本文主要介绍如何在 Wio Terminal 上通过 NTP 同步网络时间。Wio Terminal 配备的无线 WiFi 网卡是 Realtek RTL8720，在开始本次学习之前，请确保你已经阅读 Wio Terminal 网卡固件更新，并完成固件更新和 Arduino 依赖库的安装。
本示例使用 UDP 获取 NTP 时间，并使用主控制器 SAMD51 内核上的内置 RTC 来保持时间更新。
安装依赖
为了完成本示例，需要安装两个依赖库 Seeed_Arduino_RTC 和 millisDelay。
1、在 Seeed_Arduino_RTC 的 GitHub 仓库 下载 zip 包。
2、在 millisDelay 的 GitHub 仓库 下载 zip 包。
3、在 Arduino IDE 中点击 项目 > 加载库 > 添加 .ZIP 库…，添加 Seeed_Arduino_RTC 和 millisDelay 库。
示例代码
#include <rpcWiFi.h>
#include <millisDelay.h>
#include "RTC_SAMD51.h"
const char ssid[] = "yourNetworkName"; // add your required ssid
const char password[] = "yourNetworkPassword"; // add your own netywork password
millisDelay updateDelay; // the update delay object. used for ntp periodic update.
unsigned int localPort = 2390; // local port to listen for UDP packets
char timeServer[] = "time.nist.gov"; // extenral NTP server e.g. time.nist.gov
const int NTP_PACKET_SIZE = 48; // NTP time stamp is in the first 48 bytes of the message
byte packetBuffer[NTP_PACKET_SIZE]; //buffer to hold incoming and outgoing packets
// declare a time object
DateTime now;
// define WiFI client
WiFiClient client;
//The udp library class
WiFiUDP udp;
// localtime
unsigned long devicetime;
RTC_SAMD51 rtc;
// for use by the Adafuit RTClib library
char daysOfTheWeek[7][12] = { "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday" };
void setup() {
Serial.begin(115200);
while (!Serial); // wait for serial port to connect. Needed for native USB
// setup network before rtc check
connectToWiFi(ssid, password);
// get the time via NTP (udp) call to time server
// getNTPtime returns epoch UTC time adjusted for timezone but not daylight savings
// time
devicetime = getNTPtime();
// check if rtc present
if (devicetime == 0) {
Serial.println("Failed to get time from network time server.");
}
if (!rtc.begin()) {
Serial.println("Couldn't find RTC");
while (1) delay(10); // stop operating
}
// get and print the current rtc time
now = rtc.now();
Serial.print("RTC time is: ");
Serial.println(now.timestamp(DateTime::TIMESTAMP_FULL));
// adjust time using ntp time
rtc.adjust(DateTime(devicetime));
// print boot update details
Serial.println("RTC (boot) time updated.");
// get and print the adjusted rtc time
now = rtc.now();
Serial.print("Adjusted RTC (boot) time is: ");
Serial.println(now.timestamp(DateTime::TIMESTAMP_FULL));
// start millisdelays timers as required, adjust to suit requirements
updateDelay.start(1 * 60 * 60 * 1000); // update time via ntp every hr
}
void loop() {
if (updateDelay.justFinished()) { // 12 hour loop
// repeat timer
updateDelay.repeat(); // repeat
// update rtc time
devicetime = getNTPtime();
if (devicetime == 0) {
Serial.println("Failed to get time from network time server.");
}
else {
rtc.adjust(DateTime(devicetime));
Serial.println("");
Serial.println("rtc time updated.");
// get and print the adjusted rtc time
now = rtc.now();
Serial.print("Adjusted RTC time is: ");
Serial.println(now.timestamp(DateTime::TIMESTAMP_FULL));
}
}
}
void connectToWiFi(const char* ssid, const char* pwd) {
Serial.println("Connecting to WiFi network: " + String(ssid));
// delete old config
WiFi.disconnect(true);
Serial.println("Waiting for WIFI connection...");
//Initiate connection
WiFi.begin(ssid, pwd);
while (WiFi.status() != WL_CONNECTED) {
WiFi.begin(ssid, pwd);
delay(500);
}
Serial.println("Connected.");
printWifiStatus();
}
unsigned long getNTPtime() {
// module returns a unsigned long time valus as secs since Jan 1, 1970
// unix time or 0 if a problem encounted
//only send data when connected
if (WiFi.status() == WL_CONNECTED) {
//initializes the UDP state
//This initializes the transfer buffer
udp.begin(WiFi.localIP(), localPort);
sendNTPpacket(timeServer); // send an NTP packet to a time server
// wait to see if a reply is available
delay(1000);
if (udp.parsePacket()) {
Serial.println("udp packet received");
Serial.println("");
// We've received a packet, read the data from it
udp.read(packetBuffer, NTP_PACKET_SIZE); // read the packet into the buffer
//the timestamp starts at byte 40 of the received packet and is four bytes,
// or two words, long. First, extract the two words:
unsigned long highWord = word(packetBuffer[40], packetBuffer[41]);
unsigned long lowWord = word(packetBuffer[42], packetBuffer[43]);
// combine the four bytes (two words) into a long integer
// this is NTP time (seconds since Jan 1 1900):
unsigned long secsSince1900 = highWord << 16 | lowWord;
// Unix time starts on Jan 1 1970. In seconds, that's 2208988800:
const unsigned long seventyYears = 2208988800UL;
// subtract seventy years:
unsigned long epoch = secsSince1900 - seventyYears;
// adjust time for timezone offset in secs +/- from UTC
// WA time offset from UTC is +8 hours (28,800 secs)
// + East of GMT
// - West of GMT
long tzOffset = 28800UL;
// WA local time
unsigned long adjustedTime;
return adjustedTime = epoch + tzOffset;
}
else {
// were not able to parse the udp packet successfully
// clear down the udp connection
udp.stop();
return 0; // zero indicates a failure
}
// not calling ntp time frequently, stop releases resources
udp.stop();
}
else {
// network not connected
return 0;
}
}
// send an NTP request to the time server at the given address
unsigned long sendNTPpacket(const char* address) {
// set all bytes in the buffer to 0
for (int i = 0; i < NTP_PACKET_SIZE; ++i) {
packetBuffer[i] = 0;
}
// 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();
}
void printWifiStatus() {
// print the SSID of the network you're attached to:
Serial.println("");
Serial.print("SSID: ");
Serial.println(WiFi.SSID());
// print your WiFi shield's IP address:
IPAddress ip = WiFi.localIP();
Serial.print("IP Address: ");
Serial.println(ip);
// print the received signal strength:
long rssi = WiFi.RSSI();
Serial.print("signal strength (RSSI):");
Serial.print(rssi);
Serial.println(" dBm");
Serial.println("");
}
运行效果
