155 lines
5.2 KiB
C++
155 lines
5.2 KiB
C++
/*
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WiFiEsp example: UdpNTPClient
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Get the time from a Network Time Protocol (NTP) time server.
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Demonstrates use of UDP to send and receive data packets
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For more on NTP time servers and the messages needed to communicate with them,
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see http://en.wikipedia.org/wiki/Network_Time_Protocol
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NOTE: The serial buffer size must be larger than 36 + packet size
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In this example we use an UDP packet of 48 bytes so the buffer must be
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at least 36+48=84 bytes that exceeds the default buffer size (64).
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You must modify the serial buffer size to 128
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For HardwareSerial modify _SS_MAX_RX_BUFF in
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Arduino\hardware\arduino\avr\cores\arduino\SoftwareSerial.h
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For SoftwareSerial modify _SS_MAX_RX_BUFF in
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Arduino\hardware\arduino\avr\libraries\SoftwareSerial\SoftwareSerial.h
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*/
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#include "WiFiEsp.h"
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#include "WiFiEspUdp.h"
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// Emulate Serial1 on pins 6/7 if not present
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#ifndef HAVE_HWSERIAL1
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#include "SoftwareSerial.h"
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SoftwareSerial Serial1(6, 7); // RX, TX
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#endif
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char ssid[] = "Twim"; // your network SSID (name)
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char pass[] = "12345678"; // your network password
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int status = WL_IDLE_STATUS; // the Wifi radio's status
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char timeServer[] = "time.nist.gov"; // NTP server
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unsigned int localPort = 2390; // local port to listen for UDP packets
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const int NTP_PACKET_SIZE = 48; // NTP timestamp is in the first 48 bytes of the message
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const int UDP_TIMEOUT = 2000; // timeout in miliseconds to wait for an UDP packet to arrive
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byte packetBuffer[NTP_PACKET_SIZE]; // buffer to hold incoming and outgoing packets
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// A UDP instance to let us send and receive packets over UDP
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WiFiEspUDP Udp;
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void setup()
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{
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// initialize serial for debugging
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Serial.begin(115200);
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// initialize serial for ESP module
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Serial1.begin(9600);
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// initialize ESP module
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WiFi.init(&Serial1);
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// check for the presence of the shield
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if (WiFi.status() == WL_NO_SHIELD) {
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Serial.println("WiFi shield not present");
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// don't continue
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while (true);
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}
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// attempt to connect to WiFi network
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while ( status != WL_CONNECTED) {
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Serial.print("Attempting to connect to WPA SSID: ");
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Serial.println(ssid);
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// Connect to WPA/WPA2 network
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status = WiFi.begin(ssid, pass);
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}
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// you're connected now, so print out the data
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Serial.println("You're connected to the network");
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Udp.begin(localPort);
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}
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void loop()
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{
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sendNTPpacket(timeServer); // send an NTP packet to a time server
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// wait for a reply for UDP_TIMEOUT miliseconds
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unsigned long startMs = millis();
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while (!Udp.available() && (millis() - startMs) < UDP_TIMEOUT) {}
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Serial.println(Udp.parsePacket());
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if (Udp.parsePacket()) {
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Serial.println("packet received");
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// We've received a packet, read the data from it into the buffer
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Udp.read(packetBuffer, NTP_PACKET_SIZE);
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// the timestamp starts at byte 40 of the received packet and is four bytes,
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// or two words, long. First, esxtract the two words:
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unsigned long highWord = word(packetBuffer[40], packetBuffer[41]);
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unsigned long lowWord = word(packetBuffer[42], packetBuffer[43]);
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// combine the four bytes (two words) into a long integer
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// this is NTP time (seconds since Jan 1 1900):
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unsigned long secsSince1900 = highWord << 16 | lowWord;
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Serial.print("Seconds since Jan 1 1900 = ");
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Serial.println(secsSince1900);
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// now convert NTP time into everyday time:
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Serial.print("Unix time = ");
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// Unix time starts on Jan 1 1970. In seconds, that's 2208988800:
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const unsigned long seventyYears = 2208988800UL;
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// subtract seventy years:
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unsigned long epoch = secsSince1900 - seventyYears;
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// print Unix time:
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Serial.println(epoch);
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// print the hour, minute and second:
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Serial.print("The UTC time is "); // UTC is the time at Greenwich Meridian (GMT)
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Serial.print((epoch % 86400L) / 3600); // print the hour (86400 equals secs per day)
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Serial.print(':');
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if (((epoch % 3600) / 60) < 10) {
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// In the first 10 minutes of each hour, we'll want a leading '0'
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Serial.print('0');
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}
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Serial.print((epoch % 3600) / 60); // print the minute (3600 equals secs per minute)
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Serial.print(':');
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if ((epoch % 60) < 10) {
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// In the first 10 seconds of each minute, we'll want a leading '0'
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Serial.print('0');
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}
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Serial.println(epoch % 60); // print the second
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}
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// wait ten seconds before asking for the time again
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delay(10000);
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}
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// send an NTP request to the time server at the given address
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void sendNTPpacket(char *ntpSrv)
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{
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// set all bytes in the buffer to 0
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memset(packetBuffer, 0, NTP_PACKET_SIZE);
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// Initialize values needed to form NTP request
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// (see URL above for details on the packets)
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packetBuffer[0] = 0b11100011; // LI, Version, Mode
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packetBuffer[1] = 0; // Stratum, or type of clock
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packetBuffer[2] = 6; // Polling Interval
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packetBuffer[3] = 0xEC; // Peer Clock Precision
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// 8 bytes of zero for Root Delay & Root Dispersion
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packetBuffer[12] = 49;
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packetBuffer[13] = 0x4E;
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packetBuffer[14] = 49;
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packetBuffer[15] = 52;
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// all NTP fields have been given values, now
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// you can send a packet requesting a timestamp:
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Udp.beginPacket(ntpSrv, 123); //NTP requests are to port 123
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Udp.write(packetBuffer, NTP_PACKET_SIZE);
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Udp.endPacket();
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}
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