ESP2866 Raspberry PI UDP Multicast Examples

ESPUDPReceiver.ino

#include <ESP8266WiFi.h>
#include <WiFiUdp.h>

const char* ssid     = "<YOURSSID>";
const char* password = "<YOURPASSWORD>";


void setup() 
{
  Serial.begin(115200);

  Serial.println();
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) 
  {
    delay(500);
    Serial.print(".");
  }

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

void loop()
{
  Serial.println("Setting Up To Receive");
  WiFiUDP udp;
  IPAddress address(239, 255, 255, 3);
  udp.beginMulticast(WiFi.localIP(), address, 2013);

  while (true)
  {
    int packetSize = udp.parsePacket();
    if (packetSize > 0)
    {
      char buffer[packetSize];
      udp.read(buffer, packetSize);
      buffer[packetSize - 1] = '\0';
      Serial.println(buffer);
    }
  }
}

ESPUDPSender.ino

#include <ESP8266WiFi.h>
#include <WiFiUdp.h>

const char* ssid     = "<YOURSSID>";
const char* password = "<YOURPASSWORD>";

void setup() 
{
  Serial.begin(115200);

  Serial.println();
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) 
  {
    delay(500);
    Serial.print(".");
  }

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

void loop()
{
  Serial.println("Sending packet");
  WiFiUDP udp;
  IPAddress address(239, 255, 255, 3);

  char send[] = "Hello Bob!";
  udp.beginPacketMulticast(address, 2013, WiFi.localIP());
  udp.write(send, strlen(send));
  udp.endPacket();

  delay(2000); //Don't flood remote service
}

QTUDPReceiver.pro

QT += core network
QT -= gui

CONFIG += c++11

TARGET = QTUDPReceiver
CONFIG += console
CONFIG -= app_bundle

TEMPLATE = app

SOURCES += rcvmain.cpp

# The following define makes your compiler emit warnings if you use
# any feature of Qt which as been marked deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

QTUDPSender.pro

QT += core network
QT -= gui

CONFIG += c++11

TARGET = QTUDPSender
CONFIG += console
CONFIG -= app_bundle

TEMPLATE = app

SOURCES += sndmain.cpp

# The following define makes your compiler emit warnings if you use
# any feature of Qt which as been marked deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

rcvmain.cpp

#include <QCoreApplication>
#include <QtNetwork>
#include <iostream>
#include <iomanip>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    QUdpSocket udpSocket4;
    QHostAddress groupAddress4(QStringLiteral("239.255.255.3"));

    if(false == udpSocket4.bind(QHostAddress::AnyIPv4, 2013, QUdpSocket::ShareAddress))
    {
        std::cout << "Socket Bind Failed" << std::endl;
        exit(12);
    }
    udpSocket4.joinMulticastGroup(groupAddress4);
    udpSocket4.setSocketOption(QAbstractSocket::MulticastTtlOption, 5);

    while(true)
    {
       QByteArray datagram;

       while(true == udpSocket4.hasPendingDatagrams())
       {
           datagram.resize(int(udpSocket4.pendingDatagramSize()));
           udpSocket4.readDatagram(datagram.data(), datagram.size());
           std::cout <<  datagram.constData()  << std::endl;
       }

    }

    return a.exec();
}

sndmain.cpp

#include <QCoreApplication>
#include <QtNetwork>
int main(int argc, char *argv[])
{
    int messageNo = 0;

    QCoreApplication a(argc, argv);
    QHostAddress groupAddress4(QStringLiteral("239.255.255.3"));
    QUdpSocket udpSocket4;
    udpSocket4.bind(QHostAddress(QStringLiteral("<YOURIPADDRESS>")), 0);
    udpSocket4.setSocketOption(QAbstractSocket::MulticastTtlOption, 5);

    while(true)
    {
        messageNo++;
        QByteArray datagram = "Multicast message " + QByteArray::number(messageNo);
        udpSocket4.writeDatagram(datagram, groupAddress4, 2013);

    }

    return a.exec();
}

Hello,

If you are here then you must be having troubles figuring put how to Get UDP multicast to work. i hope these examples save you time, as i wish I had them when I was implementing this on the ESP8266.