| /* | |
| 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. | |
| */ | |
| 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 native USB port 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); | |
| 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"); | |
| } | |