UDPSendReceiveString.ino

/*
 UDPSendReceiveString:
 This sketch receives UDP message strings, prints them to the serial port
 and sends an "acknowledge" string back to the sender

 A Processing sketch is included at the end of file that can be used to send
 and received messages for testing with a computer.

 created 21 Aug 2010
 by Michael Margolis

 This code is in the public domain.
 */


#include <NativeEthernet.h>
#include <NativeEthernetUdp.h>

// 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

// buffers for receiving and sending data
char packetBuffer[UDP_TX_PACKET_MAX_SIZE];  // buffer to hold incoming packet,
char ReplyBuffer[] = "acknowledged";        // a string to send back

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

void setup() {
  // You can use Ethernet.init(pin) to configure the CS pin
  //Ethernet.init(10);  // Most Arduino shields
  //Ethernet.init(5);   // MKR ETH shield
  //Ethernet.init(0);   // Teensy 2.0
  //Ethernet.init(20);  // Teensy++ 2.0
  //Ethernet.init(15);  // ESP8266 with Adafruit Featherwing Ethernet
  //Ethernet.init(33);  // ESP32 with Adafruit Featherwing Ethernet

  // start the Ethernet
  Ethernet.begin(mac, ip);

  // Open serial communications and wait for port to open:
  Serial.begin(9600);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }

  // Check for Ethernet hardware present
  if (Ethernet.hardwareStatus() == EthernetNoHardware) {
    Serial.println("Ethernet shield was not found.  Sorry, can't run without hardware. :(");
    while (true) {
      delay(1); // do nothing, no point running without Ethernet hardware
    }
  }
  if (Ethernet.linkStatus() == LinkOFF) {
    Serial.println("Ethernet cable is not connected.");
  }

  // start UDP
  Udp.begin(localPort);
}

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 a reply to the IP address and port that sent us the packet we received
    Udp.beginPacket(Udp.remoteIP(), Udp.remotePort());
    Udp.write(ReplyBuffer);
    Udp.endPacket();
  }
  delay(10);
}


/*
  Processing sketch to run with this example
 =====================================================

 // Processing UDP example to send and receive string data from Arduino
 // press any key to send the "Hello Arduino" message


 import hypermedia.net.*;

 UDP udp;  // define the UDP object


 void setup() {
 udp = new UDP( this, 6000 );  // create a new datagram connection on port 6000
 //udp.log( true ); 		// <-- printout the connection activity
 udp.listen( true );           // and wait for incoming message
 }

 void draw()
 {
 }

 void keyPressed() {
 String ip       = "192.168.1.177";	// the remote IP address
 int port        = 8888;		// the destination port

 udp.send("Hello World", ip, port );   // the message to send

 }

 void receive( byte[] data ) { 			// <-- default handler
 //void receive( byte[] data, String ip, int port ) {	// <-- extended handler

 for(int i=0; i < data.length; i++)
 print(char(data[i]));
 println();
 }
 */