【零知ESP8266教程】快速入门19 使用NTP服务器获取网络时间

上次的分享，我们获取了一枚天气信息，但是呢，信息最重要的属性之一就是时效性，如何去确认我们信息的时效性呢，简单，保持自己时间的准确喽。

Time is valuable thing！

时间对我们是很重要的。通常，我们需要进行时间校准（PS：在很多时候，你细心留意就发现时间是错误的），一般就可以用NTP服务器进行获取时间信息，下面使用零知-ESP8266上进行NTP时间的获取。

一、硬件
电脑，windows系统
零知ESP8266开发板
micro-usb线
二、
（1）打开零知开源开发软件，选择零知ESP8266开发板，界面如图所示：

（2）电脑连接零知ESP8266开发板

（3）烧写程序：
①可以直接选择软件中的示例程序

②也可以上传以下代码：

/*
 * TimeNTP_ESP8266WiFi.ino
 * Example showing time sync to NTP time source
 *
 * This sketch uses the ESP8266WiFi library
 */
  
#include 
#include 
#include 
  
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();
}

然后验证，并且上传到开发板。

四、结果

然后对照自己的时间：

赶紧动手检查看看自己的时间对不对呢？
我先校准自己的。

顺便问你们一句：有没有发现自己的时间变快了呢？（细思极恐）