Arduino Function: EthernetUDP.read

Description

Reads UDP data from the specified buffer. If no arguments are given, it will return the next character in the buffer. NOTE: this function can only be successfully called after UDP.parsePacket().

Syntax

UDP.read();
UDP.read(packetBuffer, MaxSize);

Parameters

packetBuffer: buffer to hold incoming packets (char) *MaxSize: maximum size of the buffer (int)

Returns

 It returns the characters in the buffer. *char

Examples

#include         
#include  //If you are using Ethernet Shield 2, use instead 
#include 

// 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 };
IPAddress ip(192, 168, 1, 177);

unsigned int localPort = 8888;      // local port to listen on

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

char packetBuffer[UDP_TX_PACKET_MAX_SIZE]; //buffer to hold incoming packet,

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

void loop() {
  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);
  }
}


Based on the reference originally written by Arduino Community,  wiring.org.co and  arduino.cc