here is a UDP chat program for a Mega with a ethernet shield
// UDP chat program using Arduino Ethernet Shield
#include <SPI.h>
#include <Ethernet.h>
#include <EthernetUdp.h>
#define UDP_TX_PACKET_MAX_SIZE 100 //increase UDP size
byte mac[] = {0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED}; // MAC address update as required
IPAddress localIP(192, 168, 1, 176); // local static localIP address
IPAddress remoteIP(192, 168, 1, 68); // local static localIP address
unsigned int port = 999; // port to receive/transmit
char packetBuffer[UDP_TX_PACKET_MAX_SIZE]; //buffer to hold incoming packet
EthernetUDP Udp; // An EthernetUDP instance to let us send and receive packets over UDP
void setup() {
Serial.begin(115200);
Serial.println("\n\nUDP chat program");
// select static or dynamic IP initialization
//Ethernet.begin(mac, localIP); // static IP initialize Ethernet shield
if(Ethernet.begin(mac)) // dyname IP initialize Ethernet shield using DHCP
Serial.println("Configured Ethernet using DHCP OK");
else Serial.println("Failed to configure Ethernet using DHCP");
Serial.print("My localIP address: "); // print local localIP address:
Serial.println(Ethernet.localIP());
// Initializes the ethernet UDP library and network settings.
if (Udp.begin(port)) Serial.println("UDP begin() OK");
else Serial.println("UDP begin() failed!");
Serial.print("UDP_TX_PACKET_MAX_SIZE ");
Serial.println(UDP_TX_PACKET_MAX_SIZE);
}
void loop() {
// if datagram received read it
int packetSize = Udp.parsePacket();
if (packetSize) {
Serial.print("Received packet of size ");
Serial.print(packetSize); // datagram packet size
Serial.print(" From ");
remoteIP = Udp.remoteIP(); // from localIP
Serial.print(remoteIP);
Serial.print(", port "); // from port
Serial.println(Udp.remotePort());
memset(packetBuffer, 0, UDP_TX_PACKET_MAX_SIZE);
// read the packet into packetBufffer and print contents
Udp.read(packetBuffer, UDP_TX_PACKET_MAX_SIZE);
Serial.print("Contents: ");
Serial.println(packetBuffer);
}
if (Serial.available()) { // if text entered read it and send it
char text[100] = { 0 };
Serial.readBytesUntil('\n', text, 100);
Serial.print("Transmitting datagram ");
Serial.println(text);
Udp.beginPacket(remoteIP, port); // send to remote localIP and port 999
Udp.write(text);
Udp.endPacket();
}
delay(10);
}
java programs for PC in file UDPchat.java
// UDPchat.java - simple peer-to-peer chat program using UDP
// - given remote IP address can send strings using UDP datagrams
// - will also wait for datagrams and display contents
// remote IP and port are specified via command line - default IP is 127.0.0.1 (i.e. localhost) and port is 1000
//
// e.g. to send datagrams to IP 146.227.59.130 port 1006
// java chat 146.227.59.130 1006
import java.io.*;
import java.util.*;
import java.net.*;
public class UDPchat extends Thread
{
private final static BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
int port=999;//10001;// 10000; // port to send/receive datagrams on
String remoteIPaddress= "192.168.1.177";//"169.254.144.20";//("192.168.1.8");//127.0.0.1"); // IP to send datagrams
// constructor, parameter is command line parameters
public UDPchat(String args[]) throws Exception
{
// get remote IP address and port from command line parameters
if (args.length > 0) remoteIPaddress = (args[0]); // get IPaddress
if (args.length > 1) port = Integer.parseInt(args[1]); // get port number
System.out.println("chat program: IP address " + InetAddress.getLocalHost().toString() + " port " + port );
start(); // start thread to receive and display datagrams
// loop waiting for keyboard input, send datagram to remote IP
while(true)
try
{
String s = in.readLine(); // read a String
System.out.println("Sending to " + remoteIPaddress + " socket " + port + " data: " + s);
byte[] data = s.getBytes(); // convert to byte array
DatagramSocket theSocket = new DatagramSocket(); // create datagram socket and the datagram
DatagramPacket theOutput = new DatagramPacket(data, s.length(), InetAddress.getByName(remoteIPaddress), port);
theSocket.send(theOutput); // and send the datagram
}
catch (Exception e) {System.out.println("Eroor sending datagram " + e);}
}
// thread run method, receives datagram and display contents as a string
public void run()
{
try
{
// open DatagramSocket to receive
DatagramSocket ds = new DatagramSocket(port);
// loop forever reading datagrams from the DatagramSocket
while (true)
{
byte[] buffer = new byte[65507]; // array to put datagrams in
DatagramPacket dp = new DatagramPacket(buffer, buffer.length); // DatagramPacket to hold the datagram
ds.receive(dp); // wait for next datagram
String s = new String(dp.getData(),0,dp.getLength()); // get contenets as a String
System.out.println("UDP datagram length " + s.length()+ " from IP " + dp.getAddress() + " received: " + s );
s = "Acknowledge\n";
// byte[] data = s.getBytes(); // convert to byte array
// DatagramSocket theSocket = new DatagramSocket(); // create datagram socket and the datagram
// DatagramPacket theOutput = new DatagramPacket(data, data.length, InetAddress.getByName(remoteIPaddress), port);
// theSocket.send(theOutput); // and send the datagram
}
}
catch (SocketException se) {System.err.println("chat error " + se); }
catch (IOException se) {System.err.println("chat error " + se);}
System.exit(1); // exit on error
}
public static void main(String args[]) throws Exception
{
UDPchat c=new UDPchat(args);
}
}
test run serial output from Mega
UDP chat program
Configured Ethernet using DHCP OK
My localIP address: 192.168.1.177
UDP begin() OK
UDP_TX_PACKET_MAX_SIZE 100
Received packet of size 5 From 192.168.1.65, port 53704
Contents: hello
Transmitting datagram hello from mega
Received packet of size 21 From 192.168.1.65, port 51635
Contents: hello from java on PC
Transmitting datagram test 2 from mega
Received packet of size 14 From 192.168.1.65, port 53386
Contents: test 2 from PC
output on PC
F:\Ardunio\Networking\Ethernet\UDP\UDP_chat>java UDPchat
chat program: IP address BB-DELL2/172.26.208.1 port 999
hello
Sending to 192.168.1.177 socket 999 data: hello
UDP datagram length 16 from IP /192.168.1.177 received: hello from mega
hello from java on PC
Sending to 192.168.1.177 socket 999 data: hello from java on PC
UDP datagram length 17 from IP /192.168.1.177 received: test 2 from mega
test 2 from PC
Sending to 192.168.1.177 socket 999 data: test 2 from PC
I think I have a Python UDPchat program some where - will try to find it
