#include <ESP8266WiFi.h>
#include <WiFiUdp.h>
char* ssid="SSID"; //WiFi SSID
char* password="123456789"; //WiFi password
unsigned int localPort=2390; //local port to listen for UDP packets
IPAddress timeServerIP; //time.nist.gov NTP server address
const char* ntpServerName="time.nist.gov"; //NTP Server host name
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
WiFiUDP udp; //UDP instance to let us send and receive packets over UDP
void setup() {
Serial.begin(9600);
Serial.println();
Serial.println();
//Connecting to a WiFi network
Serial.print("Connecting to ");
Serial.println(ssid);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.println("WiFi connected");
Serial.print("IP address: ");
Serial.println(WiFi.localIP());
//Start UDP
Serial.println("Starting UDP");
udp.begin(localPort);
Serial.print("Local port: ");
Serial.println(udp.localPort());
}
void loop() {
//get a random server from the pool (get an IP from Server Name)
WiFi.hostByName(ntpServerName, timeServerIP);
sendNTPpacket(timeServerIP); //send an NTP packet to a time server
delay(1000); // wait to see if a reply is available
int cb=udp.parsePacket(); //return bytes received
if (!cb) {Serial.println("no packet yet");}
else { //received a packet, read the data from the buffer
Serial.print("packet received, length=");
Serial.println(cb); //=48
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=Greenwich Meridian (GMT)
Serial.print((epoch % 86400L) / 3600); //print the hour (86400 secs/day)
Serial.print(':');
//In the first 10 minutes of each hour, we'll want a leading '0'
if ( ((epoch % 3600) / 60) < 10 ) {Serial.print('0');}
Serial.print((epoch % 3600) / 60); // print the minute (3600 secs/minute)
Serial.print(':');
// In the first 10 seconds of each minute, we'll want a leading '0'
if ( (epoch % 60) < 10 ) {Serial.print('0');}
Serial.println(epoch % 60); // print the second
}
delay(10000);
}
unsigned long sendNTPpacket(IPAddress& address) {
Serial.println("sending NTP packet...");
// set all bytes in the buffer to 0
memset(packetBuffer, 0, NTP_PACKET_SIZE); //clear the buffer
//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); //send UDP request to NTP server
udp.endPacket();
} |