Part 3 of 3
//***********************************NTP***********************************
void printDigits(int digits){
// utility for digital clock display: prints preceding colon and leading 0
if(digits < 10)
TimeString = TimeString + "0";
TimeString = TimeString + digits;
}
/*-------- NTP code ----------*/
const int NTP_PACKET_SIZE = 48; // NTP time is in the first 48 bytes of message
byte packetBuffer[NTP_PACKET_SIZE]; //buffer to hold incoming & outgoing packets
time_t getNtpTime()
{
while (Udp.parsePacket() > 0) ; // discard any previously received packets
sendNTPpacket(timeServer);
uint32_t beginWait = millis();
while (millis() - beginWait < 1500) {
int size = Udp.parsePacket();
if (size >= NTP_PACKET_SIZE) {
Udp.read(packetBuffer, NTP_PACKET_SIZE); // read packet into the buffer
unsigned long secsSince1900;
// convert four bytes starting at location 40 to a long integer
secsSince1900 = (unsigned long)packetBuffer[40] << 24;
secsSince1900 |= (unsigned long)packetBuffer[41] << 16;
secsSince1900 |= (unsigned long)packetBuffer[42] << 8;
secsSince1900 |= (unsigned long)packetBuffer[43];
return secsSince1900 - 2208988800UL + timeZone * SECS_PER_HOUR;
}
}
Serial.println(F("No NTP Response :-("));
return 0; // return 0 if unable to get the time
}
void updatetime()
{
if (timeStatus() != timeNotSet){
if (now() != prevDisplay) { //update the display only if time has changed
prevDisplay = now();
digitalClockDisplay();
}
}
}
void digitalClockDisplay(){
// digital clock display of the time
TimeString = "";
printDigits(month());
TimeString = TimeString + "/";
printDigits(day());
TimeString = TimeString + "/";
printDigits(year());
TimeString = TimeString + " - ";
printDigits(hour());
TimeString = TimeString + ":";
printDigits(minute());
TimeString = TimeString + ":";
printDigits(second());
goto skipit;
Serial.print(TimeString);
Serial.println();
skipit:
;
}
// send an NTP request to the time server at the given address
void 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();
}