前言：之前为了做我的网络时钟项目，便在网上寻找获取NTP网络时间的方法，看遍了网上的所有教程，无非就两种：

1.直接在主程序中获取时间戳，转换为当前时间，缺点就是 代码量太大。

2.使用NTPClient 库，相比于前一种方式，代码量确实下降了，但原谅我在其源码中并 没有找到获取年月日以及星期的函数，哈哈。如果重新写转换年月日的函数，那就没有Arduino的优势了（能用库绝对不自己写，嘿嘿~）

• 因此，今天我便要向大家介绍另一个方便的获取NTP时间的库：Time-master
• 库的安装请前往：https://github.com/PaulStoffregen/Time  或者  前往 Arduino 的库管理器安装
• 安装好库后，我们尝试写一个简单的例程：

/*
@作者：刘泽文
@功能：获取NTP时间，串口输出
 */

#include <TimeLib.h>
#include <ESP8266WiFi.h>
#include <WiFiUdp.h>

const char ssid[] = "********";  //你的WIFI
const char pass[] = "********";  //你的WIFI密码

// NTP Servers:
static const char ntpServerName[] = "time1.aliyun.com";//阿里云的时间服务器

const int timeZone = 8;     // 时区

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

time_t getNtpTime();
char *num_week(uint8_t dayofweek,int Mode);//计算星期
void digitalClockDisplay();
void printDigits(int digits);
void sendNTPpacket(IPAddress &address);

void setup()
{
  Serial.begin(9600);
  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();
    }
  }
}

/*
@功能:判断星期并赋值
*/
char week1[10],week2[8],week3[2],week4[4];
char *num_week(uint8_t dayofweek,int Mode){
  switch(dayofweek)
  {
    case 1: 
    strcpy(week1,"Sunday");
    strcpy(week2,"周日");
    strcpy(week3,"Su");
    strcpy(week4,"日"); 
      break;
    case 2: 
    strcpy(week1,"Monday");
    strcpy(week2,"周一");
    strcpy(week3,"Mo");
    strcpy(week4,"一"); 
      break;
    case 3: 
    strcpy(week1,"Tuesday");
    strcpy(week2,"周二");
    strcpy(week3,"Tu");
    strcpy(week4,"二"); 
      break;
    case 4: 
    strcpy(week1,"Wednesday");
    strcpy(week2,"周三"); 
    strcpy(week3,"We");
    strcpy(week4,"三"); 
      break;
    case 5: 
    strcpy(week1,"Thursday");
    strcpy(week2,"周四"); 
    strcpy(week3,"Th");
    strcpy(week4,"四"); 
      break;
    case 6: 
    strcpy(week1,"Friday");
    strcpy(week2,"周五");
    strcpy(week3,"Fr"); 
    strcpy(week4,"五");
      break;
    case 7: 
    strcpy(week1,"Saturday");
    strcpy(week2,"周六"); 
    strcpy(week3,"Sa");
    strcpy(week4,"六");
      break;
    default:
    strcpy(week1,"NO");
    strcpy(week2,"无");
    strcpy(week3,"NO");
    strcpy(week4,"无");
      break; 
  }
  switch(Mode)
  {
    case 1: return week1; break;
    case 2: return week2; break;
    case 3: return week3; break;
    case 4: return week4; break;
  }
}

void digitalClockDisplay()
{
  // digital clock display of the time
  Serial.print(year());
  Serial.print("/");
  Serial.print(month());
  Serial.print("/");
  Serial.print(day());
  Serial.print("   ");
  Serial.print(hour());
  printDigits(minute());
  printDigits(second());
  Serial.print("   星期");
  Serial.print(num_week(weekday(),4));
  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 (下面不用看哦)----------*/

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();
}

• 上传程序后打开串口监视器（波特率：9600） 看下效果：

我们可以看到时间与电脑时间分秒不差，哈哈，完美！！！