定义 UDP 数据包大小（Arduino）

Question

我写了一个草图来通过 UDP 发送传感器数据。我得到了每个包 1 个字节的简单传输。 我怎么define我的packagelenght，我需要buffer吗？

谢谢！

代码如下：

//Version 1.05

//necessary libraries
#include <SPI.h>
#include <Ethernet2.h>
#include <EthernetUdp2.h>

//Pin settings
#define CTD 19

//Network Settings
byte mac[] = { 0x90, 0xA2, 0xDA, 0x10, 0xEC, 0xAB };  //set MAC Address Ethernet Shield (Backside)
byte ip[]  = { XXX, XXX, X, X };                      //set IP-Address
byte gateway[] = { XXX, XXX, X, X };                  //set Gateway
byte subnet[]  = { 255, 255, 255, 0 };                //set Subnetmask


//local UDP port to listen on
unsigned int localPort = 5568;

//Recipient IP
IPAddress RecipientIP(XXX, XXX, X, X);

//Recipient UDP port
unsigned int RecipientPort = 8888;

//Buffer for sending data
char packetBuffer[UDP_TX_PACKET_MAX_SIZE];

//EthernetUDP instance
EthernetUDP Udp;

//CTD data
int incomingData = 0;


void setup()
{
   //Start Ethernet
  Ethernet.begin(mac, ip);

  //Start UDP
  Udp.begin(localPort);

  //for debug only
  Serial.begin(9600);

  //Serial baud rate for CTD
  Serial1.begin(1200);

  //Version 1.05
Serial.print("Version 1.05");

  //CTD
  pinMode(CTD, INPUT);
}

void loop()
{

//If CTD is sending
if (Serial1.available())
{
  //read incoming data
  incomingData = Serial1.read();

  //for debug only
  Serial.print("Data: ");
  Serial.println(incomingData, BIN);
}
//Send UDP packets

    //Debug only
    Serial.print("Packet");

    // send to the IP address and port
    Udp.beginPacket(RecipientIP, RecipientPort);
    Udp.write(incomingData);
    Udp.endPacket();
}

Answer 1

以下代码用于发送和接收数据包：

#include <SPI.h>         // needed for Arduino versions later than 0018
#include <Ethernet.h>
#include <EthernetUdp.h>         // UDP library from: bjoern@cs.stanford.edu 12/30/2008


// Enter a MAC address and IP address for your controller below.
// The IP address will be dependent on your local network:
byte mac[] = {  
  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
unsigned int localPort = 5683;      // local port to listen on

// buffers for receiving and sending data
char packetBuffer[UDP_TX_PACKET_MAX_SIZE]; //buffer to hold incoming packet,
char  ReplyBuffer[] = "Portland banjo shabby chic Vice dreamcatcher gluten-free. Fashion axe Godard bicycle rights before they sold out, try-hard selvage polaroid sriracha master cleanse biodiesel Schlitz Wes Anderson.";       // a string to send back

// An EthernetUDP instance to let us send and receive packets over UDP
EthernetUDP Udp;

void setup() {
  // start the Ethernet and UDP:
  Ethernet.begin(mac);
  Udp.begin(localPort);

  Serial.begin(115200);
}

void loop() {
  // if there's data available, read a packet
  int packetSize = Udp.parsePacket();
  if(packetSize)
  {
    Serial.print("Received packet of size ");
    Serial.println(packetSize);
    Serial.print("From ");
    IPAddress remote = Udp.remoteIP();
    for (int i =0; i < 4; i++)
    {
      Serial.print(remote[i], DEC);
      if (i < 3)
      {
        Serial.print(".");
      }
    }
    Serial.print(", port ");
    Serial.println(Udp.remotePort());

    // read the packet into packetBufffer
    Udp.read(packetBuffer,UDP_TX_PACKET_MAX_SIZE);
    Serial.println("Contents:");
    Serial.println(packetBuffer);
  }
  
  // Send
  Udp.beginPacket("192.168.3.147", 5683);
  Udp.write(ReplyBuffer);
  Udp.endPacket();
  
  delay(1000);
}

在下面的语句中获取大小：

int packetSize = Udp.parsePacket();