【零知ESP8266教程】快速入门19 使用NTP服务器获取网络时间

/*

 * TimeNTP_ESP8266WiFi.ino

 * Example showing time sync to NTP time source

 *

 * This sketch uses the ESP8266WiFi library

 */

  

#include <TimeLib.h>

#include <ESP8266WiFi.h>

#include <WiFiUdp.h>

  

const char ssid[] = "xx";  //  your network SSID (name)

const char pass[] = "xx";       // your network password

  

// NTP Servers:

static const char ntpServerName[] = "cn.ntp.org.cn";

//static const char ntpServerName[] = "time.nist.gov";

//static const char ntpServerName[] = "time-a.timefreq.bldrdoc.gov";

//static const char ntpServerName[] = "time-b.timefreq.bldrdoc.gov";

//static const char ntpServerName[] = "time-c.timefreq.bldrdoc.gov";

  

const int timeZone = 8; //BeiJing in China

  

// const int timeZone = 1;     // Central European Time

//const int timeZone = -5;  // Eastern Standard Time (USA)

//const int timeZone = -4;  // Eastern Daylight Time (USA)

//const int timeZone = -8;  // Pacific Standard Time (USA)

//const int timeZone = -7;  // Pacific Daylight Time (USA)

  

  

WiFiUDP Udp;

unsigned int localPort = 8888;  // local port to listen for UDP packets

  

time_t getNtpTime();

void digitalClockDisplay();

void printDigits(int digits);

void sendNTPpacket(IPAddress &address);

  

void setup()

{

  Serial.begin(9600);

  while (!Serial) ; // Needed for Leonardo only

  delay(250);

  Serial.println("TimeNTP Example");

  Serial.print("Connecting to ");

  Serial.println(ssid);

  WiFi.begin(ssid, pass);

  

  while (WiFi.status() != WL_CONNECTED) {

    delay(500);

    Serial.print(".");

  }

  

  Serial.print("IP number assigned by DHCP is ");

  Serial.println(WiFi.localIP());

  Serial.println("Starting UDP");

  Udp.begin(localPort);

  Serial.print("Local port: ");

  Serial.println(Udp.localPort());

  Serial.println("waiting for sync");

  setSyncProvider(getNtpTime);

  setSyncInterval(300);

}

  

time_t prevDisplay = 0; // when the digital clock was displayed

  

void loop()

{

  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

  Serial.print(hour());

  printDigits(minute());

  printDigits(second());

  Serial.print(" ");

  Serial.print(day());

  Serial.print(".");

  Serial.print(month());

  Serial.print(".");

  Serial.print(year());

  Serial.println();

}

  

void printDigits(int digits)

{

  // utility for digital clock display: prints preceding colon and leading 0

  Serial.print(":");

  if (digits < 10)

    Serial.print('0');

  Serial.print(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()

{

  IPAddress ntpServerIP; // NTP server's ip address

  

  while (Udp.parsePacket() > 0) ; // discard any previously received packets

  Serial.println("Transmit NTP Request");

  // get a random server from the pool

  WiFi.hostByName(ntpServerName, ntpServerIP);

  Serial.print(ntpServerName);

  Serial.print(": ");

  Serial.println(ntpServerIP);

  sendNTPpacket(ntpServerIP);

  uint32_t beginWait = millis();

  while (millis() - beginWait < 1500) {

    int size = Udp.parsePacket();

    if (size >= NTP_PACKET_SIZE) {

      Serial.println("Receive NTP Response");

      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("No NTP Response :-(");

  return 0; // return 0 if unable to get the time

}

  

// 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();

}