我正在尝试与使用WiFiShield发送UDP数据包的NTP服务器联系，以同步Arduino Uno上的时间。我已经花了几个小时阅读不同的教程和论坛，但没有成功。与我的代码无关，http://arduino.cc/en/Tutorial/UdpNTPClient的示例也不起作用。我没有回应。使用wireshark之后，我什至不确定Arduino是否甚至发送了数据包。
我试过的
为了让您放心，我将代码更改为不每10秒请求一次时间，但是它似乎始终都没有发送请求...
有小费吗？
来自http://arduino.cc/en/Tutorial/UdpNTPClient的代码:
/*
Udp NTP Client
Get the time from a Network Time Protocol (NTP) time server
Demonstrates use of UDP sendPacket and ReceivePacket
For more on NTP time servers and the messages needed to communicate with them,
see http://en.wikipedia.org/wiki/Network_Time_Protocol
created 4 Sep 2010
by Michael Margolis
modified 9 Apr 2012
by Tom Igoe
This code is in the public domain.
*/
#include <SPI.h>
#include <WiFi.h>
#include <WiFiUdp.h>
int status = WL_IDLE_STATUS;
char ssid[] = "mynetwork"; // your network SSID (name)
char pass[] = "mypassword"; // your network password
int keyIndex = 0; // your network key Index number (needed only for WEP)
unsigned int localPort = 2390; // local port to listen for UDP packets
IPAddress timeServer(129, 6, 15, 28); // time.nist.gov NTP server
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
// A UDP instance to let us send and receive packets over UDP
WiFiUDP Udp;
void setup()
{
// Open serial communications and wait for port to open:
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect. Needed for Leonardo only
}
// check for the presence of the shield:
if (WiFi.status() == WL_NO_SHIELD) {
Serial.println("WiFi shield not present");
// don't continue:
while(true);
}
// attempt to connect to Wifi network:
while ( status != WL_CONNECTED) {
Serial.print("Attempting to connect to SSID: ");
Serial.println(ssid);
// Connect to WPA/WPA2 network. Change this line if using open or WEP network:
status = WiFi.begin(ssid, pass);
// wait 10 seconds for connection:
delay(10000);
}
Serial.println("Connected to wifi");
printWifiStatus();
Serial.println("\nStarting connection to server...");
Udp.begin(localPort);
}
void loop()
{
sendNTPpacket(timeServer); // send an NTP packet to a time server
// wait to see if a reply is available
delay(1000);
Serial.println( Udp.parsePacket() );
if ( Udp.parsePacket() ) {
Serial.println("packet received");
// 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, esxtract 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;
Serial.print("Seconds since Jan 1 1900 = " );
Serial.println(secsSince1900);
// now convert NTP time into everyday time:
Serial.print("Unix time = ");
// 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;
// print Unix time:
Serial.println(epoch);
// print the hour, minute and second:
Serial.print("The UTC time is "); // UTC is the time at Greenwich Meridian (GMT)
Serial.print((epoch % 86400L) / 3600); // print the hour (86400 equals secs per day)
Serial.print(':');
if ( ((epoch % 3600) / 60) < 10 ) {
// In the first 10 minutes of each hour, we'll want a leading '0'
Serial.print('0');
}
Serial.print((epoch % 3600) / 60); // print the minute (3600 equals secs per minute)
Serial.print(':');
if ( (epoch % 60) < 10 ) {
// In the first 10 seconds of each minute, we'll want a leading '0'
Serial.print('0');
}
Serial.println(epoch %60); // print the second
}
// wait ten seconds before asking for the time again
delay(10000);
}
// send an NTP request to the time server at the given address
unsigned long sendNTPpacket(IPAddress& address)
{
//Serial.println("1");
// 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)
//Serial.println("2");
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;
//Serial.println("3");
// 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
//Serial.println("4");
Udp.write(packetBuffer,NTP_PACKET_SIZE);
//Serial.println("5");
Udp.endPacket();
//Serial.println("6");
}
void printWifiStatus() {
// print the SSID of the network you're attached to:
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");
}
最佳答案
尝试
memset(packetBuffer, 0, NTP_PACKET_SIZE);
packetBuffer[0] = 0b00011011; // (0x1B) for NTPv3
// or
// packetBuffer[0] = 0b00100011;` (0x23) for NTPv4
并且不要修改请求结构的其余部分。 NTP将使用此最小请求设置来响应客户端。
编辑:
localPort = 2390应该是“ntp-port”(123)吗？要么甚至是8888，如此处所述:“Network Time Protocol (NTP) Client”。 注意:链接
看起来与您的链接几乎相同，但并不相同。指定的端口不同。
代码是否超出了
setup()范围？...
// check for the presence of the shield:
if (WiFi.status() == WL_NO_SHIELD) {
Serial.println("WiFi shield not present");
// don't continue:
while(true);
}
...
对我来说看起来很奇怪。 “不要继续”被实施为忙于“待在这里”。
关于c++ - WiFiShield正在发送NTP请求数据包，但无响应，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/21049912/