以太网屏蔽+ arduino的问题

Question

我目前正在尝试一些关于以太网屏蔽的 Arduino 示例中的简单（就绪）程序。我仍然没有结果。我总是收到我没有连接或空白的串行监视器。有谁知道为什么？我认为我已连接到 DHCP，因为我在路由器的 DHCP 列表中

<#include <SPI.h>
#include <Ethernet.h>
#include <EthernetUdp.h>

 // Enter a MAC address for your controller below.
 // Newer Ethernet shields have a MAC address printed on a sticker on the shield
byte mac[] = {
  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED
 };

unsigned int localPort = 8888;      // local port to listen for UDP packets

IPAddress timeServer(192, 43, 244, 18); // 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
EthernetUDP 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
 }


  // start Ethernet and UDP
  if (Ethernet.begin(mac) == 0) {
  Serial.println("Failed to configure Ethernet using DHCP");
 // no point in carrying on, so do nothing forevermore:
  for (;;)
   ;
 }
  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);
  if ( Udp.parsePacket() ) {
// 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)
{
// 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)
  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();
}

Answer 1

如果您的以太网屏蔽是廉价的克隆，那么它们就会出现故障。 您可以通过将其直接插入 DHCP 服务器来获取 DHCP 地址，但如果将屏蔽连接到交换机，您将无法获取地址。

您可以通过将 2 x 100 欧姆电阻器焊接到屏蔽底部网络插座的正确引脚来解决此问题。

或者，使用静态 IP 地址，或购买不同的以太网屏蔽。