ESP8266 WiFi Shield and Timeserver
Posted: Fri Jun 09, 2017 7:38 amI want to get the time from a time server. No example of the internet is running. It seems that UDP doesn't work. Has somebody an example ? Thanks. Klaus-Dieter
Code: Select all
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
const unsigned long seventyYears = 2208988800UL;
WiFiUDP udp;
IPAddress ntphostip;
WiFi.hostByName("time.nist.gov", ntphostip);
String str = "NTP IPAddr : ";
str += ntphostip.toString();
Serial.println(str);
udp.begin(2390);
memset(packetBuffer, 0, NTP_PACKET_SIZE);
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
packetBuffer[12] = 49;
packetBuffer[13] = 0x4E;
packetBuffer[14] = 49;
packetBuffer[15] = 52;
udp.beginPacket(ntphostip, 123); //NTP requests are to port 123
udp.write(packetBuffer, NTP_PACKET_SIZE);
udp.endPacket();
delay(2000);
int cb = udp.parsePacket();
if (!cb) {
Serial.println("no NTP response");
}
else {
Serial.print("packet received, length=");
Serial.println(cb);
udp.read(packetBuffer, NTP_PACKET_SIZE); // read the packet into the buffer
unsigned long highWord = word(packetBuffer[40], packetBuffer[41]);
unsigned long lowWord = word(packetBuffer[42], packetBuffer[43]);
unsigned long secsSince1900 = highWord << 16 | lowWord;
Serial.print("Seconds since Jan 1 1900 = " );
Serial.println(secsSince1900);
Serial.print("Unix time (seconds since 1970) = ");
Serial.println(secsSince1900 - seventyYears);
