWifiStatus() { // print the SSID of the network you're attached to: Serial.print("SSID: "); Serial.println(WiFi.SSID()); // print your WiFi shield's IP address: IPAddress ip = WiFi.localIP(); Serial.print("IP Address: "); Serial.println(ip); // print the received signal strength: long rssi = WiFi.RSSI(); Serial.print("signal strength (RSSI):"); Serial.print(rssi); Serial.println(" dBm"); }