In this example is shown how to realize a simple Chat Server, using the WiFi Link library on the Arduino STAR OTTO.
This Chat uses a Telnet protocol to exchange the messages. If you are a Windows user then you could use Putty.

Use the Arduino IDE 1.8.x  and import the WiFi Link library using the Library Manager.

WiFi Link library



Connect the board to PC

 Arduino STAR OTTO


Now, modify the below sketch inserting the name and the password of your network and after upload the code using Arduino IDE.
This example is written for a WPA encryption network. If you want to use it  for WEP or WPA, change the Wifi.begin() call accordingly.


If you use the IDE sketch then replace the Serial with SerialUSB.


Use the Arduino IDE 1.8.x and check that you have already downloaded the corresponding platform (Arduino STM32F4 Boards) from the Board Manager

Chat Server

A simple server that distributes any incoming messages to all
connected clients. To use telnet to your device's IP address and type.
You can see the client's input in the serial monitor as well.

This example is written for a network using WPA encryption. For
WEP or WPA, change the Wifi.begin() call accordingly.

* Arduino Primo or STAR OTTO or Uno WiFi Developer Edition (with WiFi Link firmware running)

created 18 Dec 2009
by David A. Mellis
modified 31 May 2012
by Tom Igoe
modified 10 March 2017
by Sergio Tomasello and Andrea Cannistrá

#include <WiFiLink.h>
#define Serial SerialUSB

char ssid[] = "yourNetwork"; // your network SSID (name)
char pass[] = "secretPassword"; // your network password (use for WPA, or use as key for WEP)

int keyIndex = 0; // your network key Index number (needed only for WEP)

int status = WL_IDLE_STATUS;

WiFiServer server(23);

boolean alreadyConnected = false; // whether or not the client was connected previously

void setup() {
//Initialize serial and wait for port to open:
while (!Serial) {
; // wait for serial port to connect. Needed for native USB port only

//Check if communication with wifi module has been established
if (WiFi.status() == WL_NO_WIFI_MODULE_COMM) {
Serial.println("Communication with WiFi module not established.");
while (true); // don't continue:

// attempt to connect to Wifi network:
while ( status != WL_CONNECTED) {
Serial.print("Attempting to connect to SSID: ");
// Connect to WPA/WPA2 network. Change this line if using open or WEP network:
status = WiFi.begin(ssid, pass);

// wait 10 seconds for connection:

// start the server:
// you're connected now, so print out the status:

void loop() {
// wait for a new client:
WiFiClient client = server.available();

// when the client sends the first byte, say hello:
if (client) {
if (!alreadyConnected) {
// clead out the input buffer:
Serial.println("We have a new client");
client.println("Hello, client!");
alreadyConnected = true;

if (client.available() > 0) {
// read the bytes incoming from the client:
char thisChar = client.read();
// echo the bytes back to the client:
// echo the bytes to the server as well:

void printWifiStatus() {
// print the SSID of the network you're attached to:
Serial.print("SSID: ");

// print your WiFi shield's IP address:
IPAddress ip = WiFi.localIP();
Serial.print("IP Address: ");

// print the received signal strength:
long rssi = WiFi.RSSI();
Serial.print("signal strength (RSSI):");
Serial.println(" dBm");


Open the Serial Monitor, check the ip address and use it to open a Telenet chat:

Open Telnet

Type the correct ip address and enter in the chat:

Opening chat

Now, write on the chat and good fun: