esp8266获取网络时间

要获取网络时间，你需要连接到互联网并与一个时间服务器进行通信。ESP8266可以通过NTP协议与时间服务器进行通信，以获取当前日期和时间。

以下是ESP8266使用NTP协议获取网络时间的示例代码：

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

WiFiUDP udp;
unsigned int localPort = 8888;  //本地端口

void setup() {
  Serial.begin(115200);
  WiFi.mode(WIFI_STA);
  WiFi.begin("your_SSID", "your_PASSWORD");

  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi...");
  }
  Serial.println("Connected to WiFi");

  udp.begin(localPort);
}

void loop() {
  //向NTP服务器发送请求
  IPAddress timeServerIP;
  WiFi.hostByName("cn.pool.ntp.org", timeServerIP); //设置NTP服务器地址
  Serial.println(timeServerIP);
  sendNTPpacket(timeServerIP);

  //等待NTP服务器响应
  delay(1000);
  if (udp.parsePacket()) {
    Serial.println("Receive NTP Response");
    byte packetBuffer[48];
    udp.read(packetBuffer, 48); //读取NTP响应数据包
    unsigned long secsSince1900;
    //将时间戳转换为秒数
    secsSince1900 = (unsigned long)packetBuffer[40] << 24;
    secsSince1900 |= (unsigned long)packetBuffer[41] << 16;
    secsSince1900 |= (unsigned long)packetBuffer[42] << 8;
    secsSince1900 |= (unsigned long)packetBuffer[43];
    //计算当前时间
    unsigned long epoch = secsSince1900 - 2208988800UL;
    Serial.println(epoch);
    struct tm *ptm = gmtime((time_t *)&epoch);
    Serial.print(ptm->tm_year + 1900);
    Serial.print("-");
    Serial.print(ptm->tm_mon + 1);
    Serial.print("-");
    Serial.print(ptm->tm_mday);
    Serial.print(" ");
    Serial.print(ptm->tm_hour + 8);
    Serial.print(":");
    Serial.print(ptm->tm_min);
    Serial.print(":");
    Serial.println(ptm->tm_sec);
  }
}

//发送NTP请求数据包
void sendNTPpacket(IPAddress &address) {
  byte packetBuffer[48];
  memset(packetBuffer, 0, 48);
  packetBuffer[0] = 0b11100011;
  packetBuffer[1] = 0;
  packetBuffer[2] = 6;
  packetBuffer[3] = 0xEC;
  packetBuffer[12] = 49;
  packetBuffer[13] = 0x4E;
  packetBuffer[14] = 49;
  packetBuffer[15] = 52;

  udp.beginPacket(address, 123);
  udp.write(packetBuffer, 48);
  udp.endPacket();
}

在上面的示例代码中，我们使用了一个NTP服务器地址`cn.pool.ntp.org`，你可以根据自己的位置和需求更改它。在`loop()`函数中，我们首先发送一个NTP请求数据包到NTP服务器，然后等待NTP响应数据包。如果收到NTP响应数据包，则从数据包中读取时间戳，并将其转换为当前时间，最后将当前时间打印到串口上。