NTPClient库 加注释
时间: 2023-06-29 20:14:00 浏览: 71
下面是一个带有注释的NTPClient库示例:
```c++
#include <Ethernet.h>
#include <EthernetUdp.h>
#include "NTPClient.h"
// Ethernet客户端对象
EthernetUDP udp;
// NTP服务器地址
IPAddress timeServerIP;
// NTP数据包缓冲
byte packetBuffer[NTP_PACKET_SIZE];
// NTP客户端对象
NTPClient::NTPClient(EthernetUDP udp) {
this->udp = udp;
}
// 同步时间
unsigned long NTPClient::syncTime() {
// 获取NTP服务器IP地址
EthernetDNS dns;
dns.begin(ethernet.dnsServerIP());
dns.getHostByName("pool.ntp.org", timeServerIP);
// 发送NTP数据包
memset(packetBuffer, 0, NTP_PACKET_SIZE);
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(timeServerIP, 123);
udp.write(packetBuffer, NTP_PACKET_SIZE);
udp.endPacket();
// 等待接收NTP响应
unsigned long startTime = millis();
while (udp.parsePacket() == 0) {
if (millis() - startTime > 1000) {
// 超时
return 0;
}
}
// 读取NTP响应
udp.read(packetBuffer, NTP_PACKET_SIZE);
// 解析NTP响应
unsigned long highWord = word(packetBuffer[40], packetBuffer[41]);
unsigned long lowWord = word(packetBuffer[42], packetBuffer[43]);
unsigned long secsSince1900 = highWord << 16 | lowWord;
const unsigned long seventyYears = 2208988800UL;
unsigned long epoch = secsSince1900 - seventyYears;
// 返回时间戳
return epoch;
}
```
注释解释了每个变量和函数的作用以及程序的工作原理。该程序使用Ethernet库和EthernetUdp库来与NTP服务器进行通信,并使用NTPClient类来同步时间。程序使用DNS解析获取NTP服务器的IP地址,然后发送NTP数据包并等待响应。一旦收到响应,程序将解析NTP数据包并计算出当前时间戳。
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